Severe hypercalcaemia of primary hyperparathyroidism: Could giant adenoma be the real culprit rather than carcinoma?

INTRODUCTION Hypercalcaemic crisis is a rare manifestation of hyperparathyroidism and occurs in 1.6-6% of patients with primary hyperparathyroidism (pHPT). Although such high serum calcium levels (>14mg/dl) are attributed to malignancy, it is also associated with benign disease of the parathyroid glands. The aim of this study was to evaluate the clinical features and treatment modalities of patients with severe hypercalcaemia who underwent surgery for pHPT. METHODS The medical records of 537 patients who underwent parathyroidectomy in our department for pHPT between 2005 and 2019 were reviewed retrospectively. Twenty-four (4.4%) of the patients were described as having severe hypercalcaemia. RESULTS Among 24 patients, 71% were female and the mean age was 55.7 years (range: 40-71 years). The mean serum calcium level at time of diagnosis was 15.9mg/dl (range: 14-22.7mg/dl). According to postoperative pathology reports, solitary adenoma, parathyroid cancer and parathyromatosis were diagnosed with the rates of 87.5%, 8.3% and 4.1% respectively. The mean weight of the solitary parathyroid lesions was 14.9g (standard deviation: 8.9g, range: 4-38g). The mean longest diameter was 2.87cm (standard deviation: 1.4cm, range: 1-5.5cm). Serum calcium levels were within the normal range on the first postoperative day in 75% of the cases. CONCLUSIONS Severe hypercalcaemia is a rare but urgent condition of pHPT and requires prompt management. Accelerated surgery after adequate medical treatment should be performed. It is important to emphasise that giant adenoma, which is a benign disease, may be a more common cause of severe hypercalcaemia than carcinoma, unlike previously thought.