Effect of Conjugated and Unconjugated Hyperbilirubinaemia on the Plasma 25-Hydroxy-Vitamin D Response to Ultraviolet Radiation in the Rat

1. Vitamin D deficiency was induced in anicteric Wistar rats, Wistar rats before common bile-duct ligation was performed and Gunn rats with unconjugated hyperbilirubinaemia.

2. The effect of ultraviolet radiation on plasma concentrations of 25-hydroxy-vitamin D was studied in a group of control anicteric Wistar rats (n = 11), Wistar rats 8 days after common bile-duct ligation (n = 7) with conjugated hyperbilirubinaemia and in Gunn rats (n = 11).

3. The plasma 25-hydroxy-vitamin D response to ultraviolet radiation was similar in the three groups.

4. It is suggested that neither conjugated nor unconjugated hyperbilirubinaemia prevent cutaneous vitamin D₃ synthesis or 25-hydroxylation in the rat.