Submitted to: Journal of Pediatrics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/21/2003
Publication Date: 8/22/2003
Citation: Schulze, K.J., O'Brien, K.O., Germain-Lee, E.L., Baer, D.J., Leonard, A., Rosenstein, B.J. 2003. Endogenous fecal losses of calcium compromise calcium balance in girls with cystic fibrosis. Journal of Pediatrics. Interpretive Summary: This study was designed to investigate calcium metabolism and the impact of endogenous calcium losses in girls with cystic fibrosis. Bone loss is a major complicating sequel of cystic fibrosis. Previous research has demonstrated that calcium absorption and urinary excretion are similar between girls with cystic fibrosis and those without the disease. Using stable isotope methods, the impact of endogenous calcium losses (calcium of non-dietary sources that are secreted into the gastrointestinal tract during the process of digestion) on calcium balance. Results of this study suggest that endogenous calcium losses are a significant source of calcium loss in individuals with cystic fibrosis, and that endogenous losses may be related to nutritional status and gut function in CF. These data are important for physicians and dieticians treating patients with cystic fibrosis and for patients with cystic fibrosis.
Technical Abstract: Bone mineral density is compromised in individuals with cystic fibrosis (CF); calcium (Ca) is the major bone mineral. This study examined the impact of endogenous fecal calcium (Vendo) on calcium balance in girls with CF. Vendo was measured in 12 girls with CF (ages 7-18 y). Volunteers made up two groups: younger, premenarcheal girls with compromised nutritional status; older, postmenarcheal girls with adequate nutritional status. Vendo was determined by the appearance of intravenously administered 42Ca, a calcium stable isotope, in stool relative to urine over 6-d. Vendo was compared between pre- and postmenarcheal girls by Student's t-test. Actual calcium balance [absorbed calcium - (urinary calcium + Vendo)] was compared with estimated balance (assuming Vendo = 1.6 mg Ca/kg/d) by paired t-test. Vendo was 99.3 +/ -42.3 mg Ca/d. By body weight, losses were highest among premenarcheal girls (3.37 +/- 1.09 mg Ca/kg/d), resulting in excess losses (> 1.6 mg Ca/kg/d) of 55.0 +/- 45.7 mg Ca/d. Over one year, this represents 20.1 +/- 16.7 g of unattained bone calcium, or 6.7 +/- 4.2% of the bone calcium content of these girls. Vendo is a significant source of calcium loss in individuals with CF. Vendo may be related to nutritional status and gut function in CF.