Aim: Investigate the association of calcium levels on admission and change in levels during hospitalization with hospitalization outcomes.
Methods: 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.
Results: 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.
Conclusions: 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.