25-hydroxyvitamin D absorption in patients with Crohn's disease and with pancreatic insufficiency

Vitamin D malabsorption could be one possible reason for the high prevalence of vitamin D deficiency and osteopenia in patients with Crohn's disease (CD) and pancreatic insufficiency (PI). Hence, we performed a modified 25-hydroxyvitamin D (25-OHD) absorption test Stamp in 15 healthy controls, 31 patients with CD and 10 patients with PI. Serum 25-OHD levels were measured before, and 2, 4, 8, and 24 hours after oral administration of 5 micrograms 25-OHD/kg body weight. Basal 25-OHD levels were below the normal range of 12-36 ng/ml in 68% of patients with CD (median: 10; interquartile range: 4-12 ng/ml) and 70% of patients with PI (median: 3; interquartile range: 2-14 ng/ml). Peak levels were reached at 4 or 8 hours after ingestion of 25-OHD. Three patients with CD (10%) and 5 patients with PI (50%) showed decreased 25-OHD absorption. 25-OHD levels normalized in all but two patients with PI after 24 hours. Pattern of involvement or previous resections did not show a significant influence on 25-OHD absorption. Vitamin D malabsorption may be one reason for vitamin D deficiency in many patients with PI, but there is little evidence of vitamin D malabsorption in patients with CD. Oral 25-OHD administration seems to be a useful therapeutic alternative to native vitamin D in patients with possible malabsorption and vitamin D deficiency.