Detection of renal tubular lesions after abdominal aortography and selective renal arteriography by quantitative measurements of brush-border enzymes in the urine.

Quantitative determination of brush-border enzyme excretion in the 24-hour urine is a much more sensitive index of renal tubular damage after aortography and selective renal arteriography than the conventional renal function tests such as serum creatinine and clearance determinations. Among the five brush-border enzymes which we investigated, alkaline phosphatase (AP) was the most sensitive diagnostic pointer. In 90% of hypertensive patients without detectable pre-existing renal parenchymal damage, abnormal levels of AP excretion in the urine were found on the same day as or on the day after the intra-arterial injection of contrast medium. Measurement of other brush-border enzymes does not provide any further diagnostic information. Provided there is no pre-existing renal parenchymal damage, the lesion caused by the contrast medium is transient and is usually reversed within 48 h. For the early detection of tubular lesions caused by tri-iodinated benzoic acid derivatives, AP excretion in the 24-hour urine should be measured at least twice--on the day of the contrast medium injection and on the following day.