H-1-NMR DETERMINATION OF URINARY BETAINE IN PATIENTS WITH PREMATURE VASCULAR-DISEASE AND MILD HOMOCYSTEINEMIA

Urinary N,N,N-trimethylglycine (betaine) and N,N-dimethylglycine (DMG) have been identified and quantified for clinical purposes by proton n uclear magnetic resonance (H-1 NMR) measurement in previous studies. W e have assessed these procedures by using both one-dimensional (1-D) a nd 2-D NMR spectroscopy, together with pH titration of urinary extract s to help assign H-1 NMR spectral peaks. The betaine calibration curve linearity was excellent (r = 0.997, P = 0.0001) over the concentratio n range 0.2-1.2 mmol/L, and CVs for replicate betaine analyses ranged from 7% (n = 10) at the lowest concentration to 1% (n = 9) at the high est. The detection limit for betaine was <15 mu mol/L. Urinary DMG con centrations were substantially lower than those of betaine. Urinary be taine and DMG concentrations measured by H-1 NMR spectroscopy from 13 patients with premature vascular disease and 17 normal controls provid ed clinically pertinent data. We conclude that H-1 NMR provides unique advantages as a research tool for determination of urinary betaine an d DMG concentrations.