Labels:text | screenshot | black and white | black | font | book | document OCR: foetal Between the eighth and twelfth weeks o ry development, the thyroid and the pituit lly. By the differentiate histologically and function Ice twelfth week, the thyroid begins to prod Ing hormone. Serum T4 and thyroxine-bind allel, to globulin (TBG) levels rise rapidly, in par cond plateau at term levels by the end of the s etectable, trimester, Serum T3 levels are low, but d Than in the third trimester and remain lower resulting maternal levels even at term (Fig. 15.4), of T4 to T3. from a low foetal peripheral conversion e to adult Tissue levels, especially brain T3, are clo ational age levels. TSH is detectable at the same gest term as circulating T4. Levels of TSH approac the foetusvalues by sixteen weeks and are higher i I serum. than in normal childhood or in matern sent and Foet ...
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