Université Catholique de Louvain, Bruxelles, Belgium
The abundance of diagnostic tools so characteristic of the latter part of the 20th century has eroded the clinical skills, the critical evaluation of the significant elements of a patient's history, and clinical signs. Junior physicians are flabbergasted by the information extracted by their seniors from a detailed, painstaking, time-consuming clinical examination. The meticulous examination of the urinary sediment is part of that shrinking heritage. Stewart Cameron introduces this excellent book by Fogazzi et al. with a pleasant review of the history of urinalysis.
Chapter 2 (pp. 29134) offers a magnificently illustrated review of the formed elements present in the urinary sediment. The diagnostic yield of these observations is summarized in chapter 3 (pp. 135137) reporting the normal range of erythrocyte and leukocyte urinary output, in chapter 4 (pp. 139160) describing sediment abnormalities observed in various clinical diseases, and in chapter 6 (pp. 167173) classifying urine sediment findings into patterns and listing their clinical counterparts. A few interesting pages (chapter 5, pp. 161165) summarize available data on drug related crystalluria. They provide a good reference for microscopists confronted with puzzling images.
The technical requirements to obtain and adequately handle urine samples are outlined in chapter 1 (pp. 1328). The book concludes with newer automated methods for urinary sediment analysis (chapter 7, pp. 175181). This latter contribution is welcome as it introduces nephrologists to techniques of flow cytometry adapted from the haematology laboratory. Their critical understanding is mandatory to interpret results given in traditional units (cells per µl or per HPF) despite a completely different methodological approach.
Overall this book provides a richly illustrated review of all formed elements found in the urinary sediment. Still, the clinical nephrologist misses a concise, sharp outline of the rare elements providing a precise diagnosis. For instance, red cell casts are usually taken to indicate not only parenchymal (p. 74) but more precisely glomerular bleeding. They remain for most nephrologists interested in the urinary sediment, the hallmark of a glomerular lesion. A single report of acute interstitial nephritis associated red cell cast is not sufficient to detract from this approach. Similarly, the presence of cystine crystals in the urine indicates cystinuria. No other crystal has the same diagnostic yield.
There will never be enough emphasis on the irreplaceable value of an experienced microscopist in the laboratory. Many major renal units ignore the usefulness of the urinary sediment as the consequence of the absence of a skilled technician. Examination of the urine sediment is unfortunately time consuming and not cost-effective for a central laboratory. Flow cytometry now allows the selection of those samples that require a specific microscopic analysis. This approach, not yet discussed in chapter 7, will undoubtedly find its place in the third edition!
These few comments should not obscure the significant contribution of The urinary sediment to the diagnostic armamentarium of the nephrologist. Each renal unit should have a copy available for daily clinical discussions. The pathology laboratory will find it very important for the technicians in charge of urinary sediment. Finally, this book should be included in the required reading list of courses in renal medicine.