Diagnosis and management of mineral metabolism in CKD

BACKGROUND: Chronic kidney disease (CKD) affects over 26 million Americans and is frequently complicated early in its course by disordered mineral metabolism and metabolic bone disease. Since CKD-related bone loss is often indistinguishable from osteoporosis by standard bone densitometry, many CKD patients may be inappropriately treated with bisphosphonates rather than CKD-specific therapies. OBJECTIVE: To determine the prevalence of appropriate evaluation, diagnosis and management of metabolic bone disease among individuals with pre-dialysis CKD. DESIGN AND PARTICIPANTS: Retrospective cohort study using electronic medical records of 69,215 ambulatory patients seen in the primary care clinics of an academic medical center. MEASUREMENTS: Prevalence of CKD stages 3-4, frequency of diagnostic testing and treatment of metabolic bone disease. MAIN RESULTS: Based on current diagnostic criteria and consistent with national data, CKD was present in 12% of the population. Bisphosphonates were used in 7.2% of patients, 20% of whom met criteria for CKD. Fewer than half of CKD patients underwent testing for parathyroid hormone (PTH) or 25-hydroxyvitamin D (25D) levels. Among those tested, vitamin D deficiency (25D <30 ng/ml) and secondary hyperparathyroidism (PTH >60 pg/ml) were present in 65% and 55%, respectively. Among patients with CKD, bisphosphonate use was nearly seven times as frequent as therapy with active vitamin D (12% vs. 1.7%, p∈<∈0.0001), a primary treatment for CKD-associated metabolic bone disease. CONCLUSIONS: Disordered mineral metabolism in CKD is common, under-diagnosed and under-treated. As a result, bisphosphonates may be prescribed inappropriately in patients with CKD.