to ascertain the activity of the vitamin d biosynthetic pathway , the serum concentration of 1,25-dihydroxyvitamin d ( calcitriol ) was measured in 16 preterm infants ( 32 to 37 weeks of gestation ) at 1 to 2 and 120 hours of age .
C0012328
dihydroxyvitamin d
C0006674
calcitriol