title: Efficiency of calcium absorption is not compromised in clinically stable prepubertal and pubertal girls with cystic fibrosis.
abstract: BACKGROUND
  Reduced bone mass is common in both children and adults with cystic fibrosis (CF) and may be a consequence of inadequate calcium absorption. The effect of CF on intestinal calcium absorption and retention has not been described in children.
  
  
  OBJECTIVE
  Calcium absorption and urinary losses were characterized in clinically stable girls with CF consuming self-selected diets and following usual pancreatic enzyme regimens.
  
  
  METHODS
  The percentage of calcium absorption was assessed in 23 girls (aged 7-18 y) with CF by using oral ((44)Ca) and intravenous ((42)Ca) stable isotopes. Girls were grouped according to Tanner stage of breast development. True calcium absorption (V(a)) was determined as the product of percentage calcium absorption and average 4-d daily calcium intake. Calcium balance was estimated by subtracting urinary calcium and estimated endogenous fecal losses from the measure of V(a). Analysis of variance was used to compare outcomes among pubertal groups, and regression analysis was used to describe the relations of percentage and total calcium absorption to calcium intake and of urinary calcium to sodium excretion.
  
  
  RESULTS
  Percentage calcium absorption was inversely related to calcium intake. Percentage absorption and V(a) were similar to values observed in healthy girls in other studies. Total calcium absorption and estimated calcium balance were significantly greater among girls in early puberty (Tanner stages 2-3) than in prepubertal or late-pubertal girls (P < 0.05). Urinary calcium was positively related to urinary sodium excretion (P = 0.02).
  
  
  CONCLUSIONS
  The efficiency of calcium absorption was not compromised in clinically stable girls with CF.
authors.affiliation: Center of Human Nutrition, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Schulze
authors.forename: Kimberly O
authors.initials: KO
authors.lastname: O'Brien
authors.forename: Emily L
authors.initials: EL
authors.lastname: Germain-Lee
authors.forename: David J
authors.initials: DJ
authors.lastname: Baer
authors.forename: Amanda
authors.initials: A
authors.lastname: Leonard
authors.forename: Beryl J
authors.initials: BJ
authors.lastname: Rosenstein
mesh_terms: D000042:Absorption; D000293:Adolescent; D015519:Bone Density; D002118:Calcium / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D002648:Child; D003550:Cystic Fibrosis / Q000378:metabolism*; D004032:Diet; D005260:Female; D006801:Humans; D009318:Natriuresis; D011627:Puberty
chemical_list: D002118:Calcium