Prolactin concentration in milk and plasma of puerperal women and patients with galactorrhea.

Prolactin (PRL) concentration was estimated in milk and blood of women with various types of galactorrhea (n = 53) and was compared with lactating (n = 17) and normally menstruating women (n = 36). Mean milk (+/- SD) PRL concentration in lactating women (160 +/- 66 micrograms/l) was similar to that of galactorrhea due to pituitary adenoma (149 +/- 87 micrograms/l, n = 24), thyroid dysfunction (193 +/- 72 micrograms/l, n = 8), functional causes (192 +/- 91 micrograms/l, n = 10) or recent pregnancy (198 +/- 44 micrograms/l, n = 2), but higher than that of sex steroid-induced galactorrhea (85 +/- 53 micrograms/l, n = 9). Plasma PRL concentration in lactating women (208 +/- 102 micrograms/l) was higher than in normal control women (14 +/- 5 micrograms/l) and patients with galactorrhea due to thyroid dysfunction (36 +/- 15 micrograms/l), functional causes (16 +/- 8 micrograms/l), drugs (20 +/- 4 micrograms/l), recent pregnancy (22 +/- 3 micrograms/l) or pituitary adenoma (145 +/- 53 micrograms/l). The milk to plasma PRL concentration ratio was 0.8 +/- 0.4 in lactating women and 1.1 +/- 0.7 in patients with adenoma but significantly higher (p = 99% two-sided) in galactorrhea due to thyroid dysfunction (4.4 +/- 2.1), drugs (3.4 +/- 1.1) or functional causes (12.3 +/- 4.3). Bromocriptine administration reduced PRL in both fluids. It is concluded that in women with galactorrhea milk PRL concentration is similar to that of nursing mothers, but plasma levels of this hormone are significantly lower than that of the latter group in all but the pituitary adenoma related galactorrheas.