Dietary calcium deprivation and secondary hyperparathyroidism in patients treated with chronic dialysis

In 33 patients with end-stage renal disease undergoing chronic dialysis, serum parathyroid hormone (PTH) levels were correlated with serum concentrations and dietary intakes of calcium and phosphate. The average dietary calcium intake (549 +/- 54 mg/24 h) was lower than the recommended dietary allowance. There was a weak correlation between serum PTH and serum calcium concentrations (r = 0.39, p less than 0.03). There was also a significant negative exponential relationship between dietary calcium intake and serum PTH (y = 162e-0.0016x, r = 0.61, p less than 0.002). Likewise, when divided into low calcium (less than 500, 304 +/- 27 mg/24 h) and modest calcium (greater than 500, 809 +/- 56 mg/24 h) intake groups, in the low calcium-intake group, serum PTH (128 +/- 20 pg/ml) was more than 2-fold greater than that in the modest calcium-intake group (53 +/- 8 pg/ml, p less than 0.003). These results suggest that low dietary calcium intake may contribute to the occurrence of secondary hyperparathyroidism in patients with chronic renal failure undergoing chronic dialysis.