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.

1 Biochemical, Pathobiochemical, and Morphological Fundamentals of the Excretion of Urinary Enzymes

1 Origin of Enzymes in Urine
2 Distribution of Diagnostically Relevant Enzymes Along the Nephron
3 Mechanisms of Enzyme Release and Causes of Altered Enzyme Excretion
4 Enzymuria as an Indicator of Renal Pathomorphology
5 Physiological Factors Influencing Enzyme Excretion
2 Methodological Fundamentals of the Activity Determination of Urinary Enzymes
6 Preanalytical Treatment of Urine
7 Quality Assurance
8 Methods for Measuring Urinary Enzyme Activities
9 Basis of Reference
10 Reference Intervals
3 Urinary Enzymes in Clinical Medicine
11 Clinical Interpretation of Urinary Enzyme Excretion
12 Urinary Enzymes in Renal, Renal-Associated and Urological Disorders
13 Urinary Enzymes in Kidney Transplantation
14 Urinary Enzymes and Nephrotoxicity in Humans
15 Extrarenal Diseases
4 Urinary Enzymes in Animal Experiments
16 Animal Models
17 Reference Values
18 Influence of Different Substances on Urinary Enzyme Excretion
5 Nephrotoxicity
19 Renal Enzymes as the Basis for Alternative Methods of Safety Screening In Vitro and Understanding the Mechanism of Nephrotoxicity.