Diminished and erratic absorption of ergocalciferol in adult cystic fibrosis patients.
BACKGROUND
Osteoporosis diminishes the quality of life in adults with cystic fibrosis (CF). Vitamin D deficiency resulting from malabsorption may be a factor in the etiology of low bone mineral density (BMD) in patients with CF.


OBJECTIVE
Absorption of oral ergocalciferol (vitamin D2) and the consequent response of 25-hydroxyvitamin D in 10 adults with CF and exocrine pancreatic insufficiency was compared with that of 10 healthy control subjects.


METHODS
In this pharmacokinetic study, CF patients and control subjects were pair-matched on age, sex, and race. Each subject consumed 2500 microg oral vitamin D2 with a meal. The CF group also took pancreatic enzymes that provided > or = 80000 U lipase. Blood samples were obtained at baseline and at 5, 10, 24, 30, and 36 h after vitamin D2 consumption to measure serum vitamin D2 and 25-hydroxyvitamin D concentrations.


RESULTS
Vitamin D2 concentrations in all subjects were near zero at baseline. CF patients absorbed less than one-half the amount of oral vitamin D2 that was absorbed by control subjects (P < 0.001). Absorption by the CF patients varied greatly; 2 patients absorbed virtually no vitamin D2. The rise in 25-hydroxyvitamin D in response to vitamin D2 absorption was significantly lower over time in the CF group than in the control group (P = 0.0012).


CONCLUSIONS
Vitamin D2 absorption was significantly lower in CF patients than in control subjects. These results may help explain the etiology of vitamin D deficiency in CF patients, which may contribute to their low BMD.
Department of Orthopaedics and the Department of Medicine, Divisions of Endocrinology, Pulmonary Medicine, and Critical Care Medicine, University of North Carolina, Chapel Hill, USA.
R K
RK
Lark
G E
GE
Lester
D A
DA
Ontjes
A D
AD
Blackwood
B W
BW
Hollis
M M
MM
Hensler
R M
RM
Aris
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D015519:Bone Density; D016022:Case-Control Studies; D003550:Cystic Fibrosis / Q000150:complications / Q000378:metabolism*; D004872:Ergocalciferols / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010188:Exocrine Pancreatic Insufficiency / Q000097:blood / Q000150:complications; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D008049:Lipase / Q000008:administration & dosage / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood
D004872:Ergocalciferols; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D008049:Lipase