This test provides valuable information about exposure to xenobiotics, liver disease and the ability 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 provide timely assessment of 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, including pesticides, fungicides, petrochemicals, drugs, toluene, formaldehyde, styrenes and more. Such exposures induce the glucuronic acid enzymatic pathway and production of D-glucaric acid, thus urinary D-glucaric acid is an indirect byproduct 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, this test does not require the use of hepatotoxic compounds. This non-invasive test requires only a single, first morning void (FMV) urine collection. Results are expressed per unit creatinine to normalize for dilution effects, and reference ranges are age and gender specific. The test does not replace comprehensive liver tests for cases of advanced liver disease.