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.
Lark
R K
RK
Department of Orthopaedics and the Department of Medicine, Divisions of Endocrinology, Pulmonary Medicine, and Critical Care Medicine, University of North Carolina, Chapel Hill, USA.
Lester
G E
GE
Ontjes
D A
DA
Blackwood
A D
AD
Hollis
B W
BW
Hensler
M M
MM
Aris
R M
RM
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