Endocrine Abstracts

Background Fibrocystic osteitis is rare PHPT manifestation. Poor management and delay in diagnosis of fibrocystic osteitis may lead to reduced quality of life and also provoke severe postoperative hypocalcemia – «hungry bone» syndrome.

Clinical case We present a case of 66-years-old Caucasian woman, with history of urulithiasis/nephrocalcinosis (CKD stage 4), two pathological fractures, and fibrocystic osteitis. In Jan 2021 MRI was performed due to increasing bone and joint pain, unsteady gait and showed multiple vertebral lesions in L3 and L4. Since the diagnosis was not established CT was performed, it reveald bone resorption sites in Th12, L2 – L5, sacrum, and left ileum. These changes were considered to be multiple myeloma signs, but bone marrow trephine biopsy and monoclonal antibody assay did not support this diagnosis. L3 trephine biopsy suggested the giant-cell tumor. Zoledronic acid (4 mg/28 days) therapy was started and undertook whithin 4 months. Later PHPT was suspected. Subsequently iPTH level was 2306.9 pg/ml (15.0–68.3), serum Ca⁺⁺ level – 2.17 mmol/l (1.11–1.29), serum total Ca – 3.86 mmol/l (2.15–2.65), 25(OH)D – 10.80 ng/ml (9.40–59.10). Within the adenoma localization neck ultrasound was performed, although it didn’t show any lesions. CT and ¹¹C-methionine PET/CT neck and thorax scans revealed two lesions presumed to be ectopic parathyroid adenomas (3.0x2.1x4.8 cm and 0.8x0.5x0.9 cm). Loop diuretics, rehydration, and cholecalciferol (2000 IU/daily) therapy was started. Parathyroidectomy was performed shortly due to increasing hypercalciemia, both lesions were confirmed to be adenomas. From the third day postoperatively low serum Ca⁺⁺ was detected 0.85 mmol/l in terms of normal iPTH level (45.83 pg/ml), as the patient was having seizures, muscle pain, hallucinations, fatigue, and bradycardia. This condition was evaluated as a «hungry bone» syndrome in terms of prolonged course of fibrocystic osteitis. IV calcium gluconate (16.8 g/daily) and oral calcium carbonate/citrate (5 g/daily), cholecalciferol (4000 IU/daily) and alfacalcidol (4 μg/daily) were used to cope with hypocalcemia. Fourteen-day therapy and replacing alfacalcidol with calcirliol (2 μg/daily) allowed to withdraw IV calcium and reduce oral calcium supplementation.

Conclusion. Delayed diagnosis of long-term hypercalcemia, high iPTH level, unsubstituted 25(OH)D deficiency, and the use of bisphosphonates in high doses caused development of “hungry bones” syndrome in early postoperative period. Severe hypocalcemia required prescription of active and native forms of vitamin D, oral calcium supplements and IV calcium therapy.