Is hypercalcaemia immediately life-threatening? A prospective study

Objective Hypercalcaemia is often considered as an emergency because of a potential risk of life-threatening arrhythmias or coma. However, there is little evidence, apart from case studies, that hypercalcaemia can be immediately life-threatening. The aim of our study was to prospectively assess whether hypercalcaemia (Ca ≥ 3 mmol/L) was associated with immediately life-threatening complications. Design and methods We conducted a prospective observational study aiming to include the first one hundred patients aged ≥18 who had a calcium concentration ≥3 mmol/L, admitted to the emergency department (ED). The primary outcome was the number of life-threatening cardiac arrhythmias (ventricular tachycardia, ventricular fibrillation, sinus arrest and second- or third-degree atrioventricular blocks) or neurological complications defined by a Glasgow Coma Scale score <9 during the stay in the ED. The secondary outcomes were correlation between calcium concentrations and ECG (electrocardiogram) QTc intervals, Glasgow Coma Scale scores and mortality during the following 12-month follow-up period. Results The median calcium concentration was 3.3 mmol/L (3.1–3.7). Cancer was the first cause of hypercalcaemia. No patient presented a life-threatening cardiac arrhythmia during their stay in the ED. Three patients presented a life-threatening neurological complication. There was no correlation between calcaemia and QTc intervals or Glasgow Coma Scale score. Prognosis was poor, and 43 patients died during the 12 months. Conclusions We found no cases of immediately life-threatening cardiac arrhythmias. Three patients had indeed a life-threatening neurological complication but always had at least one other major factor that could severely alter mental status, such as profound metabolic acidosis. Significance statement This paper aims to revisit what most physicians, whether specialists or not, consider to be scientifically proven facts concerning the immediate threat caused by hypercalcaemia. Its novelty is threefold: first, this is the only prospective study that exists to date studying the life-threatening consequences of hypercalcaemia; second, having included one hundred patients, we found no life-threatening cardiac arrhythmias, which is not what would be expected if one reads guidelines concerning hypercalcaemia; and third, life-threatening neurological complications were very rare and only occurred in patients with at least one other major cause of altered neurological status, such as severe metabolic acidosis or hypernatraemia.