Thyroid function Tests by hcj

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									Thyroid: Clinical Cases

           Dr Sunil Zachariah
           Consultant Endocrinologist
           East Surrey Hospital
   Thyroid is the only source of T4
   Thyroid secretes 20% of T3, remainder
    is generated in extraglandular tissues
    by conversion of T4 to T3
Normal range
   FT4   11.5-23 pmol/l
   fT3   3-6.7 pmol/l
   TSH   0.3-5.5 mu/L
Case 1
   Female aged 40 years
   Palpitations, weight loss and mild
    proptosis
   Smallish smooth goitre
   FT4 80
   TSH<0.01
Graves Disease
   TSH receptor
    antibodies
   Carbimazole
   Propylthiouracil
   Treatment schedule
   ?Block and replace
   Permanent cure
Case 2
   Female aged 76 years
   Gradual weight loss
   Solitary thyroid nodule
   FT4 32
   TSH<0.01
Management toxic Nodule
   Radioactive iodine
   ?FNA first if palpable nodule as low risk
    of malignancy in toxic nodule
Case 3
   60 year old female
   6 weeks post radioiodine treatment
   FT4 11
   TSH 0.02
Post radioiodine thyroid function

   Check 6 weeks after treatment
   TFTs may fluctuate
   50% risk of hypothyroidism
Case 4
   Female aged 79 years with fast AF
   FT4 19.5
   TSH 0.2
   This case probably not for antithyroid
    treatment
   If overtly hyperthyroid treat
   Subclinical hyperthyroidism: Normal
    FT4, Low TSH
   Risk factor for Atrial fibrillation,
    osteoporosis
Case 5
   50 year old man
   Ventricular tachycardia with poor LV
    function
   Controlled on Amiodarone
   FT4 50
   FT3 7
   TSH<0.01
Amiodarone and Thyroid
   Inhibits thyroidal iodide uptake
   Inhibits conversion of T4 to T3
    intracellularly
   Inhibits T4 entry into cells
   Direct T3 antagonism at level of cardiac
    tissue
What does it do to TFTs?
   Early[1-10 days]: TSH increase, FT3
    decrease, then Ft4 increase after 4 days
   Later[1-4 months]: Ft4 increase by
    40%, FT3 remains low or normal, TSH
    levels normalise
   Long term: TSH may suppress
Amiodarone induced hyperthyroidism


   2-12%
   Type 1: Iodine overload in abnormal gland,
    treat with carbimazole or lithium
   Type 2: Glandular damage, release of
    preformed hormones, treat with prednisolone
    0.5-1.25 mg/kg for 3-6 weeks
   Management of tachyarrhythmia's: beta
    blockers if not in CCF
   ?total thyroidectomy (not radioiodine)
Case 6
   30 year old female
   Recent flu
   tender enlargement thyroid
   FT4 28
   TSH<0.01
De Quervains thyroiditis
   Recheck TFTs-probably hypothyroid by
    then
   Thyroid antibodies and ESR
   Thyroid scintigram-reduced uptake
   Symptomatic treatment with NSAIDs
   Warn the possibility of recurrence
Case 7
   Female age 25 years
   Hyperpyrexia
   ITU admission
   Profound muscle weakness requiring
    ventilation
   FT4 210
   TSH<0.01
Thyrotoxic crisis
   Carbimazole 60-100 mg via NG tube
   Propranolol infusion
   Profound myopathy and even
    neuropathy can be associated with
    Grave’s
Case 8
   65 year old male
   Pre coronary artery bypass surgery
   Routine blood tests
   FT4 3 mU/L
   TSH 40 pmol/L
Management hypothyroidism with Coronary
artery disease

   May need to put in stents to allow
    introduction of triodothyronine and then
    thyroxine
   Some patients symptomatic when
    thyroxine started/increased
Case 9
   Female aged 32 years
   Weight gain and thyroid
   FT4 13
   TSH 5.5
Sub clinical hypothyroidism
   TSH>10
   Antibody positive
   Family history
   Symptomatic
   Monitor TFT 6 monthly
Case 10

   Hypothyroid on replacement thyroxine
    300 mcg
   FT4 23
   TSH 15
Hypothyroidism requiring high dose
replacement

   Check tablets each visit-check
    compliance
   Check for malabsorption but unlikely
   Probably continue to see but at
    infrequent intervals
Case 11

   Female aged 60 years
   Found collapsed at home
   History of epilepsy
   TFT checked in Causality
   FT4 8.5
   TSH 4.0
Low FT4, normal TSH
   Sick euthyroid
   Possibly hypopituitary-cortisol/FSH/LH
   Check medication-can be secondary to
    carbamazepine
Sick Euthyroid syndrome
   Non thyroidal illness syndrome
   Low FT4 and T3
   Inappropriately normal/suppressed TSH
   Context: Starvation, ITU, severe
    infections, renal failure, cardiac failure,
    malignancy
Case 13
Female aged 34 years
 Secondary amenorrhoea

 Low TSH

 Low FT4
Hypopituitarism
   FSH/LH/Prolactin/cortisol
   MRI Pitutary; ?empty fossa ?large
    adenoma
   Start hydrocortisone first if needed,
    before thyroxine replacement
Case 14
   22 year old female
   Admitted with hyper emesis gravidarum
   Pulse 110 bpm
   FT4 29
   TSH<0.01
Management
   Usually HCG induced in which case it
    will resolve spontaneously by around 14
    weeks
   If positive thyroid antibodies or history
    of grave’s disease then treat with PTU
Case 14
   A] Palpitations, 10 weeks post partum
   Ft4 32
   TSH 0.2
   B] Tired, 10 weeks post partum
   FT4 9
   TSH 8
POSTPARTUM THYROIDITIS

   Incidence varies from 5-11%
   More common in women with a family
    history of hypothyroidism and positive
    TPO antibodies
CLINICAL FEATURES

   Presentation is usually 3-4 months
    postpartum
   Can be hypothyroidism (40%),
    hyperthyroidism (40%) or
    biphasic(20%)
   Goiter is present in 50% of patients
Pathogenesis

   Destructive autoimmune thyroiditis
    causing first release of thyroxine and
    then hypothyroidism as the thyroid
    reserve is depleted
   FNAC shows lymphocytic thyroiditis
Diagnosis
   Advise routine TFT in females who have
    positive TPO antibodies and type 1
    diabetes
   To distinguish from Graves disease use
    thyroid isotope scan and TSH receptor
    Ab
Management
   Most patients recover spontaneously without
    requiring treatment
   If hyperthyroid use beta blockers rather than
    antithyroid drugs as the problem is increased
    release, not synthesis
   Hypothyroid phase is more likely to require
    treatment
   Only 3-4% remain permanently hypothyroid
   10-25% will recur in future pregnancies
Case 15

   Female aged 30 years
   New Thyroid enlargement
New Thyroid swelling
   FNAC if nodule size>1 cm
   Repeat FNAC in 6 months
   Impossible to differentiate between
    benign and malignant follicular
    neoplasm using FNAC
Case 16

   Long standing goitre
   FT4 28
   TSH 7
Measurable TSH with raised FT4

   Heterophile antibodies
   TSH resistance syndromes
   TSH oma-very rare
Thyroid hormone resistance
   Syndrome characterized by reduced
    responsiveness to elevated circulating
    FT4 and FT3, non suppressed TSH
   Short stature, hyperactivity, attention
    deficit
   Differential diagnosis includes TSH
    secreting pituitary tumour
Case 17
   27 year old female
   Follicular Cancer of Thyroid
   Post surgery, post radioiodine ablation
   On Thyroxine replacement (175 mcg)
   FT4 19.8
   TSH 0.05
Follow up of thyroid Cancer
   Original diagnosis and treatment
   If total thyroidectomy and ablative
    radioiodine, thyroglobulins usually
    undetectable if TSH unrecordable
   Maintain TSH<0.05

								
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