Long-term complications of systemic oxalosis in children—a retrospective single-center cohort study

Background Systemic oxalosis is a severe complication seen in primary hyperoxaluria type I patients with kidney failure. Deposition of insoluble calcium oxalate crystals in multiple organs leads to significant morbidity and mortality. Methods We describe a retrospective cohort of 11 patients with systemic oxalosis treated at our dialysis unit from 1982 to 1998 (group 1) and 2007–2019 (group 2). Clinical and demographic data were collected from medical records. Imaging studies were only available for patients in group 2 ( n = 5). Results Median age at dialysis initiation was 6.1 months (IQR 4–21.6), 64% were male. Dialysis modality was mostly peritoneal dialysis in group 1 and daily hemodialysis in group 2. Bone disease was the first manifestation of systemic oxalosis, starting with the appearance of sclerotic bands (mean 166 days, range 1–235), followed by pathological fractures in long bones (mean 200.4 days, range 173–235 days). Advanced disease was characterized by vertebral fractures with resulting kyphosis, worsening splenomegaly, and adynamic bone disease. Two patients developed pulmonary hypertension, 4 and 8 months prior to their death. Four of 11 patients developed hypothyroidism 0–60 months after dialysis initiation. Only one patient survived after a successful liver–kidney transplantation. Four patients died after liver or liver–kidney transplantation. Conclusions This is the first comprehensive description of the natural history of pediatric systemic oxalosis. We hope that our findings will provide basis for a quantitative severity score in future, larger studies. Graphical abstract