Dissociation between sleep-related and TRH-induced prolactin secretion in seminiferous tubule failure

Prolactin (PRL) secretion has been measured during sleep and following TRH administration in 8 patients aged 24-39 yr with seminiferous tubule failure and 36 controls. Basal LH levels were 25.7 +/- 14.7 mIU/ml in the patients compared to 11.5 +/- 4.2 mIU/ml in the controls (p less than 0.01) Corresponding FSH levels were 26.2 +/- 10.7 mIU/ml and 5.9 +/- 2.1 mIU/ml (p less than 0.001) Mean estradiol 17B and testosterone levels were similar in the 2 groups. The mean PRL secretion during sleep was 16.5 +/- 11.7 ng/ml in the patients and not different in 11 of the controls (12.4 +/- 3.2 ng/ml). One patient had a mean nocturnal PRL concentration of 44.1 ng/ml. In both groups, the mean sleep related PRL concentration was greater than that during waking hours. The average number of peaks in the 2 groups was similar. In the same patients, the peak PRL response to TRH (200 ug IV) was 81.9 +/- 18.8 ng/ml as compared to 32.1 +/- 10.7 ng/ml in the controls (p less than 0.001). It is concluded that PRL concentrations following pharmacological stimulation are increased in seminiferous tubule failure, whereas levels are normal in relation to the physiological stimulus of sleep.