Refining simultaneous measurement of vitamin d and other secosteroids in human serum

"Vitamin D" refers to a group of closely related secosteroid compounds with demonstrated roles in bone and immune health in humans. Its deficiency has been causally linked to a range of adverse human health outcomes including renal failure and rickets. A bioactive metabolite of the vitamin known as calcitriol (1,25-dihydroxycholecalciferol) is hypothesized to enhance human neurology and cognition but rarely quantified simultaneously with other vitamin D metabolites, steroids, or hormones.The aim of this study was to develop and validate a simple, effective, and reliable method to measure major secosteroids and vitamin D metabolites in human serum with precision, accuracy, and sensitivity. A dynamic extraction method was designed with focus on six common vitamin D metabolites circulating in serum: cholecalciferol, calcidiol, and calcitriol from the D3 sub-family; and calciferol, ercalcidiol, and ercalcitriol from the D2. Analysis began with a test run to validate the novel method. Then, fifty (50) human serum biospecimens were obtained from adult Ugandans with and without chronic HIV infection. Thirty-two (32) species of vitamin D metabolites, other steroids, phytosterols, oxysterols, and hormones were identified and annotated by pure external standards. Relationships including serum lathosterol to cholesterol and calcidiol to ercalcidiol ratios were measured for preliminary comparison of groups by HIV and established for future study with an enlarged sample size. A goal for future applications is to identify associations between calcitriol bioavailability and diagnosed cognitive disorders or chronic diseases in longitudinal sampling.