Diurnal variation in angiotensin sensitivity in pregnancy

OBJECTIVE: Our purpose was to study the diurnal variation in angiotensin II sensitivity. STUDY DESIGN: Angiotensin sensitivity tests were performed at 9 AM and at 2 PM in 12 normotensive pregnant women, with each woman serving as her own control. RESULTS: In all patients the effective pressor dose was higher in the afternoon. CONCLUSION: We suggest the greater sensitivity to angiotensin in the morning is related to an intrinsic circadian variation in vascular reactivity. When the result of an angiotensin sensitivity test is interpreted, the time of day it is performed should be taken into account. (AM J OBSTET GYNECOL 1996;174:259-61.)