Etiology of Isolated Clinic Normotension
Due to the relative recency of this body of literature, not much is known about the cause of isolated clinic normotension. On the one hand, it could be hypothesized that isolated clinic normotension is associated with an increased frequency of situations during daily life that are related to increased blood pressure (for example, increased smoking, physical activity, and stress); on the other hand, it is possible that isolated clinic normotensive patients adopt self-relaxing strategies during clinic visits that result in lower-than-actual clinic blood pressure determinations. At present, there is more evidence to support the former hypothesis.
For example, isolated clinic normotensives have been shown to exhibit poorer daily health habits than either essential hypertensive patients or normotensive controls. Several studies, for example, have found that isolated clinic normotensives were more likely to be past or current smokers than normotensives (Larkin et al., 1998a; Liu et al., 1999; Selenta et al., 2000; Wing et al., 2002). Two studies have shown that isolated clinic normotensives are more likely to be men rather than women as well as persons who consume alcohol (Larkin et al., 1998a; Selenta et al., 2000). Although no differences between isolated clinic normotensives and either hypertensive patients or normal blood pressure controls have emerged on measures of stress (Donner-Banzhoff et al., 1998), there is some indication that isolated clinic normotensives sleep less and engage in more physical activity during ambulatory monitoring periods than comparison groups (Larkin et al., 1998a).
One gets the picture that daily lives of isolated clinic normotensive patients are packed with work and home activities and that these patients may lack adaptive coping skills to deal with the number of activities in their lives. As such, they tend to adopt less adaptive coping strategies like smoking or drinking alcohol to deal with their daily emotional duress. At the current time, there is no evidence to suggest that isolated clinic normotensive patients adopt self-relaxing or self-soothing strategies while in the clinic; indeed, if they possessed such strategies, one would suspect they would use them outside of the clinic during their daily lives, which apparently they do not do.
Regardless of the specific behaviors involved in the etiology of isolated clinic normotension, the existence and pathology of the condition provide an important reason for considering broader applications of ambulatory blood pressure measurement. In fact, the most recent American Heart Association recommendations for measuring blood pressure advocates a more prominent role for ambulatory blood pressure monitoring in diagnosing cases of essential hypertension (Pickering et al., 2005).