MALONDIALDEHYDE MEASUREMENT IN URINE

Malondialdehyde (MDA) is an end product of lipid peroxidation and is a frequently measured index of these processes. The thiobarbituric acid (TBA) test is commonly used to measured MDA, but its specificity is q uestionable due to the presence of interfering chromogens. Wade and va n Rij described in 1988 a method which removes these chromogens by HPL C. However, the sensitivity and the resolution of this method was not adequate for measurements of MDA in urine. We have improved this metho d by replacing TBA with diethylthiobarbituric acid (DETBA). The less p olar MDA-DETBA complexes were isolated on Bakerbond cartridges and qua ntified by HPLC without interference. MDA was detectable using a fluor escence or ultraviolet detector at picomole levels. This technique was applied to urine samples obtained from ten burns patients on differen t days following their hospitalization. Urinary MDA in burns patients was very high and reached 18.6 mu mol/mmol creatinine in one patient c ompared with a mean value of 0.23 mu mol/mmol creatinine in healthy co ntrols. Maximum MDA levels were attained on the third day for the majo rity of patients and remained, on average, much higher than normal eve n after 20 days. Using this method, picomole quantities of MDA can be easily and specifically detected in urine samples. This method is usef ul for assessing an oxidative stress.