Diagnosis of Sheehan's syndrome using a sequential pituitary stimulation test

Systematic pituitary evaluation was performed in four patients suspected of having Sheehan's syndrome. A sequential pituitary stimulation test, consisting of insulin-induced hypoglycemia followed by stimulation of gonadotropin-(GnRH) and thyroid-releasing hormone (TRH), a metyrapone test, and adrenocorticotropic hormone (ACTH) stimulation test, was performed. All four patients failed to develop a normal increase in serum growth hormone, cortisol, and prolactin (PRL) following insulin-induced hypoglycemia. All patients demonstrated a blunted PRL, follicle-stimulating hormone, and luteinizing hormone response to the combination of GnRH and TRH. Although thyroid stimulating hormone (TSH) response was impaired in all patients, two patients had normal T3 resin uptake and thyroxine, demonstrating minimal TSH reserve maintaining normal baseline free thyroxine index. Metyrapone administration was followed by no increase in 11-deoxycortisol or 17-ketogenic steroids, thereby adding no additional information to the hypoglycemia stimulation. ACTH infusion revealed normal adrenal cortisol response. In conclusion, in patients with suspected postpartum hypopituitarism, a complete pituitary function investigation can be done in a short time by using the described pituitary sequential stimulation test.