Ebook: Urinary Enzymes: in Clinical and Experimental Medicine

Interest and research in urinary enzymology were incited about three decades ago by reports that urinary enzymes are elevated in diseases of the kidney and urinary tract. Of the more than 40 hydrolases, oxidoreductases, transferases, and lyases identified in human and animal urine, only ten or so are being used as diagnostic indicators. Recognition of the quantitative distribution of enzymes in the various anatomical and functional parts of the nephron and advances in our understanding of the handling of proteins by the kidney have made it possible to associate urinary enzyme activity patterns with physiological and pathophysio­ logical functions of the nephron. Confidence in the diagnostic value of urinary enzymes is not unanimous among clinicians and among scientists. The main reason for the difference in opinion may well be that the variability in data exceeds the variability one is accustomed to in the diagnostic enzymology of blood plasma enzymes. In contrast to plasma enzymes, which are protected by an "enzyme friendly" milieu, enzymes released into the urine encounter an "enzyme hostile" environ­ ment: no or little protective protein, variable pH, variable volume, variable metabolite and salt concentrations, variable concentrations of enzyme in­ hibitors. Through advances in methodology some of these factors can now be controlled; standardization of urine collection periods and preanalytical treat­ ment are as important as optimization of assay methods.

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The book provides a comprehensive uptodate review of the present state of knowledge of urinary enzymes. Since it deals with all the essential questions currently being discussed in connection with urinary enzymes, it will be of interest to biochemists, clinical chemists, renal physiologists, nephrologists and clinicians working on renal problems.The chapters are grouped into 5 parts, the first offeringan update of the biochemical and morphological fundamentals of the excretionof urinary enzymes, including a description of the distribution of diagnostically relevant enzymes along the nephron, the mechanisms of enzyme release, and the physiological factors influencing the excretion rate. The chapters in the second part deal with the methodological fundamentals ofthe activity determination of urinary enzymes (preanalytical treatment, quality assurance, methodical details for the most important enzymes, reviewon reference intervals). The four chapters in the third part review aspects of urinary enzyme excretion in clinical medicine (renal, renal associated, and urological disorders, kidney transplantation, nephrotoxicity, extrarenal diseases) and includes a special chapter on the general background for interpreting data on urinary enzyme excretion. The fourth part, consisting of 3 chapters, covers urinary enzymes in animal experiments (animal models, influence of different substances on urinary enzyme excretion, reference values in various animals). The book concludes with a review of the posibilities for using renal enzymes as the basis for alternative methods of screening toxic substances.