The effects of pyridoxine on pituitary hormone secretion in amenorrhea-galactorrhea syndromes.

Six patients with amenorrhea, five of whom had galactorrhea and elevated PRL levels, were evaluated on a metabolic ward. All had normal sella tomograms, normal thyroid functions, and routine laboratory evaluations. None of the patients had taken any medication in the previous 6 months. On alternate days, five patients received 500 microgram of TRH iv with the measurement of PRL, TSH, FSh, LH, and hGH; 500 mg L-dopa orally with the measurement of PRL, FSH, and LH; a bolus infusion of 300 mg pyridoxine (B6) with measurement of PRL, hGH, TSH, FSH, and LH; and 25 mg chlorpromazine (CPZ) im with the measurement of PRL, LH, and FSH. The patients were then discharged on 600 mg oral pyridoxine/day and were readmitted for a repeat of the complete protocol 21 days later. The patients were continued on 600 mg oral pyridoxine for 3-4 months with monthly evaluations of serum PRL, LH, and FSH levels. These evaluations continued for 3 months after discontinuing pyridoxine. There was no demonstrable change in serum PRL after acute or chronic B6 therapy, mor was there a significant change in the response of PRL to CPZ, L-dopa, or TRH. The mean basal PRL was 97.5 +/- 9.7 ng/ml and after 3-4 months of oral pyridoxine was 97.1 +/- 14.8. In addition, there was no significant change in LH or FSH levels in response to acute or chronic B6, TRH, L-dopa, or CPZ. Neither acute B6 infusion nor chronic B6 therapy had any effect on TSH or the TSH response to TRH. Finally, acute B6 infusion had no effect on hGH levels and there were no paradoxical hGH responses to TRH. Two patients began having regular menses while on chronic pyridoxine. Their hormonal responses did not differ from those of the group, however.