Description of the urinary sediment as a tool for the diagnosis of nephropathies

Rolando Claure
Universidad Mayor de San Simon School of Medicine, Cochabamba, Bolivia.

Urinary sediment has been used as a diagnostic tool since the 17th century(1) and Pierre Rayer occupies a special place in the history of nephrology for his attempt to classify various diseases using this important diagnostic tool. Alongside his intern, Eugene Napoleon Vigla, Rayer revolutionized the study of kidney diseases by using microscopy to analyze urinary sediments, describing crystals, cells, casts, and yeasts(2, 3).

At the Hôpital de la Charité, a microscope became available in 1835 and Rayer promptly set up a program to investigate urinary sediment findings in various forms of kidney diseases. His proposed classification was based on clinical findings, urinary microscopy, and gross specimens whenever possible. Renal diseases were divided into acute nephritis with many red blood cells and too much albumin in the urine, and chronic albuminuric nephritis corresponding to what is now known as nephrotic syndrome. There was also mention of suppurative forms of nephritis, with pus cells in the urine, the result of either blood-borne or ascending infection of the kidneys(4).

After this first description, routine chemical analysis of urine and microscopic examination of the sediment were introduced during the first half of the 19th century. After a first wave of interest, the use of urinary sediment has progressively decreased(5); urinary microscopy analysis is now performed mostly in central laboratories and is infrequently performed by nephrologists who have lost the expertise to identify some types of casts and/or cells in order to perform clinical correlations(6). Nephrologists should reclaim this noninvasive test, since combining it with a comprehensive clinical evaluation and new biomarkers would provide new insights into renal diseases(7).


  1. 1.Armstrong JA. Urinalysis in Western culture: a brief history. Kidney Int. 2007;71(5):384-7.
  2. 2.Fogazzi GB, Cameron JS. The introduction of urine microscopy into clinical practice. Nephrol Dial Transplant. 1995;10(3):410-3.
  3. 3.Fogazzi GB, Cameron JS. Urinary microscopy from the seventeenth century to the present day. Kidney Int. 1996;50(3):1058-68.
  4. 4.Richet G. From Bright's disease to modern nephrology: Pierre Rayer's innovative method of clinical investigation. Kidney Int. 1991;39(4):787-92.
  5. 5.Eknoyan G. Looking at the urine: the renaissance of an unbroken tradition. Am J Kidney Dis. 2007;49(6):865-72.
  6. 6.Fogazzi GB, Garigali G. The clinical art and science of urine microscopy. Curr Opin Nephrol Hypertens. 2003;12(6):625-32.
  7. 7.Claure-Del Granado R, Macedo E, Mehta RL. Urine microscopy in acute kidney injury: time for a change. Am J Kidney Dis. 2011;57(5):657-60.

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