Direct analysis of un-derivatized asymmetric dimethylarginine (ADMA) and L-arginine from plasma using mixed-mode ion-exchange liquid chromatography-tandem mass spectrometry.

A high-throughput analytical method was developed for the measurement of asymmetric dimethylarginine (ADMA) and L-arginine (ARG) from plasma using LC/MS/MS. The sample preparation was simple and only required microfiltration prior to analysis. ADMA and ARG were assayed using mixed-mode ion-exchange chromatography which allowed for the retention of the un-derivatized compounds. The need for chromatographic separation of ADMA from symmetric dimethylarginine (SDMA) was avoided by using an ADMA specific product ion. As a result, the analytical method only required a total run time of 2 min. The method was validated by linearity, with r2>or=0.995 for both compounds, and accuracy, with no more than 7% deviation from the theoretical value. The estimated limit of detection and limit of quantification were suitable for clinical evaluations. The mean values of plasma ADMA and ARG taken from healthy volunteers (n=15) were 0.66+/-0.12 and 87+/-35 microM, respectively; the mean molar ratio of ARG to ADMA was 142+/-81.

Plasma homocysteine, fasting insulin, and androgen patterns among women with polycystic ovaries and infertility.

OBJECTIVE: To measure plasma homocysteine, androgen, and insulin concentrations in women with normal and polycystic-appearing ovaries in an infertility setting. METHODS: Among women referred for infertility evaluation (n = 54), homocysteine, androstenedione, DHEAS, total testosterone, fasting insulin/glucose and methyltetrahydrofolate reductase (MTHFR) polymorphism status (C677T mutation) were studied. Ovaries were examined via transvaginal sonogram by one observer and scored as either normal (n = 18) or polycystic (n = 36). RESULTS: When polycystic ovaries were identified, mean total testosterone was significantly higher than when non-polycystic ovaries were present (p = 0.01), although no measured androgen was outside the normal reference range in either group. Average BMI was higher in the polycystic group, but the difference was not significant (p = 0.10). We observed a trend toward higher mean fasting insulin levels in women with polycystic ovaries, but this increase did not reach statistical significance (p = 0.07). Median plasma homocysteine was identical (7.0 mmol/l) in both populations, and no study subject exceeded the current recommended maximum reference value. CONCLUSIONS: In this population, the presence of polycystic ovaries was associated with higher serum androgens (especially total testosterone) although none of the measured androgens were above the normal range. While fasting insulin levels were also higher in this group, median plasma homocysteine levels were similar irrespective of ovarian morphology. Concomitant plasma homocysteine derangements in this population of young, lean patients with polycystic-appearing ovaries seem unlikely. Further studies are needed to clarify the role(s) of homocysteine in human reproductive physiology.