Endocrine Abstracts

Case history: A 43-year-old Syrian woman presented with severe right thigh pain following a fall from standing height. Progressive hip and back pain in the preceding 18 months resulted in her mobilizing with crutches. Past medical history included a reported bony tumour resected from her wrist three years earlier, clavicle fracture and previous renal calculi. She took no regular medications.

Investigations: Pelvic radiograph showed a right proximal femoral shaft fracture, with appearances of a surrounding lytic lesion. CT body demonstrated a 10 cm pelvic soft tissue mass centered around the right ileum extending towards the acetabulum, soft tissue deposits in the pubic rami bilaterally and left iliac crest, and sclerotic and lytic areas in the sternum. Serum adjusted calcium was elevated 2.74 mmol/l (2.15–2.5), and rose to a peak of 3.0 mmol/l during her admission. The working diagnosis was malignancy with pathological fracture. PTH was unexpectedly elevated 88.4 pmol/l (1.6–6.9), 25-hydroxyvitamin D <8 nmol/l (50–120), creatinine 37 mmol/l (45–90) and eGFR>60 ml/min/1.73 m2. Histology from a CT guided biopsy of the iliac lesion showed a benign primary bone lesion with presence of osteoclast-like giant cells, suggestive of osteitis fibrosa cystica (Brown’s tumour). Parathyroid ultrasound and MIBI scan confirmed a left inferior parathyroid adenoma. The diagnosis of primary hyperparathyroidism with secondary osteitis fibrosa cystica was made.

Results and treatment: She underwent fixation of the fracture under the orthopaedic team, followed by a left inferior parathyroidectomy. Intraoperatively, PTH fell from 36.4 pmol/l to 4.5 pmol/l and histology revealed an enlarged parathyroid (4×1.5×1 cm) with no atypia. Pre-operatively she was hydrated and given vitamin D replacement. She developed hypocalcaemia (adjusted calcium 2.10 mmol/l) six days post-operatively, at which point started oral calcium replacement. She underwent rehabilitation and was subsequently discharged with a normal calcium.

Conclusions and points for discussion: This case demonstrates the consequences of unregulated osteoclast activity secondary to untreated hyperparathyroidism. The considerably elevated PTH was likely attributable to both primary hyperparathyroidism due to parathyroid adenoma, and secondary hyperparathyroidism due to longstanding vitamin D deficiency. Early diagnosis and treatment of hyperparathyroidism can prevent the development of osteitis fibrosa cystica and subsequent fractures, which carry morbidity and mortality consequences and an opportunity was likely missed several years earlier in this case. Furthermore, adequate vitamin D replacement pre-operatively is essential to prevent hungry bone syndrome post-operatively, particularly in patients with extensive bony involvement. Finally, although the operative and histological findings were not suggestive of a parathyroid carcinoma, ongoing careful clinical follow up is paramount.