Diamine oxidase content in urine of patients with renal failure.

Diamine oxidase activity was determined in twenty-seven samples collected from normal subjects and from patients with renal failure. The enzyme activity was absent or very low in the urine samples of normal subjects. The highest diamine oxidase activity was found in the patients affected with nephrosis, the Fanconi syndrome and renal transplantation, showing a relationship between urinary enzymatic activity and tubular damage, in accordance with the localization in the convoluted tubules.