Comparative study of children with calciopaenic and phosphopaenic rickets seen at Chris Hani Baragwanath Hospital
Keywords:rickets, calciopaenic, phosphopaenic, Thacher score, Johannesburg, X-linked hypophosphataemic rickets, vitamin D deficiency
INTRODUCTION: The majority of causes of rickets can be divided into two large pathogenic groups, namely calciopaenic and phosphopaenic. Few studies have compared the clinical and biochemical presentations of the two forms of rickets. The aim of this study was to compare the demographic, clinical and biochemical presentations and response to therapy of children with calciopaenic and phosphopaenic rickets.
METHODOLOGY: The study is a retrospective chart review of children diagnosed with rickets at Chris Hani Baragwanath Academic Hospital (CHBAH) in Johannesburg, South Africa, between 2006 and 2012. The radiological response to therapy was evaluated using the Thacher scoring system to assess the severity of rickets.
RESULTS: The study comprises 112 patients from 2 months to 18 years of age diagnosed with rickets (53% with calciopaenic rickets and 47%with phosphopaenic rickets). The calciopaenic group was younger than the phosphopaenic group (20 [7-26] vs 36 [24-51] months; p<0.001), but the phosphopaenic group was more severely stunted than the calciopaenic group at presentation (HAZ scores -3.3 [-4.5 to -2.1] vs -2 [-3.4 to 0.7]; p<0.001. Following treatment, 75% of patients in the calciopaenic group had biomarkers that had normalised completely within a median of 13 (9-18) weeks while only 10% in the phosphopaenic group had normalised within a median of 17 (17-50) weeks. Radiological healing in response to treatment was better in the calciopaenic group compared to the phosphopaenic group (67.5% vs 18%; p-value <0.01).
CONCLUSION: Calciopaenic rickets (mainly vitamin D deficiency) presented at a younger age and response to therapy was better compared to phosphopaenic rickets (mainly X-linked hypophosphataemic rickets). This study highlights the significant differences between calciopaenic and phosphopaenic rickets, which may be helpful to attending orthopaedic surgeons and paediatricians in differentiating between these two groups of rickets and in the management thereof.
SUMMARY OF ABSTRACT: This study highlights the differences between calciopaenic and phosphopaenic rickets, which may be of assistance to attending orthopaedic surgeons and paediatricians in the management of rickets. The study shows that in children with calciopaenic rickets, the majority are vitamin D deficient, and present at a younger age with craniotabes and less severe lower limb deformities compared to children with phosphopaenic rickets who mainly have X-linked hypophosphataemic rickets and are severely short in stature and have genu valgum deformities. The medical management of the two types of rickets differs and response to medical therapy is better in the calciopaenic compared to the phosphopaenic group.