Low serum zinc concentrations have been reported in Crohn's disease (CD) and overt zinc deficiency has been described, but little is known about the effect of CD on zinc metabolism in adolescents. The aim of this study was to measure zinc absorption, endogenous fecal zinc excretion, urinary zinc excretion, and zinc balance in children with stable CD and in matched controls. Subjects were 15 children, ages 8 -18 y, with stable CD, and 15 healthy matched controls. Subjects were adapted to diets providing 12 mg/d elemental zinc for 2 wk, and then admitted for a 6-d metabolic study. Stable zinc isotopes were given intravenously and orally, and urine and feces collected for 6 d. Fractional zinc absorption, endogenous fecal zinc excretion, and zinc balance were calculated using established stable isotope methods. In subjects with CD, zinc absorption (10.9% Ϯ 6.1 versus 23.4 Ϯ 15.8, p ϭ 0.008) and plasma zinc concentration (0.85 mg/dL Ϯ 0.15 versus 1.25 Ϯ 0.35, p ϭ 0.004) were significantly reduced, compared with controls. Despite this, there were no significant differences in endogenous fecal zinc excretion (2.0 mg Ϯ 1.5 versus 1.5 Ϯ 1.5, p ϭ 0.34) or urinary zinc excretion (0.9 mg Ϯ 0.7 versus 1.0 Ϯ 0.7, p ϭ 0.47). Zinc balance was significantly lower in CD (Ϫ1.5 mg Ϯ 1.5) than in controls (ϩ0.6 mg Ϯ 3.1, p Ͻ 0.0001). In conclusion, adolescents with CD have significantly reduced zinc absorption. Despite this, they were unable to reduce endogenous fecal zinc excretion to restore normal zinc balance and had a significantly worse zinc balance and lower plasma zinc concentration than controls. Crohn's disease (CD) is a chronic, progressive inflammatory disorder that can affect the entire length of the gastrointestinal tract. Children with CD often present with growth stunting, weight loss, and nutritional deficiencies due to anorexia, poor intestinal absorption, and increased losses of nutrients in the gastrointestinal tract (1).Zinc is a component of over 200 enzymes and is essential for normal immune function, DNA and RNA synthesis, and gene transcription. Zinc is absorbed along the length of the small intestine and is transported to the liver in the portal circulation. It is excreted into the gut (endogenous fecal zinc excretion), and pancreatic and biliary secretions contain large amounts of zinc, most of which is subsequently reabsorbed. Zinc homeostasis is maintained by changes in fractional zinc absorption and in endogenous fecal zinc excretion (2). Endogenous fecal zinc excretion increases during periods of high zinc intake (3) and decreases during periods of zinc restriction (4).Severe zinc deficiency leads to clinical features of acrodermatitis such as alopecia, anorexia, diarrhea, dermatitis, poor growth, and impaired immune function, and children are at especially high risk for zinc deficiency due to their high requirements for normal growth (2). Zinc deficiency was first reported in CD in the 1970s (5-7), and, in extreme cases, the clinical features of acrodermatitis have been described (8 -11). The incidenc...