Rachitic changes, demineralization, and fracture risk in healthy infants and toddlers with vitamin D deficiency

Abstract

Purpose: To examine radiographic findings in children with vitamin D deficiency in comparison with biochemical marker levels and prevalence of fractures.

Materials and methods: The parents or guardians of all participants provided written informed consent at the time of enrollment. The institutional review board approved the protocol, and HIPAA guidelines were followed. From a prospective sample of children seen for routine clinical care, 40 children with vitamin D deficiency (25-hydroxyvitamin D [25-OHD] level, ≤ 20 ng/mL) were identified, and high-detail computed radiographs of the wrists and knees were obtained. The children ranged in age from 8 to 24 months. Radiographs were scored by three readers with use of the 10-point Thacher score for rachitic changes and a five-point scale for demineralization. Serum calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels were determined. Fracture history was obtained for 35 of the 40 patients (88%).

Results: All readers identified rachitic changes at both readings in two patients (5%) and demineralization in two patients (5%). Interrater agreement was 65% for rachitic changes (κ = 0.33) and 70% for demineralization (κ = 0.37). When the majority of the raters determined that rachitic changes were absent at both readings, alkaline phosphatase levels were lower than those with other assessments (median, 267 vs 515 U/L [4.4589 vs 8.6005 μkat/L]; P = .01). When most raters determined that demineralization was present at both readings, serum 25-OHD levels were lower than those at other assessments (median, 9.0 vs 17.5 ng/mL [22.464 vs 43.68 nmol/L]; P = .02). No fractures were reported or identified radiographically.

Conclusion: In infants and toddlers with vitamin D deficiency, rachitic changes and definite demineralization are uncommon and fracture risk is low.

Anteroposterior computed radiographs of the knee in the two patients with rachitic changes seen by all readers. A, Image of right knee in a 10-month-old child shows partial lucency of the zone of provisional calcification (arrow). The metaphyseal margin in the medial distal femoral metaphysis is intact. The average Thacher score was 1.6 (range, 0.5–2.0), there was mild demineralization, and the 25-OHD level was 11 ng/mL (27.456 nmol/L). B, Image of left knee in an 11-month-old child shows partial lucency of the zone of provisional calcification (arrows) and loss of the metaphyseal margin in the medial and lateral distal femoral metaphysis and the lateral proximal tibia metaphysis. No metaphyseal fragmentation is evident. The average Thacher score was 5.1 (range, 2–7), there was questionable demineralization, and the 25-OHD level was 7 ng/mL (17.472 nmol/L).