Diagnostic strategies in urinalysis

The traditional methods in urinalysis (visual microscopy, qualitative test strip screening) were compared with automated microscopy (UA-1000, TOA-medicals, Japan) and quantitative single protein analysis in 562 fresh morning urine samples. Albumin served as "glomerular" and alpha 1-microglobulin as "tubular" markers measured by turbidimetry. The test strip delivered at least one positive result in 60% of the urine for blood (21%), leukocytes (27%), or protein (34%). In only 4% casts or renal cells were found by traditional microscopy, whereas automated microscopy was positive for these findings in 28% of the urine. Quantitative urine protein analysis alone exhibited results outside the reference interval in 52% of the urine. Combination of the test strip procedure for blood and leukocytes with urine protein analysis increased the number of positives to 73%. Thirteen percent of these additional findings were classified as glomerular (64%) and tubular (72%) proteinurias. In 7% of the urine a false positive protein test strip result was confirmed by quantitative albumin determination. Of 157 urine samples, positive in mechanized video recorded screening, 60 (38%) were normal in single protein analysis. The results allow for the conclusion that the advanced techniques are superior to traditional screening procedures in detecting abnormal urine composition. It is suggested that traditional urinalysis should be supported or replaced by quantitative determination of albumin and alpha 1-microglobulin. This recommended strategy is able to exclude or detect tubulo-interstitial nephropathies or microalbuminuria in earlier phases of renal complications, such as in diabetes mellitus, hypertension or in nephrotoxic injury. A fully mechanized version is suggested to meet appropriate quality criteria and economic needs.(ABSTRACT TRUNCATED AT 250 WORDS)