Measurement of plasma (serum) 25(OH)D3, levels, (the precursor of active vitamin D) is the current method of evaluating vitamin D status. The measurement of active vitamin D, 1,25(OH) 2 D 3 and its precursor, 25(OH)D 3 , in the serum does not always reflect the overall active vitamin D synthesis and utilization by the body. This may be especially true during periods of increased demand for this hormone. Active vitamin D synthesis and degradation can occur simultaneously and is often entirely an intracellular process. The process whereby much of active vitamin D is synthesized and degraded and how it is transported out of the cell and body is presented. A method of determining active vitamin D levels, synthesis, degradation, and utilization is also presented based on the measurement of the end metabolites of active vitamin D and of its precursor vitamin D.
Unlike other vitamins, active vitamin D is a hormone acting on many receptor sites in the body and it is an essential modulator of the immune system. The vitamin D hormone plays an active role in the initial suppression of invading microbials including viruses and in subduing the body’s inflammatory response to acute viral infections and reactivation of latent viruses. The conversion of precursor vitamin D supplements to active vitamin D may be hindered in individuals with elevated body mass Index (BMI) or percent body fat when initial stores of vitamin D precursors are low and demand for active vitamin D increases suddenly such as during acute systemic infections, trauma, or other physiological stressors.
In this paper, a molar balance approach involving vitamin D end metabolites is used to estimate fluctuating active vitamin D levels, synthesis, and demand. The ability to estimate active vitamin D levels, and synthesis may allow the establishment of actual active vitamin D levels in the body needed to suppress COVID-19 virus replication and to decrease COVID-19 virus stimulation of an exaggerated immune system inflammatory response. Determining actual active vitamin D levels and percent utilization/demand may prove vital in the treatment and monitoring of individuals with acute and sometimes life-threatening infections. This new information may allow clinicians to quickly adjust intervention with calcitriol, active vitamin D, 1,25(OH) 2 D 3 , in order to achieve rapid suppression of viruses such as the COVID-19 virus and improvement in immune system’s ability to control its inflammatory response.