Can blood pressure variability be reconciled with interpretation of single measurements versus fixed thresholds?

A national governmental and two international bodies have recently defined normotension for persons 18 years of age or older. The World Health Organization (WHO), World Hypertension League (WHL) and U.S. National institutes of Health (NIH) recommend without further specification the use of 140/90 mm Hg (systolic, S/diastolic, D) blood pressure (BP) values as the upper limits of acceptability; no lower limits are given, except for the recommendation that '... unusually low readings should be evaluated for clinical significance'. We here report on a case tentatively diagnosed accordingly by casual time-unspecified office measurements as moderately hypertensive. When the same person is reexamined by ambulatory monitoring for 30 days, he is described as having an optimal BP on a given day and as Stage 2 hypertensive on a different day. These discrepant classifications do not only apply to single measurements. Multiple automatic measurements taken during office hours also fail to resolve the diagnostic problem approached by conventional criteria. Even in the case of ambulatory profiles covering 24 hours rather than office hours only, one cannot rely on arbitrary time-invariant dividing lines between an acceptable and an unacceptable BP. An alternative, chronobiologic approach is also described and discussed much more extensively much earlier, repeatedly elsewhere.