The clinical spectrum of adult patients with hypercalcaemia attending a tertiary centre in South Africa

Vollständiger Abstract

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Background: Hypercalcaemia is associated with significant morbidity and mortality. We described the prevalence, causes, biochemical features, management and in-patient outcomes of adult patients with hypercalcaemia at a South African tertiary centre in the Western Cape province. Methods: We conducted a retrospective cohort study of adult hospitalised and outpatients (≥ 18 years) with hypercalcaemia, defined as an unadjusted total serum calcium > 2.50 mmol/L, at Tygerberg Hospital between 01 January 2023 and 31 December 2023. Patients with concurrent parathyroid hormone (PTH) measurements were included in the study. Demographic, clinical, laboratory, treatment and outcome data were extracted from electronic health records (EHR). Hypercalcaemia severity was categorised, and univariate logistic regression was used to identify the predictors of inpatient mortality in this setting. Results: Among 298 559 adult patient encounters, 2432 hypercalcaemic episodes were identified, giving a period prevalence of 0.81%. These episodes occurred in 1531 unique patients, of whom 129 (8.4%) had a PTH concentration measured concurrently with the serum calcium and were therefore eligible for aetiological classification and analysis. The mean age was 55 years, and approximately 75% were female. Primary hyperparathyroidism was the most common cause of hypercalcaemia (54%), followed by malignancy (19%) and chronic kidney disease (12%). Malignancy was associated with the highest total serum calcium concentrations. Overall inpatient mortality was 12%, highest among patients with malignancy (33%). Predictors of inpatient mortality included malignancy, total serum calcium concentration and kidney dysfunction. Conclusion: In this South African cohort, primary hyperparathyroidism (PHPT) and malignancy were the leading causes of hypercalcaemia. Malignancy-associated hypercalcaemia conferred the highest mortality, highlighting the prognostic importance of hypercalcaemia in this group of patients. Contribution: This study provides updated epidemiological data on hypercalcaemia from a South African tertiary centre, addressing a four-decade gap in the local literature. The findings reinforce the importance of concurrent PTH measurement in the diagnostic workup of hypercalcaemia and highlight the prognostic significance of malignancy-associated hypercalcaemia in this setting.