Endocrine Abstracts

Objective: A young woman presented with marked hyperparathyroidism with post-operative course complicated by hungry bone syndrome and diagnostic and management challenges of ongoing hypocalcaemia with hyperparathyroidism.

Method: ML, a 32-year-old Fijian Indian female, was referred with severe hypercalcaemia, following one-year history of migratory debilitating bone pain. Initial labs showed corrected calcium (C.Ca) 3.17 [2.10–2.60 mmol/l], parathyroid hormone (PTH) 305.4 [2.0–6.0 pmol/l] and 25-hydroxyvitamin D (25-VitD) of 22 [40–80 nmol/l]. Acute management included admission for intravenous fluids and bisphosphonates, which normalised C.Ca. A parathyroid SESTAMIBI/CT-SPECT demonstrated a 31×9×33 mm soft tissue mass in anterior superior mediastinum with focal uptake at T3. Further CT neck demonstrated 10×5×5 mm mass between left common carotid and subclavian arteries.

Results: ML’s surgical resection of the mediastinal mass was immediately complicated by generalised bony pain, pleural effusions and despite aggressive replacement of calcium, marked hypocalcaemia (Day 1 C.Ca 1.99); consistent with an exaggerated ‘hungry bone syndrome’. ML has been followed closely for on-going optimisation of calcium and vitamin D; three-month labs showed elevated PTH (30.7 pmol/l), despite normalisation of 25-VitD (79 nmol/l) and improved C.Ca (2.04 mmol/l). Her pre-operative DEXA scan showed T-scores: lumbar spine −5.1SD and bilateral femoral necks −5.6SD. A MRI cervical spine demonstrated widespread lytic lesions including, a lesion in the C2 spinous process and posterior pedicles, considered consistent with pathological fracture. Histopathology reported a 70×65×51 mm; 41 gm mass with no invasive features. Parafibromin was positive, whilst PGP9.5 was negative; other patterns of staining were normal, making HRPT2/CDC73 mutation unlikely.

Conclusion: This case highlights: 1) the diagnostic challenge of marked hyperparathyroidism with a clinical picture suggestive of malignancy, but histological evidence not supporting invasion; 2) the management issues of moderating post-operative severe hypocalcaemia and hungry bone phenomenon; and 3) the on-going diagnostic and management of post-operative hyperparathyroidism with hypocalcaemia. In summary, atypical primary hyperparathyroidism presents unique diagnostic and management challenges.