ABSTRACT
In patients with untreated Cushing's disease decreased thyroid function has been demonstrated by several investigators. An inhibiting effect of glucocorticosteroids on the release of thyrotrophin seems to be the cause. In the treated patient with remission of the disease the pituitary-thyroid function has not been studied in detail. The question is, if the hypofunction proved in the untreated state might persist in the treated patient. This might be anticipated from both clinical and experimental studies.
In the present study the pituitary-thyroid function has been determined after total adrenalectomy followed by remission in 14 patients with Cushing's disease. All patients were replaced adequately with cortisone acetate post-operatively as estimated by excretion of cortisol in urine. Levels of serum thyroxine, thyroxine-binding globulin, and serum thyrotrophin were measured. In addition, tracer studies were performed. The 131I-uptake in the thyroid gland and plasma protein-bound radioiodine were determined. After thyrotrophin-stimulation test, the thyroxine reserve and the rise in 131I-uptake in the gland were measured. TRH-stimulation test was performed to determine the TSH-reserve. A normal pituitary-thyroid function and a normal pituitary and thyroid reserve were demonstrated.
In the conclusion it can be said that decreased pituitary-thyroid function or reserve has not been found in the Cushing-patient subjected to adrenalectomy followed by remission. Thus, thyroid replacement therapy has not to be considered, when an adequate replacement therapy is planned after total adrenalectomy.
The Dexamethasone-Suppressed Corticotropin-Releasing Hormone Stimulation Test Differentiates Mild Cushing's Disease from Normal Physiology
