Thyroid hormone economy in normal pregnancy

Thyroid hormone economy was studied in 35 pregnant euthyroid non-goitrous women. PBI was found to be significantly increased by 1.66 ug/100 ml over the control value. Mean PBI value was within normal limits. No alteration in the dialyzable fraction or free thyroxine was found. The absolute concentration of thyroxine was increased. Evaluation of the binding capacity of the carrier proteins in serum showed no change in TBG but an increase in TBPA compared to control levels. (Summary)