M K TIONG1,2, C J YATES1,2, N D TOUSSAINT1,2, A MURUGASU1
1The Royal Melbourne Hospital, Parkville, Australia, 2University of Melbourne, Parkville, Australia
Background: Recent international guidelines have suggested that management of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) not on dialysis move away from the use of active vitamin D, due to risk of hypercalcaemia. This has led to a more conservative approach, particularly in patients with moderate but stable hyperparathyroidism.
Case report: A 28-year-old male with slowly progressive CKD from hereditary methylmalonic acidaemia presented with a mandibular bone mass. Imaging demonstrated a lytic lesion in the body of the mandible. Serum biochemistry showed stable moderate SHPT with a parathyroid hormone (PTH) level of 75.6pmol/L (RR 1.7-10pmol/L). Surgical enucleation of the lesion was performed and histopathology demonstrated the presence of osteoclast-type giant cells consistent with a Brown tumour (given underlying SHPT). Mineral and bone abnormalities in patients with advanced CKD are almost universal, although development of Brown tumours is uncommon and usually only seen in those with end-stage kidney disease requiring dialysis with significant disturbances of mineral and bone metabolism over many years. Our patient’s presentation is unusual with the development of a Brown tumour despite pre-dialysis CKD with relatively stable PTH. Observational studies consistently suggest an association between SHPT and increased morbidity and mortality. While medical therapies have traditionally been used to suppress PTH, clinical studies have failed to demonstrate improvement in patient-centred outcomes and instead concerns have been raised about active vitamin D therapy and risk of hypercalcaemia. This creates a challenging situation for patients who may experience bone complications despite relatively modest SHPT.
Conclusion: This case highlights the need to individualise treatment targets while further research is undertaken to develop better markers of mineral and bone disturbances in CKD.
Dr Mark Tiong completed his RACP fellowship in nephrology in 2019 and is currently undertaking his PhD in the area of CKD-MBD at The Royal Melbourne Hospital and The University of Melbourne. He is also interested in Aboriginal and Torres Strait Islander health, having previously worked for the Central Australian Health Service in Alice Springs, and is also a current member of the ANZDATA Aboriginal and Torres Strait Islander Health Working Group.