Knowledge is essential Applied, it is Wisdom Wisdom is Happiness

1. Knowledge is essential Applied, it is Wisdom Wisdom is Happiness www.drsarma.in

2. Abnormal Thyroid Function A Practical Approach

3. Clinical Exam. of Thyroid • Have patient seated on a stool / chair • Inspect neck – also while drinking water • Examine with neck in relaxed position • Palpate from behind the patient • Remember the rule of finger tips • Use the tips of fingers for palpation • Palpate firmly down to trachea • Pemberton’s sign for RSG

4. Where to look for Thyroid ?

5. Clinical Anatomy of Thyroid

6. Clinical Exam of Thyroid

7. Clinical Exam of Thyroid

8. Thyromegaly

9. Thyroid Gland Hormonogenesis

10. HYPOTHALAMUS - TRH ANT. PITUITARY - TSH THYROID T4 and T3 PLASMA T4 + FT4 PLASMA T3 + FT3 TISSUES FT4 to FT3, rT3 Thyroid Regulation TSH -R

11. In the Thyroid Gland There the following 5 steps in the hormonogenesis • Trapping of inorganic Iodine from dietary Iodides • Activation of Iodine to high valance I2 • Incorporation of I2 into Tyrosine of Thyroid Globulin • Coupling of formed MIT and DIT to form T4 & T3 • Proteolysis of Thyroglobulin to release T4 & T3

12. Metabolism of Thyroid Hormones Thyroid Gland 100 nm Thyroxine FT4 5 nm < 5 nm 45 nm 35 nm Reverse T3 (rT3) Triiodothyronine (FT3) 20 nm Tertrac etc.,

13. Normal catabolism -Thyroxine FT4 FT3 rT3 will be LOW rT3 ÷ T3 ratio will be LOW Normal deiodination of T4 Abnormal catabolism -Thyroxine FT4 FT3 rT3 will be HIGH rT3 ÷ T3 ratio will be HIGH Fluoride affects the normal deiodination of T4 rT3 rT3 What happens in Fluorosis

14. The Thyronines Mono Iodo Tyrosine – MIT Di Iodo Tyrosine – DIT Tri Iodo Thyronine – T3 –half life 6 hours Tetra Iodo Thyronine – T4 half life 7 days Reverse T3 - metabolically inactive T4 is 99.9% protein bound to TBG, TPA, TA T3 is 99.5% protein bound to TBG, TPA, TA Bound hormones are inactive – should not be measured Only Free T4 and Free T3 are metabolically active

15. The Thyroxines Tri Iodo Thyronine – T3 - 10% is from thyroid gland - 90% derived from conversion of T4 to T3 Tetra Iodo Thyronine – T4 - Is exclusively from thyroid gland From the thyroid gland - 80% of hormone secreted is T4 - 20% of hormone secreted is T3

16. Thyroid Function Tests

17. Thyroid Function Tests • TSH • Free T4 • Free T3 • Anti-Thyroid Antibodies • Nuclear Scintigraphy • FNAC of nodule

18. What tests should I order ? • As per the Guidelines of the AACE and ATA, ITS • 1. TSH alone if Hypothyroidism is suspected • 2. TSH and Free T4only if Hyperthyroidism is suspected or for routine evaluation • 3. Free T3 if T3 toxicosis is suspected • 4. For follow-up of treatment only TSH • Don’t order for Total T4 or Total T3 • Never order RIU in pregnancy or lactation

19. Which Lab to choose ? • Depends on the method of estimation of hormones • EquilibriumDialysis is the gold Standard for TSH • Radio-immuno assay - 3rd or 4th gen. RIA is the best • Reliability of ELISA is not adequate • Chemiluminescence immuno assay - CIA is the gold standard for FT4 but expensive and less widely available Choose a lab which offers 3rd or 4th generation RIA method

20. How to interpret results ?

21. The Nine Square Game To evaluate our Thyroid patient As per the AACE and ITS Guidelines

22. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

23. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 EUTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

24. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 PRIMARY HYPOTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

25. BASIC THYROID EVALUATION PRIMARY HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

26. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 SECONDARY HYPOTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

27. BASIC THYROID EVALUATION SECONDARY HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

28. BASIC THYROID EVALUATION SUB-CLINICAL HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

29. BASIC THYROID EVALUATION SUB-CLINICAL HYPOTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

30. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 NON THYROID ILLNESS or NTI LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

31. BASIC THYROID EVALUATION NTI or Pt. on ELTROXIN LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

32. BASIC THYROID EVALUATION PRIMARY HYPERTHYROID NTI or Pt. on ELTROXIN SECONDARY HYPERTHYROID SUB-CLINICAL HYPERTHYROID SUB-CLINICAL HYPOTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 EUTHYROID SECONDARY HYPOTHYROID PRIMARY HYPOTHYROID NON THYROID ILLNESS - NTI LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

33. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 EUTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

34. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 PRIMARY HYPOTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

35. BASIC THYROID EVALUATION PRIMARY HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

36. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 SECONDARY HYPOTHYROID LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

37. BASIC THYROID EVALUATION SECONDARY HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

38. BASIC THYROID EVALUATION SUB-CLINICAL HYPERTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

39. BASIC THYROID EVALUATION SUB-CLINICAL HYPOTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

40. BASIC THYROID EVALUATION LOW NORMAL HIGH FREE THYROXINE or FT4 NON THYROID ILLNESS or NTI LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

41. BASIC THYROID EVALUATION NTI or Pt. on ELTROXIN LOW NORMAL HIGH FREE THYROXINE or FT4 LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

42. BASIC THYROID EVALUATION PRIMARY HYPERTHYROID NTI or Pt. on ELTROXIN SECONDARY HYPERTHYROID SUB-CLINICAL HYPERTHYROID SUB-CLINICAL HYPOTHYROID LOW NORMAL HIGH FREE THYROXINE or FT4 EUTHYROID SECONDARY HYPOTHYROID PRIMARY HYPOTHYROID NON THYROID ILLNESS - NTI LOW NORMAL HIGH THYROID STIMULATING HORMONE - TSH

43. THYROID HORMONES TSH upper limit will soon be revised to 2.5 mU/L

44. T.F.T. in Progressive Hypothyroidism TSH Mild Moderate Severe Normal Range Free T3 Free T4

45. Nucleotide Scintigraphy • I 123 and TC 99m Radio Nucleotide Scintigraphy • This test is not at all required in hypothyroidism • This is only to confirm a hyper functioning thyroid or • To assess whether a nodule is ‘hot’ or ‘cold’ • Never order for this test for hypothyroidism • Similar is the case with FNAC – in hypothyroid goiter • If TSH is high and FT4 is low there is no role for FNAC

46. Thyroid Antibodies • Anti Microsomal (TM ) Antibodies • Anti Thyroglobulin (TG) Antibodies • Anti Thyroxine Per Oxidase (TPO) Ab. • Anti Thyroxine antibodies • Thyroid Stimulating (TSA) Antibodies • High titres TPO Ab in Hashimotos & Reidle’s thyroiditis • Anti thyroxine Ab in peripheral resistance to Thyroxine • TSA (TSI) in Graves’ Hyperthyroidism

47. Current Trends in Dx. and Rx. HYPOTHYROIDISM

48. General Considerations

49. Hypothyroidism • Epidemiology • Most common endocrine disease • Females > Males – 8 : 1 • Presentation • Often unsuspected and grossly under diagnosed • 90 % of the cases are Primary Hypothyroidism • Menstrual irregularities, miscarriages, growth retard. • Vague pains, anaemia, lethargy, gain in weight • In clear cut cases - typical signs and symptoms • Low free T4 and High TSH • Easily treatable with oral Levo-thyroxine

50. Classification