Rickets in the New Age of Food Allergies: A Case Report and Comprehensive Review.

Introduction: Rickets is a disorder of defective bone mineralization resulting in skeletal deformities, growth retardation, and increased risk of fractures. Nutritional rickets, once a historical disease, has reemerged in select pediatric populations despite modern food fortification efforts. Many of the most common food allergens - dairy, eggs, and fish - are primary dietary sources of vitamin D, which presents a unique risk factor for development of rickets. Children with multiple food allergies are at a heightened risk, particularly if their diets are not adequately supplemented.

Case report: This case report describes a 2-year-old male with multiple food allergies who developed vitamin D-deficient rickets. He was referred to a pediatric orthopedic surgeon by his primary care physician due to concerns about progressive bilateral bowing of his legs. Radiographic evaluation of the lower extremities revealed characteristic findings consistent with nutritional rickets, including irregular cupping, fraying, and flaring of the metaphyses at the distal femur, tibia, and fibula bilaterally. Laboratory testing confirmed a biochemical profile consistent with severe vitamin D deficiency and impaired bone mineralization. The patient's serum calcium level was 9.0 mg/dL and serum phosphorus level was 2.9 mg/dL. Alkaline phosphatase level was markedly elevated at 1060 U/L and serum 25-hydroxyvitamin D level was critically low at 4 ng/mL. Treatment was initiated with high-dose vitamin D supplementation at 6000 IU of cholecalciferol daily. Additionally, dietary counseling was emphasized, and follow-up was arranged with pediatric endocrinology, a metabolic specialist, and orthopedic follow-up is ongoing to evaluate for correction or progression of the bowing.

Conclusion: This case highlights the intersection of pediatric metabolic bone disease and food allergies, emphasizing the need for heightened awareness of nutritional deficiencies in children with restricted diets. Despite public health advances, vitamin D-deficient rickets continues to emerge in select populations, underscoring the necessity for early diagnosis, supplementation, and interdisciplinary management.