A semiautomated procedure for urinary D-glucaric acid using a centrifugal analyzer

The most commonly used method for quantifying D-glucaric acid, the enzyme inhibition method, is a two-step procedure. In the first step of the present study, urine was boiled at acidic pH to convert glucaric acid to 1,4-glucarolactone, which inhibits beta-glucuronidase activity. In the second step, inhibition of beta-glucuronidase by the prepared urine was measured. This is an indirect measure of the D-glucaric acid concentration. The second step was adapted to a Cobas-Bio centrifugal analyzer. Values on a reference population obtained by the manual method were highly correlated with values obtained by the semiautomated method described here (r = 0.976, p = 0.25), and precision was comparable by the two methods. The throughput increased from 8 to 20 samples per day when the automated method was used.