Measurement of asymmetric dimethylarginine (ADMA) in human plasma: from liquid chromatography estimation to liquid chromatography-mass spectrometry quantification
- First Online:
- Cite this article as:
- Martens-Lobenhoffer, J. & Bode-Böger, S.M. Eur J Clin Pharmacol (2006) 62(Suppl 1): 61. doi:10.1007/s00228-005-0015-9
- 151 Downloads
Nitric oxide (NO) is synthesized from L-arginine (ARG) by NO synthase (NOS), which can be inhibited by endogenous inhibitors such as asymmetric dimethylarginine (ADMA). A growing number of clinical studies documented a tight correlation between increased ADMA blood levels and cardiovascular morbidity and mortality. Therefore, it is highly desirable to measure ARG and its metabolites in human biological fluids. A broad range of analytical methods for the determination of ARG, ADMA, and symmetric dimethylarginine (SDMA) has been published, but there are large discrepancies in the concentration values obtained from these methods. We here describe a reference method for the determination of circulating ARG, ADMA, and SDMA, which relies on the high-performance liquid chromatography (HPLC) separation of the o-phthaldehyde derivatives of the analytes and their subsequent mass spectrometric (MS) detection. This method overcomes the problems of extensive sample preparation, unspecific detection, and external calibration. The use of isotope-labeled internal standards for ARG and ADMA leads to very precise and accurate results. With this method we found in healthy volunteers (n=47, age 20–56 years) plasma concentrations of (mean±standard deviation) 63.9±23.9 μmol/l for ARG, 0.355±0.066 μmol/l for ADMA, and 0.460±0.092 μmol/l for SDMA.