A Mathematical Model for Determining the Body's Fluctuating Need for and Synthesis of Active Vitamin D.

The process by which 1,25(OH)D is synthesized and degraded and how it is transported out of the cell and body is described. The changing demand for the synthesis of 1-25(OH)D during different conditions experienced by the body is reviewed. A method of determining 1,25(OH)D synthesis and demand, and the percent utilization of 25(OH)D to make 1,25(OH)D is presented based on the measurement of the end metabolites of 1,25(OH)D and of its immediate precursor, 25(OH)D. A mathematical model has been developed to allow the calculation of 1,25(OH) D synthesis, and demand, and the percent utilization of 25(OH)D. Simple algebraic equations have been derived which allow the calculation of these new parameters using the concentrations of the end metabolites of 1,25(OH)D and its immediate precursor, 25(OH)D in the serum and urine. Vitamin D plays an important role in combating invading bacteria and viruses and in subduing the body's associated inflammatory response. This new approach to evaluating vitamin D status may help clinicians determine 25(OH)D and 1,25(OH)D levels needed to suppress bacterial infections, viral replication during new viral infections and the reactivation of latent viruses, and to downregulate the inflammatory responses caused by bacteria and viruses.