Daily requirement for pyridoxine supplements in chronic renal failure

Vitamin B6 deficiency was evaluated in 37 patients with chronic renal failure and in 71 patients undergoing maintenance hemodialysis (HD) or intermittent peritoneal dialysis (PD). Vitamin B6 deficiency was assessed by the in vitro activity of erythrocyte glutamic pyruvic transaminase (EGPT), without (basal) and with (stimulated) the addition of pyridoxal-5-phosphate to the assay, and the EGPT index (stimulated activity ./. basal activity). Basal and stimulated EGPT activities were below normal in the HD patients, and the EGPT index was increased in each group of patients, indicating vitamin B6 deficiency. Supplemental pyridoxine hydrochloride was given to 30 HD patients who received 1.25 to 50 mg/day (37 studies), 6 PD patients who were given 1.25 or 2.5 mg/day (7 studies), and 8 nondialyzed patients with mild to severe renal failure who received 2.5 mg/ day. In all HD patients, 10 or 50 mg/day of pyridoxine hydrochloride rapidly corrected the abnormal EGPT index and maintained normal values; with supplements of 5.0 mg/day or less, the index was often abnormal, particularly in those who were septic or taking pyridoxine antagonists. In PD patients and nondialyzed patients with renal failure, 2.5 mg/day of pyridoxine hydrochloride was inadequate to correct rapidly the abnormal index in all patients. These findings suggest that HD patients should receive 10 mg/day of supplemental pyridoxine hydrochloride (8.2 mg/day pyridoxine). PD patients and patients with chronic renal failure should receive about 5.0 mg/day of supplemental pyridoxine hydrochloride (4.1 mg/day pyridoxine). When sepsis intervenes or vitamin B6 antagonists are taken, 10 mg/day of pyridoxine hydrochloride may be a safer supplement for all patients.