Chronic kidney disease (CKD) impairs kidney function, which often causes deficient levels of vitamin D, many times leading to secondary hyperparathyroidism (SHPT). Vitamin D insufficiency has also been associated with increased mortality in CKD patients. OPKO Health has shown that the drug Rayaldee (calcifediol), a modified-release formulation of 25-hydroxyvitamin D3, is a promising treatment for SHPT in patients with moderate forms of CKD.

OPKO’s study, “Treatment Effects of Modified-Release Calcifediol on Bone Markers Suggest Higher 25-Hydroxyvitamin D Levels Are Needed for Adequacy in Patients with Stage 3 or 4 CKD” was recently presented via poster at the Endocrine Society’s (ENDO 2016) 98th Annual Meeting in Boston.

SHPT affects 40 to 60 percent of CKD patients with moderate altered kidney function, clinically defined as stages 3 or 4, and approximately 90 percent of patients with severe CKD (stage 5). The excessive amounts of parathyroid hormone (PTH) secreted by CKD patients stimulates their bones to release calcium and phosphorus, which consequently increase in the patients’ serum.

Also a result of vitamin D deficiency and increased bone metabolism, CKD patients have softening of the bones, a process known as osteomalacia, and calcification of vascular and renal tissues.

The data from 429 subjects presented in this meeting showed that Rayaldee decreased the mean plasma levels of intact PTH (iPTH) and other markers of elevated bone metabolism. It increased vitamin D prohormone, known as 25-hydroxyvitamin D (25D), to levels above the 30 ng/mL, considered to be the threshold of vitamin D insufficiency.

These levels were previously thought to be sufficient for CDK patients in published clinical practice guidelines. However, the authors found that decreases in both plasma iPTH and bone markers were maximal at serum 25D levels above 60 ng/mL. No association was apparent between serum calcium or phosphorus and 25D levels rising to greater than 80 ng/mL.

These data revealed that serum 25D levels recommended for non-CKD patients are insufficient to control SHPT in stage 3 or 4 CKD, and that higher but more effective levels (greater than 60 ng/mL) can be safely achieved with Rayaldee.

Rayaldee’s use in the treatment of stage 3-4 CKD patients with vitamin D insufficiency is pending FDA approval.