An appraisal of CSF glutamine measurement by acid hydrolysis

The hydrolysis of CSF glutamine as proposed by Harst et al. (2) was shown to be incomplete due to the low acid concentration in the reaction. Complete hydrolysis was achieved with a higher acid concentration. Because glutamine is stoichiometrically converted to ammonia and glutamic acid, both ammonia and glutamine can be used as standard solutions. It was further shown that glutamine standard solution, even though deaminated, can still be used. CSF urea, if very high, will give falsely elevated glutamine concentrations. Correction is possible by subtraction of its glutamine equivalent value. An optimum Berthelot reaction was developed for our modified assay.