Assessing children's blood pressure--considerations of age and body size: the Muscatine Study.

Blood pressure was assessed in 4,207 children, aged 5 to 18 years, examined in the schools of Muscatine, Iowa during 1981. Overall, 69.9% of the age-sex-specific quintiles and height-sex-specific quintiles of systolic blood pressure were identical. In only 1.0% of children did these quintiles differ by more than one. Children whose blood pressure was in the highest quintile for both age and height were more obese than their peers. Those whose blood pressure was high for age but not for height were proportionately taller and heavier than their age peers. Children whose blood pressure was high for height but not for age were older, shorter, and lighter. Thus, having precocious levels of blood pressure for age during childhood is associated with excessive body weight or precocious height, whereas having high blood pressure for height but not for age is associated with being short for age. The latter suggests that age may be a factor independent of height and weight affecting blood pressure level in childhood. These relationships of body size and age to blood pressure must be considered when evaluating children's blood pressure levels in the clinical setting, and a technique for doing so is presented.