A predicted case with neonatal transient hypothyroidism due to blocking type thyrotropin binding inhibitor immunoglobulins (TBII).

A 26-yr-old female with primary hypothyroidism due to potent blocking type thyrotropin binding inhibitor immunoglobulins (TBII) was advised of the high risk of bearing a baby with neonatal transient hypothyroidism. This prediction proved valid and her baby was found to be hypothyroid with a potent TBII. By expressing the baby's TBII as the absolute concentration, we found an almost linear regression of TBII and the half-life was calculated as 18.0 days. The TBII became undetectable by the 6th month and thyroid medication was stopped, however the baby remained euthyroid with subsequent normal physical and mental development.