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Disorders of Thyroid Gland.pptx

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					Dr Umar Farooq
Thyroid Physiology

 Thyroid hormone production is under the control of
  thyrotropin-releasing hormone (TRH) and thyroid-
  stimulating hormone (TSH) secretion through a
  negative feedback loop involving thyroxine (T4) and
  triiodothyronine (T3 ).
 Generally low TSH levels reflective of thyrotoxicosis
  and elevated TSH levels indicative of hypothyroidism.
 The thyroid gland primarily produces T4 and only a
  small amount of T3. Most T3 comes from peripheral
  conversion by 5'-deiodinase enzymes.
 Only free forms of T4 and T3 are biologically active.
Thyrotoxicosis

 The term thyrotoxicosis encompasses all forms of
  thyroid hormone excess.
 Primary
 Secondary
 Endogenous
 Exogenous
 Hyperthyroidism specifically refers to thyroid gland
  overactivity.
Causes of Hyperthyroidism
Hyperthyroidism occurs most of times from;

 Graves Disease


 Toxic multinodular goiter


 Toxic adenoma
Sypmtoms
 Severity of symptoms is variable between patients and
    does not always correlate with the extent of thyroid
    hormone elevation
   Symptoms include:
    fatigue
   Anxiety
   Insomnia
   weight loss (despite increased appetite)
   Tremulousness
Sypmtoms(contd;)
 heat intolerance
 irregular menses
 Hyperdefecation
 Palpitations
 shortness of breath or dyspnea on exertion
 muscle weakness
 Compressive symptoms of goitre(dysphagia,dyspnea)
Signs
 Tachycardia,atrial fibrillation
 Tremors
 Excessive sweating of hands
 Anxious face
 Goitre
 Proptosis
 Lid retraction
 Lid lag
 Pretibial edema
Investigations
 TSH
 Free T4
 Free T3 (suppressed TSH but normal FT4)
 Complete blood counts
 Chemistry
 Anti thyroperoxidase and antithyroglobulin antibodies
 Thyroid receptor antibodies
 Thyroid scan with radioactive I131 uptake
Graves Disease

 Autoimmune process characterized by the production
    of antibodies against the TSH receptor
   Antibodies stimulate autonomous thyroid gland
    function
   Risk factors-positive family history, the presence of
    other autoimmune conditions and tobacco use
   Apart from thyrotoxic symptoms patients have;
   a palpable goiter, which is classically smooth
    a thyrotoxic stare due to lid retraction; proptosis; and,
    infrequently, an infiltrative dermopathy
Graves disease-treatment
 Beta blockers for adrenergic symptoms


 Treatment options are;


Drugs
Radioactive iodine
Surgery
Drugs


 Short term-preparation for surgery
 Long term (6-18 month)-an attempt to achieve
  remission
 Remission rate 50 percent after 1 year of therapy
 High remission rate in patients with mild
  hyperthyroidism , small goiter and low dose anti-
  thyroid drug requirements.
Drugs (contd;)
 Propylthiouracil and methimazole are the two
  antithyroidal drugs
 Side effects include rash, elevated liver enzymes,
  agranulocytosis.
 Propylthiouracil has more side effects;so is not first
  line
 First trimester of pregnancy-propylethiouracil
Radioactive iodine
 Treatment of choice in US
 Can effectively ablate an overactive thyroid in greater
    than 90% of patients, characteristically after a single
    dose
   neck pain or tenderness from radiation thyroiditis
   exacerbation in the thyrotoxic state for several weeks
    because of the release of preformed hormone
   Hypothyroidism- within 2 to 3 months of therapy
   Ophthalmopathy can worsen
Surgery
 Reserved for;


 concurrent suspicious nodules


 extremely large goiters


 ophthalmopathy in whom radioactive iodine has
 aggravated their eye condition.
Toxic Multinodular Goiter and
Toxic Adenoma

 one or more palpable nodule(s) and overall gland
  enlargement
 Obstructive symptoms can occur if the gland is large,
  especially if there is any significant substernal
  extension
 Thyroid scan is indicated
 Treatment is with radio active iodine or
  surgery(lobectomy, total thyroidectomy
Hypothyroidism

Clinical syndrome resulting from low thyroxin


Common disorder with a higher prevalence in women
 than men and in persons with other underlying
 autoimmune diseases

Associated with celiac disease, diabetes mellitus
Causes
 Hashimoto thyroiditis is the most common
 Iatrogenic hypothyroidism (from radioactive iodine
  ablation ,external-beam radiation to the thyroid bed or
  surgery)
 Medications - lithium carbonate, interferon alfa,
  interleukin 2, and amiodarone
 Pituitary tumors and/or pituitary surgery can cause central
  hypothyroidism
 Congenital forms of hypothyroidism, such as thyroid
  agenesis or dyshormonogenesis (a genetic defect in the
  synthesis of thyroid hormone)- rarer causes
Symptoms
 Symptoms include;


 Fatigue
 Reduced endurance
 Weight gain
 Cold intolerance
 Constipation
 Impaired concentration and short-term memory,
Symptoms (contd;)
 Dry skin
 Edema
 Mood changes
 Depression
 Muscle cramps
 Myalgia
 Menstrual changes, such as menorrhagia(everything
 slows down except menses!!!)
Signs
 Examination findings include;
 Reduced basal temperature
 Diastolic hypertension
 Possibly enlarged thyroid gland
 Bradycardia
 Pallor
 Dry and cold skin, brittle hair, hoarseness, and a
  delayed recovery phase of deep tendon reflexes
Investigations
 TSH
 Free T4
 anti–thyroid peroxidase antibodies suggests
  Hashimoto thyroiditis as the cause of hypothyroidism
 Anemia
 Hyponatremia
 Increased muscle enzymes
Treatment
 Treament is with thyroxine replacement therpy


 Thyroxine should be taken empty stomach


 Therapy is needed life long


 Yearly monitoring of thyroid functions
Thyroid Emergencies

 Life-threatening conditions associated with thyroid
 disorders include;

 thyroid storm
 myxedema coma
Thyroid storm
 Severe manifestation of thyrotoxicosis associated with
  amplified signs and symptoms coupled with secondary
  systemic decompensation
 precipitating conditions:surgery, infection, trauma,
  myocardial infarction, pulmonary embolism, diabetic
  ketoacidosis parturition, acute iodine exposure,
  radioactive iodine (131I) therapy, or ingestion of
  medications, including salicylates and
  pseudoephedrine
 Treatment includes antithydoid
  drugs,propranolol,steroids,cooling blankets
Myxedema Coma

 Extreme manifestation of hypothyroidism, to the point
  of systemic decompensation
 Precipitating factors- hypothermia, stroke, heart
  failure, infection, metabolic disturbances, trauma,
  gastrointestinal bleeding, acidosis, hypoglycemia, and
  hypercalcemia
 Mental status changes and hypothermia (temperature
  less than 94.0 °F are hallmark
Myxedema Coma(contd;)
 Additional common findings are hypoxemia and
 hypercapnia

 Treatment is with intravenous thyroxin


 Underlying factors should be treated

				
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