6859 Recurrent Hypercalcemia Due to Prolonged Immobilization After a Profound Vascular Event

Disclosure: J.L. Azocar Villalobos: None. B. Godasi: None. T. Duro: None. C. Lovato: None. Background: Hypercalcemia from immobility is rare, typically seen in young men with spinal cord injuries, but it has also been reported in elderly patients with co-morbidities after sustaining a vascular event. The condition is characterized by increased bone resorption after skeletal unloading, which leads to hypercalcemia and decreased levels of parathyroid hormone and 1,25(OH)2 vitamin D. This, in turn, results in decreased bone formation and a significant renal calcium leak. Clinical Case: A 56-year-old woman with a history of cirrhosis due to alcohol abuse and hypertension was admitted after sustaining a left middle cerebral artery infarction, which was complicated by cerebral edema with brain compression and herniation that resulted in profound neurologic deficits. The patient underwent craniotomy, subdural evacuation, and partial temporal lobectomy. During the course of her hospitalization, she developed recurrent episodes of hypercalcemia. The first episode occurred about 6 weeks after her admission. Serum calcium, corrected for albumin, was as high as 16.2 mg/dL (n 8.4-10.4 mg/dL) and PTH <6 pg/mL (n 18-84 pg/mL). The patient was given IV fluids and calcitonin subcutaneously for 48 hours. She also required continuous renal replacement therapy for 3 days due to oliguria. Another episode occurred 2 months later and was managed with IV fluids, calcitonin for 48 hours, and 4 mg IV zoledronic acid. The patient developed hypercalcemia again 4 months later, which required another dose of 4 mg IV zoledronic acid and IV fluids. The patient remained normocalcemic for the following 3 months until she was transferred to a long-term care facility. Additional workup excluded other causes, including hypercalcemia of malignancy with PTHrp <2.0, normal calcitriol, SPEP, UPEP and kappa lambda ratio, and negative CT scans. The diagnosis of hypercalcemia due to immobilization was confirmed by her history. Supporting lab work revealed marked bone resorption with a c-telopeptide 3,277 pg/mL (n 177-1015 pg/mL postmenopausal female). Bone-specific alkaline phosphatase was 22.6 ug/L (7.0-22.4 ug/L postmenopausal female). Clinical Lessons: The diagnosis of hypercalcemia due to immobilization should include patient history, supporting lab work, and must exclude other causes. Skeletal loading is the preferred treatment. However, as this case illustrates, other treatment modalities must be pursued if skeletal loading is not feasible and there is persistent hypercalcemia. Presentation: 6/2/2024