Vitamin D blood test may one day speed bipolar diagnosis in kids: Finding a reliable blood marker could offer help to doctors and parents, study suggests -- ScienceDailyThe clinical part of the pilot study was conducted at Harding Hospital at Ohio State's Wexner Medical Center and included 13 children without mood disorders, 12 children with diagnosed bipolar disorder and 11 children with major depressive disorder. Ziouzenkova said it made sense to look at vitamin D binding protein because it potentially plays a role in brain inflammation. The researchers also looked at inflammatory markers in the blood, but found no significant correlations. Looking for the nutrient vitamin D in the blood, as opposed to the binding protein, appears to have low diagnostic power, she said. "We wanted to look at factors that could be involved in mood disorders on a cellular level and that could be easily found in the blood," Ziouzenkova said. To date, finding a reliable blood marker for bipolar diagnosis has been elusive, she said. Her lab used an intricate technique to evaluate blood plasma, in which they essentially used biological "bait" to fish for inflammatory factors. That helped them identify the vitamin D binding protein as a potential diagnostic target.