Nonpuerperal lactation and normal prolactin regulation

Prolactin secretion was evaluated in 11 consecutive patients referred with nonpuerperal lactation who did not have clinical evidence of pituitary tumors. Six patients had normal fasting prolactin (PRL) levels, 13.8 plus or minus 1.8 ng per ml (Group I), and the other 5 women had elevated basal serum PRL concentrations, 182 plus or minus 72 ng per ml (Group II). All Group II patients had amenorrhea; however, 5 of 6 Group I patients had menstrual periods. The 24-h mean serum PRL concentrations were 12.8 plus or minus 1.2 (SEM), 13.3 plus or minus 0.7, and 165 plus or minus 62 ng per ml for the controls and Group I and II, respectively. A pattern of intermittent PRL discharge during the day characterized each group; however, a normal sleep related increase in serum PRL concentration was absent in the Group II patients. Chlorpromazine produced greater than two-fold increases in serum PRL concentrations in the controls and Group I patients; however, this response was absent in Group II. L-Dopa produced appropriate suppression of serum PRL concentrations in the normals and both patient groups. Normal serum growth hormone, thyroxine, and plasma cortisol characterized each group. Serum estrogen and/or LH and FSH were decreased in 3 of 5 Group II patients; however, the serum concentrations of these hormones were normal in 5 of 6 Group I patients. Short term L-dopa therapy was effective in suppressing lactation in 3 of 5 Group II patients, and it also decreased lactation in the 4 treated Group I patients without significantly altering 24-h mean serum PRL concentrations in the latter group.

hypothalamic-pituitary dysfunction was present in certain patients with nonpuerperal lactation who had elevated 24-h mean PRL concentrations and no PRL release following chlorpromazine and sleep. Frequently, however, nonpuerperal lactation is associated with normal prolactin secretion.