Association of Hypocalcemia With Mortality in Hospitalized Patients With Heart Failure and Chronic Kidney Disease

Abstract

Background: Chronic kidney disease--mineral and bone disorders (CKD-MBD) are associated with vascular calcification and abnormal electrolytes that lead to cardiovascular disease and mortality. CKD-MBD is identified by imbalances in serum calcium (Ca), phosphate, and parathyroid hormone (PTH). Although the relation of phosphate and PTH with the prognosis of HF patients has been reported, the association of Ca with prognosis in patients with heart failure (HF) and CKD remains unclear.

Methods and results: We examined 191 patients admitted for HF and CKD (estimated glomerular filtration rate <60 mL min(-1) 1.73 m(-2)), and they were divided into 2 groups based on levels of corrected Ca: low Ca (Ca <8.4 mg/dL; n = 32) and normal-high Ca (8.4 ≤Ca; n = 159). We compared laboratory and echocardiographic findings, as well as followed cardiac and all-cause mortality. The low-Ca group had 1) higher levels of alkaline phosphatase (308.9 vs. 261.0 U/L; P = .026), 2) lower levels of 1,25-dihydroxy vitamin D (26.1 vs. 45.0 pg/mL; P = .011) and hydrogen carbonate (22.4 vs. 24.5 mmol/L; P = .031), and 3) a tendency to have a higher PTH level (87.5 vs. 58.6 pg/mL; P = .084). In contrast, left and right ventricular systolic function, estimated glomerular filtration rate, urine protein, phosphate, sodium, potassium, magnesium, and zinc did not differ between the 2 groups. In the Kaplan-Meier analysis, cardiac and all-cause mortality were significantly higher in the low-Ca group than in the normal-high-Ca group (P < .05). In the multivariable Cox proportional hazard analyses, hypocalcemia was an independent predictor of all-cause mortality in HF and CKD patients (P < .05).

Conclusions: Hypocalcemia was an independent predictor of all-cause mortality in HF and CKD patients.

Keywords: Heart failure; chronic kidney disease; chronic kidney disease-mineral and bone disorders; hypocalcemia; prognosis.