7. Are All Functional Derangements
Identified Correctly ?
Primary Hypothyroidism
Thyrotoxicosis
Euthyroid State
“YES”
Central hypothyroidism: Can be missed
8. • Binding protein related abnormalities
• Endogenous antibodies
Should It Be “Total” or “Free”
Hormone Assessment?
Free Hormones
Pregnancy, OCP use, Liver/Kidney failure
9. To Summarize…
• Under steady state
- TSH is a single most useful
screening diagnostic test
• TSH, T4: Identify all functional
derangements
11. 29 year old lady
Severe tingling and numbness of both upper
limbs, especially hands
Nerve conduction study: Carpal Tunnel
Syndrome
On enquiry,
Constipation, wt gain, menorrhagia, hair loss
Adv: Release surgery
T3: 72 ng/dl [60-180]
T4: 6.5 µg/dl [5.5-12]
TSH: 45.3 µIU/ml [0.3-5.5]
12. At Risk Population
Past history of autoimmune thyroid disease
Positive anti-TPO antibodies
Past history of RAI therapy
Family history of autoimmune thyroid disease
Iodine deficiency area
Drug exposure
13. Clinical Spectrum
Symptoms
Weakness
Dry, coarse skin/hair
Lethargy
Weight gain
Slow speech
Sensation of cold
Thick tongue
Edema
Loss of hair
Dyspnea
Hoarseness of voice
Anorexia
Deafness
Memory impairment
Constipation
Neck swelling
14. Signs
Bradycardia
Dry skin
Puffiness of face
Goitre
Non pitting oedema
Slow speech/movements
Delayed relaxation of
DTR
16. Subclinical Hypothyroidism
Normal T3(FT3) and T4(FT4) with increased TSH
Progression to frank hypothyroidism high in AMA
positive patients.
In patients without goitre, positive AMA, or other
risk factors observe, repeat TSH
17. When To Treat…?
1. Dyslipidemia
2. Goiter
3. +ve anti-TPO
4. Pregnancy
5. Infertility
6. TSH > 10
( Source: 2004 Consensus Study Conducted by the Indian Thyroid Society’ )
7. Neuropsychiatric
manifestations
8. Carpal tunnel syndrome
9. Unexplained hyponatremia
10. Short stature
11. Pubertal problems
18. Treatment
L-thyroxine: preparation of choice
Dose 100 mcg/m2
Long (6 days) half life, once daily dose
Bio availability can change with change in
product and lot
T3 not indicated for chronic management of
primary hypothyroidism
Crude thyroid extract (Ebexid)/Amino acids
– not recommended
19. Determinants Of Thyroxine Requirements
Age of patient
Duration and severity of hypothyroid state
Underlying cardiac disease if any
Concomitant drug therapy
Healthy young patients: Start full dose
Long standing disease, elderly, IHD
Small dose 25mcg/day
Increase by 25 mcg once in 4 weeks
20. Drug Interactions
Phenobarbitone, Phenytoin, Rifampin accelerate
metabolism of LT4
Sucralfate, aluminium hydroxide, ferrous
gluconate/sulfate decrease absorbtion of LT4
Soyabean decrease absorbtion of LT4
Requirements of OAD/ insulin increase in a
diabetic after LT4 treatment
21. Monitoring
Steady state T4: achieved at 6 weeks
Monitor TSH 8-12 weeks after start of
treatment
Once TSH is stable, monitor it every
yearly
Failure to respond very rare; ? Compliance
22. Can Hypothyroidism Be Transient..?
Post partum thyroiditis
De Quervain’s thyroditis
Drugs
Amiodarone, lithium
Autoimmune thyroditis (<5%)
Treat Patients for 6 months
Withdraw treatment, repeat TSH 6-8 weeks after
withdrawing LT4
27. Treatment
Started on Carbimazole 30 mg/day
Returns after 1 month with florid
hypothyroidism
Facial puffiness
Weight gain of 8 kg
Edema feet
TSH: 75 μIU/ml
Reason…?
Silent thyroiditis
29. Causes
Not associated with hyperthyroidism
Subacute thyroiditis
Silent thyroiditis
Postpartum thyroiditis
Thyrotoxicosis factitia
Ectopic thyroid tissue (struma ovarii,
functioning metastatic thyroid cancer).
Anti thyroid drugs: not indicated
Symptomatic treatment
Periodic observation
30. How To Avoid…?
Whenever there is doubt….
No goiter/small goiter
Short duration of symptoms
No features of Graves’
Technitium scan thyroid
RAIU scan
34. 50 year old lady
Symptoms of toxicosis since
4-5 months
Significant weight loss
Diffuse goiter
Staring look
Moderate, inactive
ophthalmopathy
36. Management..
Anti thyroid drugs
Titrating doses of Carbimazole/
methimazole/ PTU
Minimum duration: 1 year
No treatment for ophthalmopathy
37. Why Medical Management…?
Only form of therapy correcting the basic
pathology
Chances of complete cure without
hypothyroidism: Much higher than surgery/
radioiodine therapy
Only treatment when T4 levels are very high
41. Thionamides
Inhibit the oxidation and organic binding of iodide:
intrathyroidal iodine deficiency.
No influence on preformed horrmone release
Large doses of PTU: impair the conversion of T4 to T3
Directly influence the immune response, decline in
antigen presentation, decrease the immune infiltration
and reduces the autoantibody levels
42. Thionamides
Half-life
Carbimazole: 6 hours
Propylthiouracil: 1.5 hours.
Both drugs are accumulated by the thyroid
gland.
A single dose of carbimazole may exert an
antithyroid effect for longer than 24 hours.
Both Carbimazole and PTU cross the placenta;
PTU to a lesser extent.
43. Adverse Effects
Common (1 to 5%)
Rash
Urticaria
Fever
Arthralgia
Rare (<1%)
Hepatitis
SLE-like syndrome
Agranulocytosis.
45. Choosing The Right Drug
Carbimazole
Once a day dosing
Cheaper
Fewer reactions
Rapid normalization of T4
Less effects for further RAI
Propylthiouracil
Thrice daily dosing
Expensive
More serious reactions
Slower
Decreased efficacy
Fulminant hepatic failure
Advantage in:
Pregnancy
Toxic crisis
46. Management Of Graves’ Disease
Initial dose
Carbimazole: 20 to 40 mg/ day.
Propylthiouracil: 150 mg every 8 hours.
β blockers: Relief from adrenergic symptoms
Symptomatic improvement: within the first 2
weeks.
Therapeutic response
Occurs after a latent period: 6-8 weeks
(after glandular hormone stores are depleted).
47. Follow up
Clinical manifestations: 3 weeks
T3, T4 levels: 4-6 weeks
(TSH remains suppressed for many
months after starting treatment).
Dosage: Stepped up/ down depending upon
clinical features and T3, T4 levels.
Dose of Carbimazole gradually reduced to
maintenance dose of 2.5-5 mg (with which TSH
remains within the normal range).
48. Follow up
Once the TSH is normalized, always monitor
with TSH.
Treatment should be continued for at least 6
months after TSH normalization.
Total duration of treatment: 12-24 months.
50. Indications For Surgery…
Severe Graves’ ophthalmopathy
Pregnancy (2nd trimester), if anti thyroid drugs
fail
Very large goiters
Graves’ disease with cold nodules
Not willing for RAI
51. Take Home Message…
Hypothyroidism: Early diagnosis and proper
monitoring; easily treatable
Thyrotoxicosis should be differentiated
from hyperthyroidism
Medical management: To be tried at least for
an year in Graves’ disease
