William R. Keye

Physiologic and pathologic profiles of circulating human prolactin.

Abstract These radioimmunoassay studies were designed to test three hypotheses: (1) prolactin plays a major role in regulation of mammary function; (2) in the normal woman, prolactin is not a major obligatory factor in gonadal and menstrual cycle regulation; and (3) assessment of alterations in circulating prolactin concentration in response to stimulatory agents is useful in the evaluation of the hypothalamic-pituitary axis. (1) During pregnancy, serum prolactin increased progressively to term. Suckling resulted in a prompt increase in prolactin concentrations. (2) Daily prolactin determinations during the menstrual cycle revealed no cyclic pattern and no significant daily variation. (3) Increase in prolactin response to TRF in nine patients with idiopathic galactorrhea, eight of whom had amenorrhea, was similar to that observed in normal control subjects. Administration of l -dopa resulted in a decrease in prolactin in normal women, women with idiopathic galactorrhea, women following hypophysectomy, a patient with primary hypothyroidism, and in a patient with a chromophobe adenoma. These data support the validity of the first two hypotheses and suggest that further studies on the response to administration of hypothalamic-releasing factors may be useful clinical tools to distinguish neoplastic from nonneoplastic states.

AMENORRHEA, HYPERPROLACTINEMIA, AND PITUITARY ENLARGEMENT SECONDARY TO PRIMARY HYPOTHYROIDISM

A 22-year-old nulliparous woman presented with primary amenorrhea, primary hypothyroidism, hyperprolactinemia, and radiologic evidence of pituitary enlargement. Investigation demonstrated limited reserves of ACTH and growth hormone. Circulating concentrations of TSH and prolactin were elevated; they increased in response to thyrotropin releasing hormone and decreased following L-dopa administration. After treatment with L-tri-iodothyronine, serum TSH and prolactin levels fell markedly, reserves of growth hormone and ACTH returned to normal, menstrual periods began, and the patient conceived. She experienced an uncomplicated prenatal, intrapartum, and postpartum course. It is thought that this patient represents a distinct clinical entity: a syndrome of amenorrhea, hyperprolactinemia, and pituitary enlargement, all secondary to primary thyroid failure. This syndrome should be distinguished from the Forbes- Albright syndrome, as it is reversible with thyroid replacement therapy. Recognition of this syndrome may thus spare the patient unnecessary, and potentially dangerous, pituitary surgery or irradiation.