Endocrine Abstracts

Introduction: Tertiary hyperparathyroidism (tHPT) develops when the parathyroid gland becomes autonomous in hormone secretion, usually after prolonged secondary hyperparathyroidism. "Brown tumours" (BT) and postoperatively “hungry bone syndrome” (HBS) are rare complications of HPT occurring in up to 1.5% in tHPT and around 13% in primary HPT, respectively.

Case presentation: A 49-year-old female patient was referred to an endocrinologist due to hypercalcemia. Among clinical findings, the patient is obese and has cutaneous calcifications. Examinations started 2 years before, because of gradually increasing bone pain. She was then diagnosed with chronic kidney disease (stage IV/V) and dilated cardiomyopathy. There was clinical suspicion of multiple myeloma or metastatic disease. CT scan showed osteolytic lesions in both scapula, IV-IX ribs, VIII and IX vertebrae, pelvic bones and femur. During the evaluation, we found hypercalcemia (corrected calcium 2.5-2.85 mmol/l) with hypocalciuria, hypovitaminosis D, elevated alkaline phosphatase, hyperparathyroidism (PTH 1160-1267 ng/l) and high bone turnover markers. Osteodensitometry showed osteoporosis. Neck ultrasound revealed a hypoechogenic mass left paratracheal measuring 10 x 23 mm, and MIBI scintigraphy confirmed hyperactive left inferior parathyroid. A total parathyroidectomy was performed, revealing a left inferior parathyroid adenoma. Postoperatively PTH was 58-80 ng/l, and profound hypocalcemia (corrected calcium 1.4-1.8 mmol/l) was observed. Continuous intravenous calcium gluconate therapy alone lasted for 2 weeks, following high-dose of oral calcium carbonate (up to 16 g/24h) and calcitriol (up to 3 mg/24h) in combination with calcium gluconate intermittent boluses. She was discharged with 12 g/24h calcium carbonate and 2 mg/24h calcitriol, and with careful control of biochemics, the dose was reduced.

Conclusion: BT should be suspected in patients with chronic kidney disease complicated with tHPT, as it can easily be mimicked by multiple myeloma and tumour metastasis (our patient’s case raised clinical doubt between primary HPT and tHPT). HBS should be kept in mind postoperatively, especially in patients with generalized BT and longstanding HPT.