Association of Calcium and Phosphate Levels with Incident Chronic Kidney Disease in Patients with Hypoparathyroidism: A Retrospective Case-Control Study

Objective. Reasons for the increased incidence of chronic kidney disease (CKD) in patients with chronic hypoparathyroidism are poorly understood. This study evaluated associations between levels of albumin-corrected serum calcium, serum phosphate, and calcium-phosphate product and the odds of CKD development in patients with chronic hypoparathyroidism. Design. A retrospective nested case-control study of adult patients with chronic hypoparathyroidism who had >= 1 prescription for calcitriol who developed CKD and matched controls who did not develop CKD were selected from the IBM (R) Explorys electronic medical record database. Patients. The study included a cohort of 300 patients for the albumin-corrected serum calcium analysis and 80 patients for the serum phosphate and calcium-phosphate product analyses. Measurements. We examined associations between albumin-corrected serum calcium, serum phosphate and calcium-phosphate product levels, and the risk of devloping CKD (defined as >= 2 outpatient estimated glomerular filtration values <60 mL/min/1.73 m(2) occuring >= 3 months apart or >= 1 diagnostic code for CKD stages 3-5). Results. Individuals who had >= 67% of albumin-corrected serum calcium measurements outside, above, or below the study-defined range (2.00-2.25 mmol/L [8.0-9.0 mg/dL]) had 3.5-, 2.9-, and 2.7-fold higher odds of developing CKD (adjusted odds ratios [95% CI]: 3.46 [1.82-6.56], 2.85 [1.30-6.28], and 2.68 [1.16-6.15]), respectively, compared with patients who had Conclusion. In adult patients with chronic hypoparathyroidism, a higher proportion of albumin-corrected calcium measurements outside of the 2.00-2.25 mmol/L (8.0-9.0 mg/dL) range was associated with higher odds of developing CKD.