Calcium levels on admission and before discharge are associated with mortality risk in hospitalized patients

Investigate the association of calcium levels on admission and change in levels during hospitalization with hospitalization outcomes.

Historical prospective data of patients hospitalized to units of internal medicine between 2011 and 2013. Albumin-corrected-calcium levels were classified to marked hypocalcemia (<7.5 mg/dL), mild hypocalcemia (7.5–8.5 mg/dL), normal calcium (8.5–10.5 mg/dL), mild hypercalcemia (10.5–11.5 mg/dL), marked hypercalcemia (>11.5 mg/dL). Main outcomes were length-of-hospitalization, in-hospital and long-term mortality.

Cohort included 30,813 patients (mean age 67 ± 18 years, 51% male). Follow-up (median ± standard deviation) was 1668 ± 325 days. Most patients had normal calcium on admission (93%), 3% had hypocalcemia, 3% had hypercalcemia. Common causes for marked hypercalcemia were malignancy (56%) and hyperparathyroidism (22%). Last calcium levels before discharge or death were normal in 94%, with similar rates of hypercalcemia or hypocalcemia (3% each). Compared to in-hospital mortality with normal calcium on admission (6%), mortality was higher with mild (8%) and marked hypocalcemia (11%), and highest with mild (18%) and marked hypercalcemia (22%). Mortality rate at the end of follow-up was 48% with normal calcium or mild hypocalcemia, 51% with marked hypocalcemia, 68 and 79% with mild and marked hypercalcemia, respectively. Patients with normal calcium on admission and before discharge had the best prognosis. Hypercalcemia on admission or before discharge was associated with a 70% mortality risk at the end of follow-up. Normalization of admission hypercalcemia had no effect on long-term mortality risk.

Abnormal calcium on admission is associated with increased short-term and long-term mortality. The excess mortality risk is higher with hypercalcemia than hypocalcemia. Calcium normalization before discharge had no effect on mortality.