The effect of vitamin D2 on hypocalcemia in patients under chronic hemodialysis

The effects of vitamin D2 (VD2) on hypocalcemia were studied in 54 hypocalcemic patients (29 males and 25 females) on chronic hemodialysis. Calcium lactate (3 g/day) or VD2 (10,000 IU/day, 50,000 IU/day and 80,000 IU/day) were administered for 4 months in order to correct the hypocalcemia. Serum calcium, phosphate and alkaline phosphatase levels were measured and the effects of VD2 on these parameters of calcium metabolism were followed. 1) Calcium lactate or 10,000 IU/day of VD2 were not effective for the correction of hypocalcemia, while 50,000-80,000 IU/day of VD2 were effective. The effects of VD2 on serum calcium concentrations were dose-dependent, and the normalization of serum calcium concentrations was achieved more rapidly with higher doses of VD2. However, in the group treated with 80,000 IU/day of VD2, many patients developed hypercalcemia, but in the group treated with 50,000 IU/day of VD2, only a few patients did it. From these results, suitable dose (initial and maintenance doses) of VD2 in dialysed patients would be 50,000 IU/day. 2) When the responder group (normal serum calcium levels after 4 months of treatment with 50,000 IU/day of VD2) and the non-responder group serum calcium levels lower than 4.2 mEq/liter on the same condition) were compared, the durations of dialysis were significantly shorter in the former than those in the latter. This fact may suggest that the effects of VD2 administration on hypocalcemia in dialysed patients are partly dependent on the residual renal function concerning the conversion of 25-OH-D3 into 1,25 (OH)2D3.