Urinary zinc excretion in Crohn's disease.

In order to study the reliability of urinary zinc levels as an index of zinc metabolism and status in Crohn's disease, we evaluated plasma and urinary zinc concentrations, urinary 3-methylhistidine excretion, and Crohn's disease activity index (CDAI) in 42 patients affected by Crohn's disease. Plasma zinc correlated directly with albuminemia (P = 0.01) and inversely with CDAI (P = 0.001). Urinary zinc excretion correlated with urinary 3-methylhistidine (P = 0.001) and plasma zinc levels (P = 0.01), and inversely with CDAI (P = 0.05). However, from multiple regression analysis, it was found that zincemia is influenced by CDAI and not by albumin, whereas zincuria is related to urinary 3-methylhistidine and plasma zinc, and not to CDAI. Our conclusion is that, in Crohn's disease, zincuria can be an index of zinc status when used together with measurements of lean body mass and turnover and factors influencing plasma ultrafiltrable zinc fraction.