Hyperprolactinaemia is associated with a higher prevalence of pituitary–adrenal dysfunction in non-functioning pituitary macroadenoma

In non-functioning pituitary macroadenoma (NFMA), hyperprolactinaemia (hyperPRL) is considered to be a sign of hypothalamic-pituitary dysregulation, but it is unknown whether hyperPRL is associated with an increased frequency of pituitary hormone deficiencies. Forty consecutive patients with histology-proven NFMA were studied and hyperPRL was defined as serum prolactin (PRL) >200 mIU/l in men and >600 mIU/l in women. The pituitary-adrenal axis was evaluated by measurement of urinary free cortisol (N=38), peak cortisol to insulin-induced hypoglycaemia (IIH, N=36) and to human corticotrophin-releasing hormone (hCRF, N=40) and by urinary tetrahydro-11-deoxycortisol (H4S, N=39), plasma androstenedione increment (N=39) and serum 11-deoxycortisol (N=1) after metyrapone. Central hypothyroidism, gonadotrophin deficiency and growth hormone (GH) reserve were also assessed. Twenty patients had hyperPRL (serum PRL 331 (223-1120) mIU/l (median, range) in men and 932 (660-3927) mIU/l in women); urinary free cortisol excretion (p