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					                                                     Graedons’ Guide to

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                                                                       Thyroid Hormones
        T
Symptoms of
Low Thyroid
                                      T           he thyroid gland has surprising
                                                  power for such an unobtrusive or-
                                                  gan. It controls how fast every cell
                                                                                                               body such as the legs, underarms and
                                                                                                               pubic region in addition to the scalp.
                                                                                                                 The doctor will also check for a slow
Activity                                          in the body uses energy. It also                             Achilles reflex, look for a swollen area
                                           affects cells’ response to growth hormone                           around the eyes, and ask about a
    Apathy                                 and other compounds, including estrogen                             woman’s menstrual cycle. Heavy bleed-
    Fatigue                                and calcium. Because of its widespread                              ing may be associated with inadequate
    Dry skin                               impact, though, symptoms of thyroid prob-                           thyroid hormone, and women without
    Weakness                               lems may be vague and general, making                               enough thyroid may have trouble get-
    Constipation
                                           diagnosis difficult.                                                ting pregnant. Depression and difficulty
    Hair loss
    Cold intolerance
                                                                                                               concentrating are sometimes the main
    Puffy eyes
                                           Underactive Thyroid                                                 symptoms. For a diagnosis, the physi-
    Decreased sweating                       If the gland is producing too little thy-                         cian will need to check thyroid hormone
    Infertility                            roid hormone (thyroxine), a person may                              levels with a blood test.
    Heavy menstruation                                                                                            To treat hypothyroidism (too little
                                           become easily chilled, sometimes running
    Lower libido
                                           lower-than-normal temperatures on a                                  thyroid activity), doctors prescribe syn-
    Swollen hands or
          legs                             thermometer. Fatigue and constipation                                thetic hormone in pills such as
    Brittle fingernails                    are common complaints in this condition.                             Synthroid, Levoxyl or Levothroid
    Slow pulse                             Weight gain may result from inadequate                               to supplement or replace the patient's
    Anemia                                 thyroxine, particularly due to increased                             inadequate supply. They used to be-
    Elevated cholesterol                   fluid retention. Thyroid deficiency can                              lieve there were no side effects to thy-
    Shortness of breath                    sap muscle strength and lead to shortness                            roid therapy if the dose was appropri-
          during exercise                  of breath during exertion.                                           ate. But now scientists suspect that
    Hoarse voice                                                                                                thyroxine may increase the risk of os-
                                             Thick, dry skin, brittle fingernails and
    Clumsiness                             s
                                           coarse sparse hair are not unusual. When                             teoporosis, especially at higher than
    Depression
    Mental slowness                        the outer third of the eyebrows is missing,                          normal doses. This could be especially
    Carpal tunnel                          it strongly suggests low thyroid function.                           serious for older women, who are at
          syndrome                         Hair may also fall out on other parts of the                         the greatest risk of bone loss.


                                     CAN THYROID HORMONE WEAKEN BONES?
  Thyroid hormone has a profound effect on bone metabolism. People whose thyroid glands are overactive
(hyperthyroidism) are at high risk of osteoporosis. Doctors have learned that when they give too much thyroid
hormone to treat underactive glands, their patients also end up with weakened bones.
  Preliminary research has suggested that even normal doses of thyroid replacement hormone may lead to
reduced bone density. This finding is unexpected and disquieting, but another report indicates that if thyroid
therapy results in TSH values within the normal range, bone loss is minimized. Most recently, a study of older
women found that long-term treatment with 200 micrograms or more of thyroid hormone was associated with
lower bone mineral density. Postmenopausal estrogen therapy offset this bone loss.
  Under these circumstances, it makes sense to take care with the dose of thyroid hormone. This requires
close communication and periodic testing. Age and other medications may affect the body's requirements for
thyroid hormone. Bone density measurements may be called for, and if signs of osteoporosis begin to appear,
preventive treatment may become prudent.
   References: Kung, A.W.C., & Pun, K. K. Bone Mineral Density in Premenopausal Women Receiving Long-term Physiological Doses of Levothyroxine. JAMA
1991;265:2688-2691. Greenspan, S. L., et al. Skeletal integrity in premenopausal and postmenopausal women receiving long-term l-thyroxine therapy. Am. J. Med. 1991;
91:5-14. Schneider, D.L. et al. Thyroid Hormone Use and Bone Mineral Density in Elderly Women: Effects of Estrogen. JAMA 1994; 271:1245-1249.

© 2003 Graedon Enterprises, Inc.
                        SOME MEDICINES THAT AFFECT THYROID TESTS


Drug                     Test                               Effect

Amiodarone                Total T4, serum T3, reverse T3   Raises T4, lowers T3 levels and increases rT3
 Cordarone                TSH                              and TSH. Abnormal tests may persist weeks
                                                           or months after drug is discontinued. Drug
                                                           may trigger thyroid function problems in some
                                                           patients.
Anabolic steroids         Total T4, serum T3, TSH          Lowers test values; levothyroxine dose may
 Testosterone, etc.                                        need reduction
Aspirin (large doses)     Total T4                         Lowers reading without affecting thyroid
                                                           function
Carbamazepine             Total T4, T3 resin uptake,       Lowers test values. In combination with other
 Tegretol                 others                           anticonvulsants, may affect thyroid
Corticosteroids           Total T4, serum T3, TSH          Lowers test values
 Celestone
 Cortef
  Cortisone, etc.
Estrogen                  Total T4                         Raises reading without necessarily affecting
 Estrace                                                   thyroid function
 Estraderm
 Premarin, etc.
Haloperidol               TSH                              TSH scores tend to increase
Heparin                   TSH                              TSH values may be low
Iodine-containing         All                              Thyroid function tests may be altered up to a
  contrast media                                           few years after the x-ray or myelogram.
Lithium                   All                              Readings may be altered indicating reduced
 Eskalith                                                  thyroid function. In some cases, thyroid
 Lithane                                                   function is suppressed.
 Lithobid, etc.
Metoclopramide            TSH                              TSH tends to be higher
 Reglan
Oral Contraceptives       Total T4                         Raises reading without necessarily affecting
 Demulen 1/50                                              thyroid function
 Norlestrin
 Ovral, etc.
Parkinson's disease       TSH                              Test value lowered
drugs
 Parlodel
 Sinemet
 Symmetrel
Phenytoin (high dose)     Total T4                         Lowers reading without affecting thyroid
 Dilantin                                                  function
Perphenazine              Total T4                         Raises reading without affecting thyroid
 Trilafon (long-term)                                      function
Propranolol (large        T3, serum T4                     Serum T3 decreases, serum T4 may increase
  doses >160 mg)                                           without change in thyroid function
Salsalate                 Total T4, serum T3, etc.         Test readings are significantly lower; thyroid
  Disalcid                                                 function is not altered
Tamoxifen                 Total T4                         Raises reading without affecting thyroid
 Nolvadex                                                  function




2
               NORMAL VALUES OF THYROID BLOOD                                                Normal values may
                           TESTS                                                             vary from lab to lab.

    Serum TSH by immunoradiometric assay (IRMA)                 0.4-5 mcU/ml

    Total Serum T4                                              5-12 mcg/dL

    Serum T3                                                    80-180 ng/dL

    T3 Resin Uptake                                             25-35 percent
                                                                                           Conditions that
    Thyroxine-binding globulin capacity                         15-25 mcg T4/dL            May Require
                                                                                           Change in Dose
                                                                                            Aging
                                                                                            Malabsorption
Thyroid Testing                              that the thyroid gland is underactive, the     Pregnancy
                                             doctor may order a TRH. This test utilizing    Thyroid surgery
   Because the symptoms are non-specific,    thyrotropin-releasing hormone is a way         Treatment with
diagnosis of thyroid disorders requires a    of stimulating the pituitary gland to            other drugs:
careful history and sophisticated blood      determine how it responds; a large                Carafate
test. The best test is one called an         response to TRH suggests an underactive           Cordarone
immunoradiometric assay (IRMA). It           thyroid gland.                                    Dilantin
measures the level of a brain hormone           Many drugs can affect thyroid function         Estrogen**
called “thyroid stimulating hormone,” or     tests. Make sure your doctor is aware of          Iron
TSH for short. Sometimes it may be           all the medicines you are taking. This is         Questran
termed “thyrotropin.”                        especially important in the case of the           Rifampin
   TSH controls the action of the thyroid    radioimmunoassay (RIA) for serum total            Tegretol
gland the way a thermostat controls the      T4 and the test for T3 resin uptake.
                                                                                                     *
                                                                                               Testosterone
activity of a furnace: when the gland is     Although these older blood tests may still
making too little thyroid hormone, the       be done as part of a thyroid panel,
brain puts out more TSH to tell it to make   medications such as estrogen or Dilantin
more. If there is too much thyroid hormone   may alter their values and give misleading
in the bloodstream, the brain's output of    results. See the table on page 2.
TSH will drop, sometimes almost to
nothing. As a result, the TSH level is a
very good, upside-down indicator of          Pregnancy
thyroid function: when you have too little
thyroid hormone, TSH is high; if you have       Just as estrogens in birth control pills   * Wardle, Fraser &
too much, TSH will be very low. A third-     or postmenopausal hormone regimens            Squire. “Pitfalls in the use
generation sensitive TSH is most accurate.   alter thyroid function tests, so does         of thyrotropin concentra-
Some experts recommend, however, that        pregnancy. This can make an accurate          tion as a first-line thyroid-
total thyroxine be considered as well, to                                                  function test.” The Lancet
                                             assessment of thyroid function more
                                                                                           2001; 357:1013-1014.
detect pituitary abnormalities.*             difficult. Determination of free T4 may
   Should you be treated if your doctor      also be needed to correct for the increase
discovers an abnormal TSH level but you      in blood protein that binds to thyroxine.
have no other symptoms? This is              TSH should not be affected in women
controversial. People with subclinical       with normal thyroid function, but many
hypothyroidism           may       become    who were being treated for thyroid            **Arafah. “Increased
symptomatic, but they may also do well       problems before conceiving may need           need for thyroxine in
for years without treatment. Some experts    higher doses of thyroxine during              women with hypothy-
believe treatment to normalize TSH           pregnancy. TSH should be measured each        roidism during estrogen
protects other body systems from the                                                       therapy.” N. Engl. J.
                                             trimester so that appropriate thyroxine
                                                                                           Med. 2001; 344: 1743-
effects of hypothyroidism.                   replacement can be determined.                1749.
   If the TSH is within the normal range,    Untreated hypothyroidism increases the
but the person has symptoms suggesting       risks for mother and baby.



                                                                                                                   3
“I had problems on Synthroid
and switched to Armour. I am             Natural or Synthetic?                    Balancing T3 and T4
now in excellent health with lots            Underactive thyroid glands, or          When a thyroid gland is func-
of energy, a cheerful disposi-           “hypothyroid” conditions, are            tioning normally, it puts out two
tion and greatly improved                treated by supplying extra thyroid       different hormones: triiodothyro-
mental acuity and memory. I              hormone. These hormones come in          nine, or T3, and levothyroxine,
also found it easy to lose 7             a wide variety of formulations. Natu-    known as T4. (The numbers indicate
pounds, which I could not do on          ral products include the ground-up       how many atoms of iodine are part
Synthroid.                               dried thyroid glands of cows or pigs.    of the hormone molecule.) Why,
“Armour thyroid has both T3              This “desiccated” thyroid used to be     then, do physicians prescribe only
and T4, whereas Synthroid                the only source of replacement hor-      one, levothyroxine? Even in a
provides only one of these and           mone. It is still available as Armour    healthy person, the thyroid gland
the body is supposed to                  thyroid, but endocrinologists some-      produces only a fraction of the T3
manufacture the other. Is it             times worry about potency chang-         that the body uses. Other tissues in
possible some of us can’t make           ing from one batch to the next. Con-     the body normally convert T4 to the
the other, so Synthroid doesn’t          sequently, many doctors prefer to        more active T3 as they need it, just
work for us? I am living,                prescribe a synthetic, usually           by knocking one of the iodine atoms
bouncing proof that a switch to          levothyroxine, or T4. It is available    off. This works well for most people.
a natural thyroid can work.”             generically or as Synthroid, Levo-          But there are individuals for
                                         throid, Levoxyl or Unithroid.            whom levothyroxine just doesn't
                                             Levothyroxine comes in a wide        seem to do all it should. These people
                                         range of doses. The doctor generally     continue to experience symptoms
“For years I took Thyrolar for hy-       tries to adjust the dose so that each    even on doses of levothyroxine that
pothyroidism. When I had to              patient is taking the smallest           should be adequate. Such patients
change doctors, my new endo-             amount that brings the TSH level         may complain that their previous
crinologist refused to prescribe         into the normal range. Generally,        experience with Armour thyroid was
it. He said the dose is too hard to      hormone specialists recommend            far better and wonder why the phy-
adjust and test results difficult to     starting at a very low dose and          sician does not simply prescribe
interpret. Instead he prescribed         gradually increasing to the desired      dessicated thyroid. Because Armour
Synthroid.                               level. This requires patience and        thyroid contains both T3 and T4,
“In the three years since then, I        persistence as well as good commu-       some endocrinologists, such as Dr.
have gained 25 pounds and am             nication with the doctor and peri-       Ridha Arem, are prescribing it in
tired all the time. I have com-          odic monitoring. Some people may         conjunction with levothyroxine for
plained and had numerous blood           need dose reductions as they age,        patients who may not be converting
tests, but each time the results         especially if they develop heart prob-   T4 efficiently and who continue to
are within normal range. A nutri-        lems.                                    experience symptoms. Dr. Arem
tion expert said I should be taking          Levothyroxine is absorbed best if    cautions that a single dose of Armour
Armour Thyroid because                   it is taken on an empty stomach, so      during the day may result in an
Synthroid robs the bones of cal-         doctors often recommend it be taken      initial surge of T3 and then a drop in
cium.                                    at least a half-hour before break-       the level of this hormone later in the
“When I asked the doctor about           fast. It is particularly important not   day. It does not last long.
this, he said Synthroid is best          to swallow this thyroid hormone at          Other experts have found that
because the dosages are exact            the same time or within an hour of       adding a small amount of T3 to pa-
and testing is more precise.             calcium or iron supplements. These       tients’ levothyroxine can alleviate
Those nice normal test results           minerals can prevent absorption of       depression and mental cloudiness
make my doctor feel good but I           the hormone. The most important          from low thyroid hormone better
still feel lousy.”                       thing is to be consistent in the way     than T4 alone. It is possible that
                                         you take it, so that once the proper     some of these people are not capable
                                         dose has been determined, that is        of converting T4 to T3 efficiently. In
                                         the dose you actually get. Many          one study, researchers found the
*Bunevicius, Kazanavicius,               experts feel it’s best to stick with     dose of levothyroxine that normal-
Zalinkevicius and Prange. “Effects of
                                         the same brand rather than switch-       ized TSH. Then, they replaced 50
Thyroxine as Compared with Thyroxine
Plus Triiodothyronine in Patients with   ing back and forth, because there        mcg of that dose with 12.5 mcg of T3,
Hypothyroidism.” N. Engl. J. Med.        may be some differences in formu-        sold in this country under the brand
1999; 340: 424-429.                      lation that alter absorption.            name Cytomel.*


    4
    Dr. Arem writes that his experi-     Treating Overactive
ence with a T4/T3 combined regimen
has been favorable, especially for
                                         Thyroid Glands
patients who also have depression           An overactive thyroid gland that
or fibromyalgia. He advocates di-        produces too much hormone can be
viding a small dose of T3 even fur-      just as bad for health as one that
ther, so that it can be taken two or     doesn't produce enough. Hyperthy-
three times a day.                       roidism, or thyrotoxicosis, may pro-
   Not all patients require T3 in ad-    duce psychological symptoms, es-
dition to standard levothyroxine         pecially insomnia, nervousness or
(T4). And for some endocrinologists,     anxiety, in addition to physical
the idea of using Armour thyroid,        symptoms like excessive sweating,       Symptoms of
alone or in combination with             rapid heart beat, inability to stand    High Thyroid
levothyroxine, smacks of quackery,       heat, frequent bowel movements,         Activity
or at best fringe medical practice.      increased systolic blood pressure or
But perhaps more doctors will be-        wide pulse pressure, missing or           Fatigue
gin to experiment in collaboration       scanty menstrual periods, and fin-        Insomnia
with patients who continue to suf-       ger tremor. The TSH level in a case       Weakness
fer symptoms of low thyroid despite      of thyrotoxicosis will be very low.       Nervousness
TSH readings in the normal range.        Even the very sensitive IRMA test         Palpitations
Too often such people are told, in       for TSH may not be able to detect it.
                                                                                   Heat intolerance
essence, that their troubles are all        The most common form of hyper-
                                                                                   Eye complaints
in their heads. It is very likely that   thyroid condition is Graves’ disease.
psychological factors do contribute      This is an immune system malfunc-         Increased sweating
to problems such as lethargy in some     tion in which the body produces           Light menstruation
instances. Both doctors and patients     antibodies that attack the parts of       Loose or soft nails
should keep in mind, however, that       the thyroid gland that usually de-        Irritability
a thyroid imbalance can sometimes        tect and attach to TSH. This gives        Rapid pulse
trigger such psychological problems      the gland a false signal that more        Irregular heartbeat
as depression, feelings of low self-     thyroxine is needed and it keeps on       Finger tremor
worth, or anxiety.                       producing more, in a “sorcerer’s          Shortness of breath
                                         apprentice” scenario. In other cases,     Frequent bowel
                                         hyperthyroid conditions may result              movements
Side Effects                             from growths on the thyroid (thy-
                                                                                   Decreased
   There shouldn't be any obvious        roid nodules). Diagnostic procedures
                                                                                         concentration
side effects of thyroxine when the       like ultrasound, CT scan or mag-
                                         netic resonance imaging (MRI) may         Weight loss
dose is properly adjusted. In some-
                                         be needed if nodules are suspected.       Fine, soft hair
one with heart problems, the dos-
                                         Because excess thyroid can lead to        Hair loss
age should be increased very gradu-
ally. If levels are too high, adverse    bone loss, patients who have been         Anxiety
reactions such as heart palpitations     diagnosed as hyperthyroid should          Increased libido
and rapid heart beat, insomnia, ner-     also be followed up with bone den-        Increased appetite
vousness, and higher blood pres-         sity measurements.                        Increased blood
sure may result. Other possible signs       The person with Grave's disease              pressure
of overdose include headache, diar-      should also see an ophthalmologist
rhea, tremor, increased sweating,        for regular eye examinations, be-
changes in appetite, weight loss and     cause as many as half of those with
reduced menstrual flow. Report such      Graves’ disease develop inflamma-
symptoms to your physician               tion in the muscles and other tis-
promptly, as continued overdosage        sues surrounding the eyes. Symp-
may cause serious cardiac or ner-        toms such as redness, soreness,
vous system complications. If you        blurred vision, bulging eyes and
continue to have symptoms of low         aversion to light may all be related
thyroid activity, tell your doctor.      to this autoimmune condition.



                                                                                                         5
                               Treatment of thyrotoxicosis can be surgery is less commonly recommended
                            complicated. Doctors must choose be- for adults except in the case of certain
                            tween surgery, radiation or thyroid-sup- large nodules or in the case of cancer.
We heard a tragic
                            pressing drugs such as Tapazole (me- Look for a surgeon with plenty of experi-
story from a mother
                            thimazole) or propylthiouracil. Each ence.
whose 26-year-old
                            form of therapy has its advantages and          When treatment for overactive thy-
daughter was being
                            drawbacks, and must be tailored to the roid is begun, a beta-blocker like Inderal
treated for an overac-
                            individual patient.                          (propranolol) may be used to treat un-
tive thyroid gland. She
                               Radioactive iodine is usually the treat- comfortable symptoms such as palpita-
was given Tapazole
                            ment of choice for Graves’ disease. Io- tions or rapid heart rate, tremor and
(methimazole) to
                            dine concentrates in the thyroid gland, anxiety. This medicine will not correct
suppress her thyroid,
                            and delivers its dose of radiation there the thyroid problem, though, so thyroid
but she was not told
                            where it is needed. This treatment de- treatment is also needed.
that this drug could
                            stroys thyroid gland tissue and as a
reduce her ability to
                            consequence, it is irreversible. If there is Drug Interactions
fight infection by
                            any question about the accuracy of the
reducing her produc-
                            diagnosis, a different therapy might be There are a number of medicines that
tion of white blood
                            preferred. In addition, most people can interact with thyroid hormone supple-
cells.
                            treated with radioactive iodine for mentation. Abnormal levels of thyroxine
Despite a clear warn-
                            Graves’ will eventually become hypothy- in the blood can affect the metabolism of
ing in the prescribing
                            roid. Like other hypothyroid people, they asthma medicines like theophylline
information to have
                            will need to take thyroxine to supply the (Bronkodyl, Slo-Phyllin, Theolair,
patients report sore                                                     etc.) or aminophylline. Other drugs that
                            hormone their thyroids cannot make.
throat, fever or other
                                The thyroid-suppressing drugs me- interact are listed opposite.
symptoms of infection,
 MEDIC                      thimazole and propylthiouracil are fre- Lithium            (Eskalith,        Lithane,
this young woman was                                                     Lithobid, etc.), used to treat manic-de-
                            quently used to treat hyperthyroidism.
treated for many
MEDICINES sore              The THYROID HORMONE amount pressive disorder, can throw the thyroid
                           CAN dose is adjusted to the lowestWEAKEN BONES?
throats, strep infec-MEDICINES THAT AFFECT T and T levels. gland out of kilter, causing enlargement
                            that results in normal 3
tions, tonsillitis and
                     THYROIDTESTS                              4
                            Methimazole is usually taken once a (goiter), hypothyroid or, rarely, hyper-
gingivitis without a
                            day, so it is more convenient. However, thyroid conditions. Occasionally the heart
blood test. The doctor
                            for pregnant or nursing women, drug amiodarone (Cordarone) will sup-
treating her failed to
                            propylthoiuracil (taken three times press the thyroid gland so that treat-
connect her series of
                            daily) is considered preferable. (Radio- ment is needed. Aredia (pamidronate),
infections with an
                            active iodine treatment is inappropriate for abnormal calcium metabolism, may
adverse effect of her
                            during pregnancy, as it may affect the also alter the thyroid gland's equilib-
treatment for Graves’       MEDICINES THAT AFFECT THYROID TESTS with your pharmacist and
                            infant’s thyroid gland.) Side effects of rium. Check
disease. When she
                            the medications include bitter taste and doctor to make sure any medicine you are
finally was admitted to
                            nausea. Skin rash, joint pain or an in- taking is safe in combination with your
the hospital with
                            crease in temperature may indicate a thyroid hormone.
stomach ache, dizzi-
                            serious reaction; the doctor should be Never discontinue a thyroid hormone
ness, vomiting and
                            notified promptly. Methimazole occa- medication, regardless of which one you
fever, she had a
                            sionally suppresses infection-fighting take, without your physician’s supervi-
severe infection and
                            white blood cells, leading to a series of sion. Most people diagnosed with a thy-
no white blood cells.
                            sore throats or other infections. If this roid problem need treatment for the rest
She died the next day.
                            problem is not detected in time to re- of their lives.
                            verse it, the patient may die. Some people
                            recover from hyperthyroid conditions Thyroid Treatment in Older
                            after a year or two of thyroid-suppress-
                            ing medication, but no thyroid treat- People
                            ment should be discontinued without Thyroid conditions in older adults may
                            close medical supervision.                   be more difficult to detect. For one thing,
                               Surgery to remove excess thyroid tis- some of the symptoms of an underactive
                            sue is another possible treatment. It thyroid, such as fatigue, forgetfulness or
                            requires careful presurgical treatment. constipation, may be accepted by patients
                            Although complications are uncommon, and families alike as inevitable signs of


 6
aging. So might the palpitations, ner-      category of “subclinical hypothyroid-      Thyroid and Iron
vousness or weakness that may be caused     ism.”                                         Millions of people take
by excessive thyroxine.                       The question of whether these people     Synthroid daily, but tak-
  Sometimes older people have unusual       should be treated is extremely contro-     ing 300 mg of the iron
symptoms. Too much thyroid hormone          versial. Experts agree that if there are   supplement ferrous sul-
can cause loss of appetite, congestive      symptoms of an inactive thyroid, treat-    fate at the same time can
heart failure, depression, dementia, apa-   ment with the lowest effective dose of     reduce the effectiveness
thy, constipation or muscle rigidity in     thyroxine is appropriate. Some elderly     of levothyroxine.
elderly persons. Hair loss involving body   people with no initial symptoms even-        Blood tests showed less
and even pubic hair may not be men-         tually develop obvious hypothyroidism      thyroxine circulating in the
tioned or recognized as a possible symp-    that requires treatment. It is crucial     blood stream. Patients
tom of hypothyroidism. The clinical pic-    not to overtreat the elderly, because      who took Synthroid with
ture can be so different from the “text-    heart disease and osteoporosis could       iron also had more symp-
book” picture of thyroid disease that the   both be made worse by overzealous thy-     toms of hypothyroidism,
condition might not even be suspected.      roid treatment. Older people also seem     such as fatigue, menstrual
  Thyroid function tests may show el-       to metabolize thyroxine more slowly,       irregularities and chilling.
evated levels of TSH in older people even   and may need lower doses initiated more     The researchers suggest
when they don't seem ill. In some cases,    gradually than younger patients. This      that “separating the times
levels of free T4 are normal. One study     is especially important if a person al-    at which the two drugs are
discovered around 15 percent of both        ready has some heart disease and is        ingested by 2 or more
men and women over 60 fell into this        taking a medication like digoxin.          hours” might limit this in-
                                                                                       teraction.
                                                                                       [Campbell et al. “Ferrous
   SOME DRUGS THAT INTERACT WITH THYROID HORMONE                                       Sulfate Reduces Thyroxine
                                                                                       Efficacy in Patients with
                                                                                       Hypothyroidism.” Annals of
                                                                                       Internal Medicine 1992;
 Aminoglutethimide               Long-term treatment reduces T3, T4 and raises         117:1010-1013.]
  Cytadren                       TSH
 Antacids
                AME     M        Aluminum or calcium-containing antacids may                Thyroid and
                                 interfere with absorption, reducing effectiveness
 Androgens
                                                                                               Calcium
   testosterone,                 Androgens increase the effects of thyroxine.            Few studies have been
  Halotestin, Testred, etc.      Lower dose (25-50%) may be needed.*                   done to determine if cal-
 Antidepressants                                                                       cium supplements inter-
  Elavil, Tofranil,              Thyroxine increases antidepressant                    act with levothyroxine to
  and other tricyclics           action; more side effects from both drugs.
                                                                                       reduce its absorption.
                                                                                       Three cases have been
  Paxil, Prozac                  Rare reports of thyroid dysfunction
 Asthma medicine                                                                       reported of women whose
  aminophylline, theophylline    Hypothyroid people metabolize these                   thyroid pills (Levothroid,
                                 drugs slowly; with thyroxine, they may need a         Synthroid) became less
                                 higher dose of asthma drug.                           effective, as measured by
 Blood thinners                                                                        blood tests and clinical
   Coumadin                      Anticoagulant action is increased by                  symptoms, when they
                                 thyroxine; dangerous bleeding possible.               were taken at the same
 Cholesterol medicine                                                                  time as calcium carbon-
  Colestid, LoCHOLEST,           These drugs may reduce thyroxine absorp-
                                                                                       ate (Os-Cal and Tums).
  Questran, Welchol              tion. Take at least 4 hours apart.
                                                                                       It’s a good idea to take
 Diabetes medicine               Thyroxine replacement lowers effectiveness.           these two pills four hours
 Epilepsy drugs                                                                        apart.
  Dilantin, Tegretol             These may increase thyroxine requirements.            [Schneyer. “Calcium
 Heart drugs                                                                           carbonate and reduction of
                                                                                       levothyroxine efficacy.” JAMA
   Beta blockers                 An increase in thyroxine may decrease the             1998; 279:750.]
                                  effectiveness of these medicines; beta-blockers
                                  may reduce T4 to T3 conversion
   Digoxin (Lanoxin)             Blood levels of digoxin decrease as levels of                       *
                                                                                       *Arafah. “Decreased
                                 thyroxine increase.                                   Levothyroxine Requirement in
                                                                                       Women with Hypothyroidism
 Interferon alfa                 Long-term use may lead to thyroid antibodies and      during Androgen Therapy for
   Intron A                      thyroid malfunction.                                  Breast Cancer.” Ann. Intern. Med.
 Niacin, slow-release            T4 and thyroxine-binding globulin (TBG) may drop      1994;121:247-251.
                                                                                                                     7
Thyroid Problems in                       for years. Occasionally people with ac-
Children                                  cess to thyroxine will even try to treat      Thyroid Fighting
                                          themselves for such problems, but get-
  Because thyroid hormone is cru-                                                       Foods?
                                          ting thyroid hormone you don’t need
cial for growth and development,          isn’t good for you and can cause signs of      Certain foods contain a
babies are now screened at birth to       hyperthyroidism. To determine if you          chemical that can block
make sure their levels are adequate.      truly need thyroxine that may have been       thyroid hormone. A diet
In parts of the world where iodine is     prescribed originally for unclear reasons,    that relies heavily on one
scarce, cretinism affects some vul-       the doctor may ask you to stop treat-         or more of these can result
nerable children who end up with          ment, and then do a blood test after four     in the development of a
inadequate thyroid hormone in the         weeks. If all blood tests are normal at       goiter, in which the thyroid
womb and from infancy onward. In          that point, the doctor may decide thyrox-     gland grows larger in an
the United States, cretinism has          ine is unnecessary.                           attempt to make more
become a rarity since the introduc-                                                     thyroxine.
tion of iodized salt, which provides
                                          Natural Treatments                            There is no evidence that
an ample amount of iodine in food           Many people would like to find an herbal    these foods interfere with
everywhere in the country.                medicine that would correct thyroid im-       thyroid treatment when
  Neonatal screening discovers the        balance naturally. Although some plant        eaten in normal amounts,
one baby in 4,000 born without            substances can change thyroid function,       but prudence would
enough thyroxine. Treatment with          the results are unpredictable. The resin      suggest moderation in
replacement hormone wards off the         guggul from India, used to lower choles-      consuming:
physical and mental stunting that         terol, is reputed to increase thyroid hor-              broccoli
might otherwise occur. A baby with        mone production, but its utility in treat-              brussels sprouts
severe untreated hypothyroidism           ing hypothyroidism is not known.                        cabbage
may lose three to five IQ points            Some people attempt to treat thyroid                  cauliflower
within the first year of life. In chil-   problems with natural sources of iodine                 millet
dren who develop thyroid insuffi-         such as seaweed. Although some iodine                   mustard greens
ciency after babyhood, one of the         is crucial, large doses of iodine can be                peanuts
earliest signs may be a change in         harmful.                                                radishes
the growth curve. This is one of            The best way to use a more natural                    rutabaga
several reasons for keeping track of      approach to thyroid treatment may be to                 soybeans
a child’s weight and height. As for       integrate Armour thyroid with a syn-                    turnips
adults, treatment requires finding        thetic levothyroxine, as described on page
the appropriate dose of thyroxine,        4. This poses a dilemma for the vegetar-
based on TSH tests.                       ian, however. Armour is derived from         For More Information:
  Children may also develop Grave’s       animal sources. In addition, relying         The Thyroid Foundation of
disease, although this is very rare       heavily on soy as a primary protein source          America, Inc.
in young children. Parents may no-        can also put a strain on the thyroid. A      Ruth Sleeper Hall, Rm. 350
tice emotional disturbances more          prudent limit is three or four servings of   40 Parkman St.
than the physical symptoms typical        soy per week.                                Boston MA 02114
of hyperthyroid conditions in adults.       The minerals selenium (50 mcg) and                   Phones:
Treatment may differ, too, as the         zinc (15 mg) are important for thyroid              (800) 832-8321
long-term safety of radioactive io-       health. If the diet does not contain good           (617) 726-8500
dine treatment in children has been       sources of these, such as whole grains,
questioned. As a result, doctors are      fish, lean beef or soy, a supplement is      Web site:
more likely to recommend thyroid-         recommended.                                 www.about.com/mbody.htm
suppressing drugs or surgery for
children or adolescents diagnosed         If you have questions or comments,           Recommended Reading:
with Grave’s disease.                     feel free to write:                          The Thyroid Solution
 Other Reasons for                        Graedons’ People’s Pharmacy                  by Ridha Arem, M.D.
                                          P.O. Box 52027                               Ballentine Books, 1999.
 Thyroid Treatment                        Durham, NC 27717-2027
  In the past, doctors sometimes pre-     You may also wish to order a CD of our       The Thyroid Book
scribed thyroid hormone for condi-        interview with Dr. Ridha Arem: Call          by Martin I. Surks, M.D.
tions such as obesity or chronic tired-   (800) 732-2334 and request show              Consumer Reports, 1993.
ness, but this has been discouraged       #393. The cost of $15 includes ship-
                                          ping & handling.
 8

				
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