title: Fat malabsorption in cystic fibrosis: comparison of quantitative fat assay and a novel assay using fecal lauric/behenic acid.
abstract: OBJECTIVE
  The gold standard for the diagnosis of fat malabsorption, the 72-hour fat balance study, requires a 3-day collection to generate a coefficient of fat absorption (CFA). We hypothesized that a new test using behenic acid (behenate test) as a nonabsorbable lipid marker may provide a facile means to assess fat absorption. The study proposed to answer 2 questions: first, whether the behenate test correlated with the gold standard and, second, whether the CFA improved when taking pancreatic enzymes during meals instead of taking them before meals.
  
  
  METHODS
  The study compared the behenate test with the gold standard in 15 patients with cystic fibrosis during 3 arms that require 3- to 4-day hospitalization: first, taking pancreatic enzymes before meals; second, taking it during meals; and third, without taking it.
  
  
  RESULTS
  The mean CFA was 78.3% when pancreatic enzymes were taken during meals and 80.4% when these enzymes were taken before meals. Correlation between the CFA and the behenate test for collections during all 3 arms was r = 0.219 (P = 0.001).
  
  
  CONCLUSIONS
  Timing of ingestion of pancreatic enzymes does not significantly alter the CFA. Although the CFA correlates with the behenate test, the correlation is not robust enough to justify replacement of the gold standard by this test. It is unclear whether the poor correlation between tests relates to intermeal variability in fat excretion or other factors; however, the behenate test may be suitable as a screening test for the detection of fat malabsorption.
authors.affiliation: Nemours Children's Clinic, Jacksonville, FL, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Dorsey
authors.forename: Donna
authors.initials: D
authors.lastname: Buckley
authors.forename: Suzanne
authors.initials: S
authors.lastname: Summer
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Jandacek
authors.forename: Therese
authors.initials: T
authors.lastname: Rider
authors.forename: Patrick
authors.initials: P
authors.lastname: Tso
authors.forename: Michael R
authors.initials: MR
authors.lastname: Narkewicz
authors.forename: James E
authors.initials: JE
authors.lastname: Heubi
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D019963:Clinical Chemistry Tests / Q000379:methods*; D003550:Cystic Fibrosis / Q000150:complications / Q000188:drug therapy / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D019587:Dietary Supplements; D004334:Drug Administration Schedule; D057487:Enzyme Therapy; D004798:Enzymes / Q000008:administration & dosage*; D005227:Fatty Acids / Q000032:analysis*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007850:Lauric Acids / Q000032:analysis*; D008286:Malabsorption Syndromes / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010179:Pancreas; D013997:Time Factors; D055815:Young Adult
chemical_list: D004041:Dietary Fats; D004798:Enzymes; D005227:Fatty Acids; D007850:Lauric Acids; C030358:lauric acid; C007547:behenic acid