Vitamin D and its metabolites. Advances in the diagnosis and treatment of rickets.

Diagnostic and therapeutical uses of vitamin D3 and its metabolites are reviewed. Special emphasis is dedicated to the fetomaternal relationships of 1,25 (OH)2 D3 and 25-OH-D3 at term. The serum levels of 1,25 (OH)2 D3 have been found to be higher in the maternal serum then in the corresponding fetus (85.3 pg/ml and 50.9 pg/ml, respectively). The highest serum levels of 1,25 (OH)2 D3 were found in October and the lowest ones in January showing that there is a dependence on the ultraviolet light. It has been found that there is a correlation between the fetomaternal serum levels of 1,25 (OH)2 D3 and 25-OHD. However, there is no correlation between the serum levels of 1,25 (OH)2 D3 and 25-OHD3, neither in the fetus nor in the mother.