Alterations in thyroid hormone economy in patients with hydatidiform mole

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Abstract

Studies of several aspects of thyroid hormone economy have been conducted in 11 patients before and after removal of a molar pregnancy. Before evacuation of the mole, all patients demonstrated moderately to greatly elevated values for thyroidal 131I uptake, absolute iodine uptake, and serum protein-bound-131I. Values for serum PBI and serum thyroxine (T4) concentration were consistently and often greatly increased, averaging more than twice those found in normal pregnancy and three times those in normal controls. On the other hand, the maximum binding capacity of the T4-binding globulin (TBG) was variably affected, and ranged between the values found in normal controls and those found in normal pregnancy. Values for the absolute concentration of free T4 in serum were, on the average, only moderately elevated, since the proportion of free T4 was moderately low, although not as low as in normal pregnancy. Sera of patients with molar pregnancy contained high levels of thyroid stimulating activity, as assessed in the McKenzie mouse bioassay system. The stimulator displayed a more prolonged duration of action than that of TSH and did not reveal a major immunological cross-reactivity with either human or bovine TSH, differing in the latter respect from the chorionic thyrotropin of normal human placenta. Abnormalities in iodine metabolism were rapidly ameliorated after removal of the molar pregnancy, and this was associated with the disappearance from serum of the thyroid stimulator.

Authors

Valerie Anne Galton, Sidney H. Ingbar, Jesus Jimenez-Fonseca, Jerome M. Hershman