Objective: The augmentation index (AIx) is a measure of arterial stiffness, and is an autonomous determinant independent of other cardiovascular risk factors.

Methods: We examined whether the peripheral and central blood pressure (BP), pulse rate, AIx of healthy volunteers, measured at three different times of the day (8 AM, 12 PM, 5 PM), would show any difference. The measurements were carried out using SphygmoCor device.

Results: 52 healthy volunteers were included into the study. The average age and BMI of the 23 males were 24.4±2.5 years and 24.0±2.9 kg/m2, while it was 23.0±1.4 years and 20.5±3.6 kg/m2 at the 29 females, respectively. During the three different times of measurement, the actual peripheral and central systolic and diastolic BP and pulse rate did not show any significant difference either for males, or females. In contrast, the AIx of the males was significantly reduced over the course of the day: 8 AM: 13.1±10.2%; 12 PM: 5.3±9.8%; 5PM: 3.4±8.2% (p<0,01). We observed a similar trend in the case of the females as well: 8 AM: 17.0±9.1%; 12 PM: 13.3±10.2%; 5 PM: 11.3±7.5% (p<0,01). The females AIx were higher than that of males (p<0,01).

Conclusion: We conclude that augmentation index shows a considerable diurnal variation and gender difference. There is a gradual decrease from morning values over the course of the day along. Our data suggest to take period of the day at which the measurement was taken and gender into account, while determining physiological and pathological values or interpreting test results.