K. Kawasaka et N. Tatsumi, D-AMINO-ACID OXIDASE ACTIVITY IN URINE OBTAINED FROM PATIENTS WITH RENAL DISORDERS, Clinical nephrology, 49(4), 1998, pp. 214-220
D-amino acid oxidase (DAO) is an enzyme released from the kidney, and
a method for its enzymatic assay was developed by our group for urine
specimens. A clinical evaluation of the test was performed for healthy
individuals and patients with various types of nephropathy. 1) The no
rmal reference interval was 0-10.0 mu g/g Cr for randomly-collected ur
ine. The intra-assay CV was 3.5-9.4%, and the inter-assay CV was 4.5-9
.8%. 2) Urinary DAO index correlated well with changes in urinary micr
oalbumin and N-acetyl-beta-glucosaminidase. 3) Chronic renal failure g
enerally showed high levels of DAO, except for nephrotic syndrome, in
which changes were minimal after the acute stage. In the nephrotic syn
drome, urinary DAO was elevated in the acute stage with high proteinur
ia, but went down to almost normal as the proteinuria improved, althou
gh DAO changes did not correlate with the changes in the degree of pro
teinuria in lupus nephritis. 3) DAO changes were more sensitive than t
hose of N-acetyl-beta-glucosaminidase or alpha(1)-microglobulin in the
clinical course of renal disorders. From these findings, DAO was judg
ed to be very useful for monitoring the severity of renal dysfunction.