Small and large bowel surface area related to body weight and age related to the pathogenesis of fibrosing colonopathy in pédiatrie patients

Fibrosing colonopathy (FC), recently described in children with cystic fibrosis taking novel high-strength pancreatic enzyme supplements, is of uncertain pathogenesis, although direct damage to the colonie mucosa by a constituent of such preparations is one possible explanation. The strict limitation of the condition to pediatrie age group patients is not explained under such a model of local toxicity. The mucosal concentration of a toxic component of the preparations is a function of total mucosal surface area. However, dosing is based on body weight and does not take into account the possibility of age-related changes in bowel surface area proportional to body weight. The presence of such a relationship might explain the age distribution of FC. At present, this information is not available in the literature. The aim of the study was to determine the relationship between small and large bowel surface area and age/body weight in man. One hundred fifty-four consecutive pediatrie and adult postmortem examinations of patients without history or evidence of bowel disease or congenital malformation were included in the study (83 males, 71 females; age 0-40 years). At autopsy the postduodenal small bowel and large bowel (cecum to rectum inclusive) were removed from the body and their lengths measured separately. Specimens were then opened longitudinally and the mucosal width was determined at 10 systematically random locations distributed equidistantly throughout their length. For each case the mean mucosal widths of small and large bowels were calculated and multiplied by their respective lengths to determine the total mucosal surface areas. Division by body weight gave the surface area/body weight ratio (SA/BW ratio) of small and large bowels. The SA/BW ratio of the small bowel does not differ significantly between birth and 40 years (mean 30.7 cm /kg, range 17.9-52.7 cm /kg). In marked contrast, the SA/BW ratio for the large bowel increases significantly during teenage years from a stable mean of 5.7 cm /kg (age 0-12 years) to41.0cm2/kg (age 19.40years) (P < .001 ). The SA/BW ratio for the large bowel is significantly less than that for the small bowel between the ages of 0 and 14 years (P < .0005). There is no significant relationship between sex and SA/BW ratio for either small or large bowels. Results suggest that in children the concentration of any potential toxin at the colonie mucosa may be five times that in the small bowel. Similarly, for the same dose per unit body weight, the concentration in a child's colon may be seven times that in an adult. We believe these results provide an explanation for the restriction of fibrosing bowel disease in cystic fibrosis to the colon of children and support a hypothesis of local toxiciry for its pathogenesis. Copyright © 1997 Taylor & Francis.