Incidence, etiology, and course of hypercalcemia-induced AKI in a tertiary care center from northern India

Abstract
Background
Hypercalcemia is known to cause acute kidney injury (AKI). Literature related to hypercalcemic AKI is predominantly in the form of case reports and case series. The purpose of this study is to find the incidence, etiology, and course of hypercalcemia-induced AKI in a non-critical care setting. To our knowledge, this is the first study done to look for the incidence, etiology, and course of hypercalcemia-induced AKI in a non-critical care setting. This is a prospective observational study conducted in the Department of Medicine in a tertiary care center from Jammu and Kashmir, India, from June 2010 to June 2012. Patients admitted with hypercalcemia were assessed for AKI and evaluated and treated for hypercalcemia. Renal function was monitored during hospitalization and at 1 month of discharge. AKI and hypercalcemia were arbitrarily defined as serum creatinine > 1.5 mg/dl and corrected serum calcium of ≥ 11.5 mg/dl (as per reference hospital lab), respectively.

Results
Thirty patients are included. Hyperparathyroidism and multiple myeloma accounted for 13(43.3%) and 10 (33.3%) cases, respectively. Mean ±SD corrected serum calcium at diagnosis and after treatment at 1 month was 13.56 ± 1.86 mg/dl and 9.49±1.35 mg/dl, respectively; p < 0.001. Mean ±SD serum creatinine at baseline and after treatment of hypercalcemia was 2.87 ±1.68 mg/dl and 1.49±1.34 mg/dl, respectively; p < 0.001. Twenty-three (76.7%) patients had AKI. AKI recovered after treating hypercalcemia in 25 (83.3 %) patients. Mean ± SD days taken for the decrease in serum creatinine to ≤ 1.5 mg/dl was 8.28 ± 4.17 days. Mean ± SD serum creatinine after treatment of hypercalcemia in hyperparathyroidism group versus non-parathyroid group was 0.97 ± 0.35 mg/dl and 1.88 ±1.67 mg/dl, respectively; p value 0.009.

Conclusions
Hypercalcemia is commonly associated with AKI. Primary hyperparathyroidism and multiple myeloma account for the majority of the cases. Hypercalcemic AKI with primary hyperparathyroidism is less common and the outcome is better, as compared to non-hyperparathyroidism-related causes. AKI is reversible in most cases.