of status phase I and phase II detoxification
of chemical exposure and impaired liver function
hepatotoxic challenge drugs required
first morning void urine collection
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
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
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
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.
Info courtesy of Doctor's Data.