Primary hyperparathyroidism presenting as atraumatic bilateral hip fractures: a case report

Primary hyperparathyroidism (PHPT) affects up to 1.5% of older adults, causes bone loss at cortical sites and increases fracture risk. However, atraumatic hip fractures due to PHPT are rare. We report the case of an older female diagnosed with PHPT after presenting with atraumatic bilateral neck of femur fractures.

An 82-year-old white woman was referred to the emergency department with progressive left hip pain over two months and was unable to bear weight on presentation. There was no history of trauma, falls, prior fracture or diagnosis of osteoporosis. X-ray of hips showed a displaced left neck of femur fracture and a non-displaced healing right neck of femur fracture. Pelvic computed tomography (CT) confirmed X-ray findings and showed callus formation suggesting subacute fractures with no evidence of destructive lesions. Blood tests revealed hypercalcemia (calcium 2.76 mmol/l), normal renal profile and serum electrophoresis, vitamin D deficiency [25(OH)D of 12 nmol/l] and an elevated parathyroid hormone (PTH) of 172 pg/ml. There was no evidence of malignancy on femoral biopsies. Densitometry (DXA) revealed T-scores of - 4.0 (0.607 g/cm²) at lumbar spine and - 4.9 (0.401 g/cm²) at distal forearm. Neck imaging did not identify a parathyroid adenoma, and her hyperparathyroidism was managed non-surgically. She was treated with zoledronic acid for osteoporosis, with subsequent lifelong denosumab planned.

This case highlights the impact of undiagnosed PHPT on bone loss and the rare possibility of atraumatic hip fractures. It also emphasizes the value of DXA screening and investigation for secondary causes of osteoporosis in older adults.