Q: I am a 32 year female, married and diagnosed to be suffering from hypothyroidism. It is possibly autoimmune (as my mother also has hypothyroidism). I have been on thyroxine 50 mcg since last 2 years and my thyroid function tests (TFT) last year showed: T3 - 0.83 (ref 0.70-2.50); T4 - 6.97 (ref 5.5-13.5) and TSH - 6.44(ref 0.5-6.5). Presently I am in the 7th week of pregnancy. As soon as I missed my cycle I increased thyroxine to 100 mcg which I took for 4-5 days, and later consulted my endocrinologist, who advised 75 mcg at bedtime and repeat TFT. The report was: free T3 - 2.47 (ref 2.3-4.2); free T4 - 0.94 (ref 0.89-1.8); TSH - 10.72(ref 0.35-5.5). After this I have been taking 100 mcg thyroxine at bedtime. Now I am very apprehensive about the 75 mcg which I have been taking for about a week, is it going to have any adverse effect on the brain development of the fetus. Please advise about the dosage I should be taking and at what time of the day and when should I go for a repeat TFT?

A:There is no statistically significant proof that one week therapy of 75 mcg of thyroxine instead of the proposed 100 mcg perceived by the mother will lead to any adverse CNS development in the fetus of a hypothyroid mother who was preconceptionally and is currently on thyroxine therapy. It will be best to consult your gynaecologist in this regard who should counsel you adequately.