The Value of Microscopic Examination of Urinary Sediment

Abstract

To the Editor.— An article appeared in The Journal entitled Microscopic Look at Urine Often Unnecessary (239:13, 1978). This report indicated that a low diagnostic yield was seen on microscopic examination if findings from a macroscopic urinalysis were negative. On the contrary, I think that microscopic findings may be meaningful even where findings from macroscopic studies, including chemical screening tests, are negative. I found this to be true in 1967 when I reported a study of 10,140 specimens. To see whether the conclusions drawn then are still valid, earlier this year I had a new study done on microscopic specimens by a laboratory that serves a great number of insurance companies and analyzes as many urine specimens as any other laboratory in the world. The processing technique for urinalysis involves centrifuging the 15-ml specimen at 3,000 rpm in a standard clinical centrifuge for four minutes. Then, 0.05 ml of the