Potential etiological spectrum and burden of rickets in hospitalized children: a retrospective study from Children’s Hospital 2

Vitamin D-dependent rickets (VDDR) is a rare etiology of rickets and is frequently underrecognized in clinical practice. Our aim is to delineate the etiological spectrum of rickets, focusing on VDDR and its height characteristics among inpatients at Children’s Hospital 2. Twenty-seven cases were identified based on abnormal bone radiographs, elevated levels of alkaline phosphatase (ALP) and hypocalcemia, hypophosphatemia or bone deformities. Response to calcitriol therapy was assessed to distinguish probable VDDR-I and probable VDDR-II. Clinical characteristics, laboratory findings and treatment were retrospectively recorded. VDDR was suspected in 63% of cases, with the median time to diagnosis of 0.5 months (range: 0.5–18 months). More severe stunting was observed among probable VDDR patients (height-for-age: –4.18±1.81 SD) than among vitamin D-deficient rickets (VDD) patients (height-for-age: –2.23±1.76 SD) (mean difference: –1.95; 95% confidence interval [CI]: –3.54 to –0.36). Probable VDDR-I patients exhibited prolonged calcium recovery (16.2 vs. 4.1 days; mean difference: 14.1; 95% CI: 10.6 to 17.6) and seizure resolution times (13.5 vs. 1.5 days; mean difference: 11; 95% CI: 9 to 44). Our study recorded a high proportion of suspected VDDR cases. More severe stunting was observed in probable VDDR patients. These observations might be influenced by the exclusion of outpatients and less severe cases, as well as potential limitations in etiological classification, and therefore should not be generalized for the rickets population.