Hypercalcemia in hospitalized patients: prevalence, etiology and mortality predictors in a tertiary internal medicine ward

INTRODUCTION: Hypercalcemia is a potentially life-threatening electrolyte disorder with diverse etiologies and clinical manifestations, frequently encountered in hospitalized patients. Understanding its prevalence, causes, and associated outcomes in the inpatient setting is crucial for improving patient management and prognosis. The objectives were to determine the prevalence, etiological distribution, clinical and demographic characteristics, comorbidities, laboratory features, and mortality risk factors of hypercalcemia among patients admitted to an internal medicine clinic in a tertiary university hospital. MATERIAL AND METHODS: This retrospective, observational cohort study included adults (≥ 18 years) hospitalized with hypercalcemia (corrected calcium ≥ 10.2 mg/dL, confirmed twice at least 24 hours apart) between January 2022 and January 2024. Hypercalcemia severity was classified as mild, moderate, or severe. Etiological categories included malignancy-associated, endocrine-related, vitamin D-mediated, other, and undetermined. Demographics, comorbidities, laboratory parameters, treatments, and outcomes were recorded. Univariate and multivariate analyses were performed to identify mortality risk factors. RESULTS: Among 3,157 admissions, 190 patients (prevalence 6%) had confirmed persistent hypercalcemia (mean age 72.3 ± 13.1 years; 61.6% female). Malignancy was the leading cause (49.5%), followed by other causes (24.7%), undetermined (15.8%), endocrine (8.4%), and vitamin D-mediated (1.6%). Severe hypercalcemia (11.6%) was predominantly associated with malignancy. Overall in-hospital mortality was 24.2%, with male sex, malignancy, solid tumors, elevated aspartate aminotransferase (AST), hypoalbuminemia, and age 65-80 years independently associated with mortality. Survival was significantly worse in malignancy-related cases. The optimal parathyroid hormone (PTH) threshold for predicting malignancy was identified as ≤ 12.61 pg/mL. This cut-off demonstrated a sensitivity of 71.4% and a specificity of 91.3%. CONCLUSIONS: Hypercalcemia in hospitalized patients is predominantly associated with malignancy and advanced age, and is linked with high mortality. Early identification of risk factors and etiology-driven management are critical for improving outcomes.