Summary

Hypercalcaemia is an emergency with severe consequences. Dehydration can be an uncommon cause of hypercalcaemia, as seen in this case. A 63-year-old woman with type 2 diabetes mellitus, hypothyroidism and osteoporosis, was admitted to the emergency room with abdominal distension and vomiting for 24 h. Initial evaluation was Hg 18.5 g/dL, Htc 56.2%, creatinine 2 mg/dL, metabolic acidaemia, lactate 8.3 mmol/L, anion gap 19, total Ca²⁺ 17.7 mg/dL and PO₄+ 6.6 mg/dL. CT revealed colonic distension without obstruction or ischaemia. Renal replacement therapy and pamidronate were initiated. The patient's clinical condition deteriorated with septic shock in the context of toxic megacolon and she underwent an emergency subtotal colectomy (10 kg). Hypercalcaemia was corrected in 24 h with aggressive fluid replacement (8 L NaCl 0.9% first 12 h), with a reduction of total Ca²⁺ to 8.2 mg/dL. Other causes of hypercalcaemia were excluded. ‘Hypercalcaemic crisis’ secondary to severe acute dehydration is not mentioned in the literature.