SUN-496 A Perioperative Risk For Exacerbation of Hypercalcemia in Primary Hyperparathyroidism

[Introduction] Primary hyperparathyroidism (PHPT) occasionally presents a hyperparathyroid crisis which provides a pivotal cue for its diagnosis. However, the perioperative risk for exacerbation of hypercalcemia has been unknown in PHPT. We herein report 2 cases of PHPT which presented a hyperparathyroid crisis during the perioperative period for other complications. [Case presentaion] Case 1; A 81-year-old man was referred to our center due to urinary stone and hypercalcemia. Baseline laboratory data were as follows; corrected serum Ca 11.2 mg/dl; serum P 2.0 mg/dl; whole PTH 89.6 pg/ml, eGFR 49 ml/min/1.73m(2). CT revealed a neck tumor of 10 mm with 99mTc-MIBI uptake, which was considered as a cause of PHPT. Simultaneously, CT also pointed out thoracic aortic aneurysm of 70 mm. Therefore, he underwent endovascular stent graft therapy prior to tumorectomy of PHPT. The procedure of stent graft was successfully performed but also caused subarachnoid hemorrhage and acute kidney injury (AKI). Corrected Ca level was subsequently elevated to 12.4 mg/dl, implying an exacerbation of PHPT. He received 60 mg denosumab administration in order to control Ca level complicated with AKI, resulted in improvement of hypercalcemia. However, PTH level was not significantly changed (57.4 pg/ml) during the period, indicated that lower urinary excretion of calcium due to AKI was the main cause of Ca level elevation. Case 2; A 57-year-old woman was admitted to our center due to incidental hypercalcemia. Baseline laboratory data were as follows; corrected serum Ca 12.5 mg/dl; serum P 2.1 mg/dl; whole PTH 140 pg/ml, eGFR 74 ml/min/1.73m(2). CT revealed a neck tumor of 17 mm with 99mTc-MIBI uptake, considered as a cause of PHPT. Unexpectedly, MR imaging revealed meningioma of 48 mm on the Turkish saddle. She underwent embolization and removal of meningioma prior to tumorectomy of PHPT. After surgery, she had a persistent disturbance of consciousness because of hypernatremia (over 160 mM) and hypercalcemia (17.2 mg/dl) complicated with AKI. As a hyperparathyroid crisis, we administered 60 mg denosumab and continued fluid replacement therapy, leading to gradual improvement of electrolyte imbalances. PTH level was significantly elevated to 443 pg/ml compatible with a hyperparathyroid crisis. Her serum Ca level was kept lower than 12 mg/dl by denosumab for more than 3 months. [Conclusion] Our cases suggested that serum Ca level in PHPT could be influenced by perioperative conditions, although the trigger for exacerbation of PHPT remains unclear. Management of PHPT should be considered before surgery for other complications. Denosumab is useful for management of PHPT regardless of renal function.