title: Diurnal variation of flow-mediated dilatation in healthy humans.
abstract: BACKGROUND
  The measurement of flow-mediated dilatation (FMD) via ultrasound has been established as a reliable non-invasive measurement of endothelial function. However, the guidelines mention nothing regarding diurnal variation of FMD. Thus, we investigated the FMD in healthy people and diurnal variation of FMD.
  
  
  METHODS
  Twenty-five apparently healthy persons participated in this study. All participants had no history of cardiovascular diseases, hypertension, or diabetes and used any medication. For each volunteer, the measurements were repeated in the morning and afternoon on two different days. We checked capillary blood glucose, total cholesterol, triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL)-cholesterol.
  
  
  RESULTS
  The average of FMD measurements was 8.45% ± 2.39%. The mean values of systolic and diastolic blood pressure, heart rate, lipid profiles, and glucose levels were similar between the morning and afternoon measurements after 9-h fasting. There was no significant difference of FMD measurements between the morning and afternoon (8.32% ± 2.27% and 8.58% ± 2.56%, p = 0.329). Moreover, there was significant correlation between FMD in the morning and afternoon (r = 0.856, p < 0.001).
  
  
  CONCLUSIONS
  Our study shows measurement of FMD was 8.45% in healthy Koreans. Also, there was no significant difference of FMD measurements between the morning and afternoon.
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Yong Cheol
authors.initials: YC
authors.lastname: Kim
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea ; Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Kyeong Ho
authors.initials: KH
authors.lastname: Yun
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Sun Ho
authors.initials: SH
authors.lastname: Woo
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Jeong
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Lim
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Kyo Bum
authors.initials: KB
authors.lastname: Hwang
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Jeong
authors.affiliation: Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Mi Rim
authors.initials: MR
authors.lastname: Lee
authors.affiliation: Department of Public Health, Wonkwang University Graduate School, Iksan, Korea.
authors.forename: Jeong Mi
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea ; Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Sang Jae
authors.initials: SJ
authors.lastname: Rhee
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea ; Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Nam-Ho
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea ; Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Seok Kyu
authors.initials: SK
authors.lastname: Oh
authors.affiliation: Departments of Cardiovascular Medicine, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea ; Regional Cardiocerebrovascular Center, Wonkwang University School of Medicine and Hospital, 895 Muwang-ro, Iksan, Jeonbuk 570-711 Korea.
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Jeong
keywords: Circadian variation; Diurnal variation; Flow-mediated dilatation