Nutritional rickets in Denmark: a retrospective review of children's medical records from 1985 to 2005

Introduction This study describes clinical and biochemical characteristics of nutritional rickets and risk factors at diagnosis among children living in Denmark. All medical records from patients with rickets referred to or discharged from hospitals in Southern Denmark from 1985 to 2005 were identified by register search. Materials and methods Patients included were younger than 15 years of age and fulfilled the diagnostic criteria of primary, nutritional rickets. A total of 112 patients with nutritional rickets were included: 29 were of ethnic Danish origin, and 83 were immigrants. Results Patients diagnosed before the age of 4 (median 1.4) years displayed the classic clinical signs of rickets, whereas patients diagnosed after the age of 4 (median 12.5) years had few clinical signs and unspecific symptoms. Ethnic Danish patients were only diagnosed before age 24 months, and they accounted for 73% of all cases presenting with hypocalcemic seizures, but biochemically, they did not have more severe rickets. Of patients diagnosed before the age of 4 years, 45% were ethnic Danish. In early childhood, insufficient or no vitamin D supplementation was given in 88% of all cases. Among immigrant girls older than 4 years of age, 78% were veiled. Discussion Nutritional rickets in Denmark is predominantly a disease among immigrants, but ethnic Danish patients comprised nearly half of all patients diagnosed before the age of 4 years, and they presented more frequently with hypocalcemic seizures. The main risk factors were omitted, such as vitamin D prophylaxis among the youngest patients and veiling among older children/teenagers.