Hypercalcaemia can be caused by many different diseases. This article summarizes the causes, pathophysiologic mechanisms and diagnostic procedures as well as treatment recommendations. The main focus is on hypercalcaemia in primary hyperparathyroidism (PH), complemented by a case report. An elevated total calcium level should generally be investigated and verified by measurement of ionized calcium concentration. The further diagnostic approach depends on the phosphate level. Tumour screening, measurement of parathormone and parathromone-related protein and sonography of parathyroid glands may be necessary. If the calcium-phosphate-product exceeds 60 mg/dl, there is a risk of tissue mineralisation and a rapid treatment of hypercalcaemia is required. For acute therapy, sodium chloride infusion, furosemide and glucocorticoids can be used. Glucocorticoids should only be given after strict indication and after a definite diagnosis. For long-term management, bisphosphates, particularly alendronate, are increasingly used successfully. Causal therapy of PH can be performed by parathyreoidectomy, heat ablation or ethanol ablation. Thereafter, particularly in cases of severe preoperative hypercalcaemia, hypocalcaemia can occur. Treatment is performed using vitamin D3 (calcitriol), which may also be given preoperatively in cases of severe hypercalcaemia. A concomitant oral calcium supplementation using calcium carbonate as medication of choice is contentious. Due to a potential relapse after successful excision of the affected parathyroid gland in PH, the serum calcium level should be monitored periodically.
Keywords: Calcium; PTH; canine; parathormone; parathyroid gland.