Monitoring of 25-OH vitamin D levels in children with cystic fibrosis.
BACKGROUND
Patients with cystic fibrosis are at risk for malabsorption of fat-soluble vitamins, and those with low 25-OH vitamin D levels have a higher risk of low bone mineral density and long-term skeletal complications. It is currently recommended that vitamins A and E be monitored yearly; however, no recommendations exist for 25-OH vitamin D. Because all three vitamins are fat-soluble, the hypothesis in the current study was that low levels of vitamins A and E could identify patients at risk for low 25-OH vitamin D, so that 25-OH vitamin D measurements could be obtained in only selected circumstances.


METHODS
Forty (21 girls) patients with CF, age 10.5 +/- 3.9 (SD) years, were assessed in a cross-sectional survey for ideal weight for height (percentage of predicted), spirometry (percentage of predicted FEV1, 33/40 patients), and serum levels of vitamins A, E, 25-OH vitamin D, and cholesterol (37/40 patients).


RESULTS
Nine (22.5%) of 40 patients were malnourished (percentage of predicted ideal weight for height <85%), 7 (21.2%) of 33 had moderate to severe lung disease (FEV1 <60%), 4 (10%) of 40 had low levels of vitamin A, 3 (7.5%) of 40 had low vitamin E levels, 4 (10.8%) of 37 low vitamin E/cholesterol levels, and 4 (10%) of 40 had marginal or low levels of 25-OH vitamin D (<40 mmol/l). The patients with low 25-OH vitamin D were older, with no child < 12 years of age having a 25-OH vitamin D level less than 40 mmol/l. They also had lower vitamin E and vitamin E/cholesterol levels than those with normal 25-OH vitamin D levels. The groups did not differ in percentage of predicted ideal weight for height, lung function, or vitamin A levels. The best positive predictor for 25-OH vitamin D less than 40 mmol/l was low vitamin E (66.7%), with a negative predictive value of 94.6%. 25-OH vitamin D levels correlated with vitamin E/cholesterol levels (r = 0.41, P < 0.01) and weakly with vitamin E levels (r = 0.28, P < 0.08), but not with vitamin A levels.


CONCLUSIONS
These results suggest that children aged less than 12 years and older children with normal vitamin E levels are especially unlikely to have low 25-OH vitamin D levels, and this measure can therefore be omitted. In contrast, those children with low vitamin E levels may warrant monitoring.
Grey
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Department of Biochemistry, McGill University Health Centre-Montreal Children's Hospital, Quebec, Canada.
Lands
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Pall
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Drury
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D000293:Adolescent; D000375:Aging; D002112:Calcifediol / Q000097:blood*; D002648:Child; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000097:blood* / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D009748:Nutrition Disorders / Q000209:etiology; D014802:Vitamin A Deficiency / Q000209:etiology; D014808:Vitamin D Deficiency / Q000175:diagnosis / Q000209:etiology; D014810:Vitamin E / Q000097:blood; D014811:Vitamin E Deficiency / Q000209:etiology
D014810:Vitamin E; D002784:Cholesterol; D002112:Calcifediol