The Relationship between Aldosterone to Renin Ratio and RI Value of the Uterine Artery in the Preeclamptic Patient vs. Normal Pregnancy

PURPOSE: Plasma levels of renin, angiotensin II and aldosterone are increased during normal pregnancy. However, these values in preeclampsia are decreased to nearly that of a nonpregnant subject, and vascular sensitivity to angiotensin II is increased. In preeclampsia, aldosterone is decreased less than rennin. Therefore current studies were undertaken to determine the relationship between aldosterone to renin ratio (ARR) and uterine artery perfusion via RI value. MATERIALS AND METHODS: In this study, the relationship between plasma aldosterone and renin concentration was determined in 27 preeclamptic women and 50 normal pregnant women, whose gestational weeks were matched. The aldosterone to renin ratio was calculated and compared between the two groups. Doppler velocimetry of the uterine artery, which was used to calculate resistance index (RI), was performed on all subjects. The relationship between ARR and RI value was reviewed. RESULTS: In the preeclampsia group, RI value of the uterine artery was significantly higher than that of normal pregnant women. Both plasma renin and aldosterone concentrations were lower in the preeclampsia group. However, the ratio of these two parameters was significantly higher (38.3 vs. 16.1, p < 0.001); the greater ARR, the higher the RI of the uterine artery (r2 = 0.053, p = 0.048). CONCLUSION: This study demonstrates that a high aldosterone to renin ratio may have a negative effect on perfusion of the uterine artery and play an important role in the pathophysiology of preeclampsia.