Alterations in thyroid hormone economy in patients with hydatidiform mole

Abstract

A B S T R A C T 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 'I uptake, absolute iodine uptake, and serum protein-bound-I. 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 To 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 Despite the foregoing evidence of thyroid hyperfunction and hypersecretion of T4, patients with molar pregnancy were neither goitrous nor overtly thyrotoxic. They did display, however, high values of the urinary pigment/creatinine ratio, a possible indication of the presence of a hypermetabolic state.It is concluded that in patients with molar pregnancy, thyroid function and T4 secretion are stimulated, often greatly so, by an unusual thyroid stimulator which is demonstrable in the blood and which is probably of molar origin. The nature of the stimulator, as well as the reasons for both the variability of the increase in TBG which occurs in molar pregnancy and the lack of frank thyrotoxicosis, remain to be clarified.

Human Chorionic TSH (hCTSH, hCT) during Normal or Molar Pregnancy

“…It is also of clinical interest that hyperthyroidism is present in cases of trophoblastic neoplasia (Odell et al, 1963;Kock et al, 1966;Galton et al, 1971;Hershman et al, 1970).…”

Transient Non-Autoimmune Hyperthyroidism of Early Pregnancy

“…The authors speculated that an excessive amount of the extracted molar stimulator was responsible for the hyperthyroidism in both patients that resolved following surgical extirpation of the moles. Galton et al [ 54 ] reported the same year thyroid tests done in 11 patients, before and following the extraction of a molar pregnancy. They confirmed previous studies by Dowling et al [ 55 ] that called attention of the striking abnormalities in several aspects of thyroid hormone economy in three patients with molar pregnancy.…”

Thyroliberin and Gonadoliberin Tests During Pregnancy and the Puerperium

“…Normal TSH responsiveness was an expected phenomenon during pregnancy as, in that condition, free triiodothyronine (T3) and thyroxine (T4) levels remained identical to that of healthy non pregnant women (Malkasian 8c Mayberry 1970;Galton et al 1975). …”