[Evolution of levels of free thyroxine and thyrotropin in treated Cushing disease]

Abstract

Objective: Determine the frequency and changes in thyroid hormones in Cushing's disease.

Methods: Free thyroxin and thyrotropin levels were measured in 11 patients (age range 17 to 60 years) with Cushing's disease both before and after resection of the pituitary adenoma.

Results: Free thyroxin levels were low (8.3 to 11.7 pmol/l) in 7 patients. These patients had no clinical manifestations of hypothyroidism. In 4 patients, cure of the pituitary adenoma led to normalization of the thyroid hormones 10 days after operation (13 to 55 pmol/l); in the other cases surgical cure was unsuccessful and thyroxin levels remained low. Cortisol levels were finally normalized in these patients after irradiation of the pituitary, a second pituitary operation, or bilateral resection of the adrenal glands in 2 patients. Normal thyroxin levels were thus achieved. There was no correlation between serum cortisol and free thyroxin.

Conclusion: Thyroid hormones should be assayed regularly in patients with Cushing's disease as a supplementary control of treatment effectiveness.