Measurement of the integrated concentration of prolactin in normal subjects and patients with hyperprolactinaemia.

To determine whether the fluctuations in the concentration of prolactin in plasma of man affect diagnostic procedures, the integrated concentration of prolactin has been compared with a basal concentration. A continuous sampling apparatus was used to study nine normal subjects and 12 subjects with features of the hyperprolactinaemia syndrome. Small differences were demonstrated, which were, however, neither statistically significant nor likely to influence clinical decisions. It is concluded that single estimations of the concentration of prolactin in blood, taken under resting conditions, are adequate for routine diagnostic use.