Urinary D-glucaric acid, a marker substance for microsomal enzyme induction. Methodological aspects, responses to alcohol and findings in workers exposed to toluene

Abstract

D-glucaric acid, an end product of glucuronic acid metabolism, has been used as a marker substance for microsomal enzyme induction. In this study a convenient microtitre-plate based method for the quantification of urinary D-glucaric acid has been developed and validated.

Mean urinary D-glucaric acid excretion in 20 healthy humans as measured by this method was 3.2μmol glucaric acid mmol⁻¹ creatinine, 95% confidence interval 3.0–3.4.

Moderate alcohol consumption in 18 healthy volunteers did not significantly augment the urinary D-glucaric acid excretion. Occupational exposition to toluene in a printing plant was investigated. In spite of considerable intra- and inter-individual variability, a significant difference between exposed (3.5, 3.1–3.9) and non-exposed (2.6, 2.2–3.0) workers was observed, p < 0.025. We conclude that the measurement of D-glucaric acid can be utilized for biological screening of enzyme induction on a group basis.

Key Words:

• biological monitoring
• enzyme induction
• microtitre-plates
• occupational hazards
• sugar acid
• toluene