Elaine Cheng1, Akshay Athavale1,2, Kenneth Lee2,3, Angus Ritchie1,3
1Department of Renal Medicine, Concord Repatriation General Hospital, Sydney, Australia, 2Concord Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia, 3NSW Health Pathology, Concord Repatriation General Hospital, Anatomical Pathology, Sydney , Australia
Background
Chronic kidney disease – mineral and bone disorder is a well-recognised complication of advanced chronic kidney disease (CKD). This manifests as a spectrum of disease, with osteitis fibrosa being a consequence of high-turnover bone disease, and osteomalacia as a result of low—turnover bone disease. We report a case of biopsy-proven osteomalacia following denosumab administration in a patient with known osteitis fibrosa.
Case Report
A 43 year old male with end stage kidney disease on maintenance intermittent haemodialysis was referred for investigation following multiple atraumatic fractures. Background history was significant for Fabry’s disease and tertiary hyperparathyroidism without parathyroidectomy.
Initial investigations demonstrated corrected calcium of 2.24mmol/L, phosphate 1.25mmol/L, parathyroid hormone 86.7pmol/L, 1,25 OH-vitamin D 110pmol/L, bone-specific alkaline phosphatase 53.7ug/L, procollagen type 1 n-terminal peptide 2219ug/L and c-terminal collagen type 1 telopeptide >6000ng/L.
Skeletal scintigraphy demonstrated exquisite uptake throughout the axial skeleton and peripheral joints, with patchy sclerosis throughout the pelvis and end plate sclerosis of the lumbar spine.
Double tetracycline labelled bone biopsy was performed five weeks after 60 mg denosumab was administered for fracture prevention. Bone biopsy was compared with bone histopathology from both hips from previous fracture repairs. Earlier histopathology demonstrated increased osteoblastic and osteoclastic activity with peritrabecular fibrosis consistent with osteitis fibrosa. Following denosumab, biopsy showed complete absence of osteoclastic activity, with markedly thickened osteoid and decreased mineral bone consistent with severe osteomalacia.
Conclusion
We present a case of iatrogenic osteomalacia following the administration of denosumab in a patient with atraumatic fracture history and osteitis fibrosa. The use of antiresorptives in patients with osteoporosis and advanced CKD should be considered carefully, as it may induce pathologic low-turnover bone disease without reducing fracture risk.
Biography:
Elaine Cheng is a currently a basic physician trainee at Concord Repatriation General Hospital.