The body continually attempts to eliminate chemical toxins through enzymatic processes in the liver. Urinary D-glucaric acid, a byproduct of phase I detoxification, is a valuable indicator of chemical exposure or liver damage. Urinary mercapturic acids are direct end product metabolites of conjugated xenobiotics. Combined assessment of the urinary levels of the two analytes provides valuable information about exposure to xenobiotics and liver disease, and the capability of the liver to eliminate toxins.
The production, use and disposal of toxic chemicals and synthetic materials have increased the risk of exposure to health threatening toxins. Causal relationships between toxic chemicals and diseases have been well established. However many patients endure chronic symptoms that are associated with exposure to toxins before advanced stages of specific diseases are realized. Thus, there is a great demand for noninvasive laboratory tests that can timely assess chemical exposure and the capability of hepatic detoxification.
One process by which the body eliminates toxins is enzymatic detoxification in the liver. A reliable biomarker for exposure to toxic chemicals is urinary D-glucaric acid. Elevated levels of D-glucaric acid indicate induction of cytochrome P-450 enzymes (phase I) as a result of exposure to many xenobiotics (e.g. pesticides, fungicides, petrochemicals, drugs, toluene, formaldehyde, styrenes, etc.) Such exposures induce the glucuronic acid enzymatic pathway and production of D-glucaric acid, thus urinary D-glucaric acid is an indirect by-product of chemical exposure and phase I detoxification reactions.
The urinary level of mercapturic acids indicates quantitatively the degree of activity, or capability of phase II detoxification. Mercapturic acids are the final excretory products of detoxification and include a variety of functionalized xenobiotics that have been conjugated with glutathione or L-cysteine prior to excretion. Low levels of mercapturic acids are consistent with insufficient levels of glutathione and/or cysteine. When the rate of formation of functionalized xenobiotics (phase I) exceeds the capacity of phase II detoxification, more potent toxins accumulate.
Especially important for symptomatic patients or those who have a history of chemical sensitivity, the noninvasive test does not require the use of hepatotoxic compounds. Thorough commentary and treatment recommendations are provided to simplify interpretation. Results are expressed per unit creatinine to normalize for dilution effects, and reference ranges are age and gender specific. It is highly recommended that a concentrated first morning urine specimen is submitted for analysis. The test does not replace comprehensive liver tests for cases of advanced liver disease