Serum Concentrations of Vitamin D Metabolites in Children with Various Diseases and Two Cases of Rickets with Persistently Low Serum 25-OH-D Levels(Metabolic Bone Disease in Vanious Fields of Medicine)

We measured serum concentrations of 25-OH-D, 1,25-(OH)_2 D, and 24,25-(OH)_2 D in children with various diseases. The serum 25-OH-D levels were decreased in congenital biliary atresia, hypophosphatemic rickets, and epilepsy. The serum concentrations of both 1,25-(OH)_2 D and 24,25-(OH)_2 D were decreased in congenital nephrotic syndrome and congenital biliary atresia. No significant relations were demonstrated among these vitamin D metabolites. However, a significant correlation was found between the serum concentrations of 25-OH-D and alkaline phosphatase. In these consecutive studies, two children showing characteristic signs of rickets were found to have persistently low serum 25-OH-D levels with normal 1,25-(OH)_2 D levels. They responded to a large dose of vitamin D_2 followed by an increase of serum 25-OH-D level, and which suggested a new type of vitamin D refractory rickets due to impaired 25-hydroxylation in the liver