Alkaline phosphatase urinary biomarkers

When considering the application of urinary enzymes to monitor subtle renal dysfunction and/ or to clarify mechanisms of nephrotoxicity, only a limited number of enzymes have been generally accepted as valuable urinary biomarkers. These include lactic dehydrogenase, N-acetyl-P-l>glucosarriitiidase (NAG), alanine aminopeptidase (AAP), intestinal alkaline phosphatase, glutathione-S-transferase, gamma-glutamyl transferase and fructose-l,6,-biphosphatase. 

The AHRQ Report summarized numerous studies that evaluated the effects of soy products, including both protein and isoflavones, on various markers of bone health, such as bone mineral density (BMD) and biomarkers related to bone formation (bone-specific alkaline phosphatase and osteocalcin) and resorption (urinary hydroxyproline, urinary pyridinoline, and urinary deoxypyridinoline). In general, no effect of soy consumption on BMD or on biomarkers of bone formation resulted. Although a number of studies observed reductions in markers of bone resorption, these were restricted to only two biomarkers urinary pyridinoline and deoxypyridinoline. Moreover, the effects were not consistent across studies. The AHRQ report found no consistent evidence of dose-response effects for either soy isoflavones or soy protein on markers of bone turnover (Balk et al., 2005). 

Since mercuric mercury mainly accumulates in the kidney, Hg causes severe nephrophathy, characterized by extensive loss of proximal tubule function and viability (Ganote et al. 1975). The renal toxicity of Hg " can be estimated by increases in urinary levels of biomarker enzymes, such as lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase, and y-glutamyltranspeptidase. Among these marker enzymes, alkaline phosphatase and aspartate aminotransferase are the most sensitive indicators, and lactate dehydrogenase is the most responsive marker to renal mercury toxicity (Dieter et al. 1992). 

---