Treatment of clinically overt or subclinical or latent hypothyroid state in pregancy.

·         What are  the Normal TSH variations in Pregnancy?? What changes in TSH value occur in occur in early months Pregancy ?? Ans:- Fall  of TSH:-Serum TSH level falls in the 1st trimester of normal pregnancies as a physiological response to the stimulating effect of HCG on the TSH receptor with a peak HCG level between 7 and 11 weeks . In effect TSH level can be as low as .03 or even undetectable in early pregnancy as thyrotrophic activity of HCG can suppress TSH. Target trimester specific targets are:

.1 to 2.5 in first trimester

.2 to 3 in 2nd trimester

.3 to 3 mIU/Lin 3rd trimester

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·         Q. 2: When Free T4 also?? Ans:-If subnormal then only asses with serum FT4 and  any subnormal TSH value should be evaluated in conjunction with serum FT4 level,

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·          Q.3: When does suspect hyperthyroidism?? Ans:-The diagnosis of clinical hyperthyroidism is made in the presence of suppressed or undetectable TSH & an elevated FT4 level

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Q. 4;  TPO antibodies in our poor country-How relevant?? Few points on TPO antibodies. subclinical hypothyroidism:- Does women in preg who exhibit normal T3 and T4  warrant replacement?? Ans:- Yes. Subclinical Hypothyroidism ( SCH) during pregnancy is defined as TSH between
2.5 & 10  mIU/L with a normal FT4 level... In this situation  one should insist on   TPO antibodies

This is subclinical hypothyroidism and warrant treatment. Goal in pregnancy is to keep TSH below 2.5 especially in first trimester and in second trimester. This is Second trimester TSH value should be less than 3.0. The foetus is totally dependent on maternal thyroxine till 12 weeks because the fetal thyroid starts functioning only after 12 weeks. Deficiency earlier to that can lead to mental retardation. Subclinical hypothyroidism n needs treatment with thyroxine. No harm if we initiate thyroxine at 62,5 mcg initially because  of the fact that thyroxine has a wide safety factor and should be started for subclinical hypothyroidism to avoid foetal mental developmental compromise if there be any. American Thyroid association ( ATA) recommends that newly diagnosed cases of SCH be tested for TPOAb .. Therefore in summary, women who are +ve for TPOAb & have SCH should be treated with LT4....

Q. 5 :-Advantage for thyroxine like Vit D:-- Thyroxine has a wide safety factor and should be started for subclinical hypothyroidism

 Q.6 - Take home message:-Elevation of TSH during pregnancy should be defined using pregnancy specific ranges and clinician will have to  adjust the dose as per TSH &Free T4 ranges once replacement therapy is initiated.

Q.7. .What is Overt Hypothyroidism ( OH)..??.Any TSH > than 10 mIU/L irrespective of FT4 level or elevated TSH value ( > than 2.5) together with decreased FT4 level is known as Overt Hypothyroidism ( OH). European thyroid Association ( ETA) & Indian thyroid Association ( ITS) recommends treating newly diagnosed SCH during pregnancy with LT4 ( thyroxine) ...
( starting dose of 1 to 1.2 microgram / Kg / day is advised in cases of SCH = if we consider an Indian woman weigh on an average 60 kg it comes to 62.5 mcg to 75 mcg .)