Persistent pituitary-thyroid dysfunction patients following renal transplantation

Pituitary-thyroid function, which is known to be altered in patients with chronic renal insufficiency, has been evaluated after successful kidney transplantation in 36 patients and compared with that in 15 healthy subjects. Thyrotropin (TSH) response to thyrotropin-releasing hormone (TRH) was in the low range of normal in 24, and markedly decreased in 12 patients (< 0.0005). In the former group serum thyroxine was normal, whereas triiodothyronine was lowered; in the latter group thyroxine, although within the normal range, and triiodothyronine levels were reduced when compared with that of healthy controls. This differential TSH response to TRH was unrelated to kidney transplant function, duration of renal insufficiency or duration of the preceding hemodialysis, or to the dose and dosing schedule of prednisolone therapy. However, a slight negative correlation between the dose of prednisolone administered and TSh responsiveness to TRH as well as serum triiodothyronine was established (P < 0.05). Thus, corticoid treatment may in part be responsible for the alteration in TSH secretion and in the peripheral conversion of thyroxine to triiodothyronine. Other, as yet undefined factors, such as patients' variability in pituitary susceptibility to the polypragmatic therapy administered, have to be suspected as the major causes of the persistent pathological pituitary-thyroid function tests observed after renal transplantation.