Role of 1,25(OH)2D in the genesis of secondary hyperparathyroidism of early renal failure and its use in the prevention of this abnormality.

To clarify the mechanisms of hypocalcemia with renal insufficiency and to gain more insight into the mechanisms of secondary hyperparathyroidism in these patients, an 85-day study was conducted to examine the effect of dietary phosphate restriction on divalent ion metabolism in patients with early renal insufficiency. The study was conducted on four male patients with stable mild renal insufficiency who had creatinine clearances of 55 to 60 mL/min. Our results correspond with those of other studies that indicate that phosphate restriction is adequate to reverse and correct secondary hyperparathyroidism as well as other abnormalities in divalent ion metabolism. Because dietary phosphate restriction appears to exert its effect through the increased production of 1,25(OH)2D, an alternative therapeutic approach would be supplementation of 1,25(OH)2D3 (calcitriol). To test this, another study was conducted evaluating the effect of 1-year therapy with 1,25(OH)2D3 on blood levels of parathyroid hormone (PTH) and on various parameters of bone pathology in patients with creatinine clearances of 15 to 55 mL/min. Our results showed that the use of calcitriol is safe and effective in the management of secondary hyperparathyroidism and bone disease in patients with moderate renal failure.