Acquired prolactin deficiency in patients with disorders of the hypothalamic-pituitary axis

Acquired PRL deficiency occurs when the anterior pituitary is functionally destroyed, and it usually accompanies other pituitary hormone deficiencies. We retrospectively investigated in an outpatient endocrine clinic of a major tertiary medical center the prevalence and clinical characteristics of acquired PRL deficiency in patients with diseases of the hypothalamic-pituitary axis. The study included 100 consecutive patients, 61 men and 39 women, aged 4–79 yr at diagnosis. Patients were divided by PRL level to normal (>5 ng/ml), mild (3–5 ng/ml), and severe deficiency (<3 ng/ml). Twenty-seven patients (27%) had PRL deficiency, 13 mild deficiency and 14 severe deficiency. Patients with severe PRL deficiency tend to be younger at diagnosis (mean age, 37.5±21.8 yr) than patients with normal PRL (46±18.5 yr; ns). Underlying diseases including pituitary apoplexy, non-functioning pituitary adenoma, craniopharyngioma, and idiopathic hypogonadotropic hypogonadism were associated with PRL deficiency. The incidence of severe PRL deficiency rose with an increase in the number of other pituitary hormone deficits (ACTH, TSH, gonadotropin, vasopressin), from 0 in patients with no other deficits to 38% in patients with 4 deficits (p=0.006). Patients with severe deficiency had a mean of 3 hormone deficits compared to 1.8 in the other groups (p=0.006). PRL deficiency was significantly associated with TSH, ACTH and GH deficiency. Conclusions: PRL deficiency is common in patients with hypothalamic-pituitary disorders, especially pituitary apoplexy and craniopharyngioma. Acquired severe PRL deficiency can be considered a marker for extensive pituitary damage and a more severe degree of hypopituitarism.