Early Detection of BP Abnormalities by Ambulatory Monitoring in Normotensive Children With Predisposing Factors

Background: Measurements of the blood pressure is an essential part of the health care of children, as well as adults. Early elevation of the blood pressure is usually asymptomatic. However, if undetected, it may lead to progressive damage to target organs, including the heart and kidneys. For these reasons, it is an advantage to use a technique that allows the detection of increase blood pressure at the earliest possible time, to allow intervention before any effects of the blood pressure elevation on the target organs.
Objectives: This study was performed in order to find out if ambulatory blood pressure monitoring can detect early abnormalities in children who are considered normotensive by conventional blood pressure measurement, but who have one of the predisposing factors for the development of hypertension.
Methods: A group of 32 children (18 girls, 14 boys) (ages 8-15.5 years, mean 13) participated in the study. All participating children were normotensive by the usual method of measurement of blood pressure, and according to the normal levels for their age and gender. Twenty one of these children (9 girls, 12 boys) have a family history of hypertension (one or both parents with hypertension, currently under medication). 11 of these children (9 girls, 2 boys) have a history of one or more attacks of urinary tract infection. Mean 24-hr BP was evaluated in each of the two groups of children.
Results: Mean 24-hr BP ranged from 103 to 131 (mean =117 mm Hg) Systolic; and from 56 to 83 (mean = 72 mm Hg) Diastolic in the group of children with a family history of hypertension. Overall, 3/21 (14.3%) children in this group had mean 24-hr blood pressure, systolic and/or diastolic, exceeding their blood pressure taken by conventional measurement. Regarding the group of children with a history of UTI, mean 24-hr BP ranged from 110 to 136 (mean = 122 mm Hg) Systolic; and from 69 to 82 (mean = 78 mm Hg) Diastolic in this group of children. Overall, 2/11 (18.2%) children in this group had mean 24-hr blood pressure, systolic and/or diastolic, exceeding their blood pressure taken by conventional measurement. In addition, BP loads (% of readings =/˃ 95^th percentile, S & D) were evaluated in the two groups of children. BP loads ranged from 0% to 42.5% (mean = 15.4%) Systolic; and from 0% to 33.3% (mean = 12.9%)Diastolic in the group of children with a family history of hypertension.  Overall, 6/21 (28.5%) children in this group had blood pressure loads 20% or more (=20% or more of their blood pressure readings were greater than the 95^th percentile for age and sex), systolic and/or diastolic, day and/or night. Regarding the group of children with a history of UTI, BP loads ranged from 0% to 51% (mean = 22.5%) systolic; and from 0% to 29% (mean= 18.6%) Diastolic in this group of children. Overall, 4/11 (36.4%) children in this group had blood pressure loads 20% or more (= 20% or more of their blood pressure readings were greater than the 95^th percentile for age and sex), systolic and/or diastolic, day and/or night. In the group with a family history of hypertension, mean % nocturnal decline was 8.8% systolic and 11.9% diastolic. Overall, 0/21 of the children in this group showed absence of a drop of blood pressure during the night as compared to the day. In the group with a history of UTI, mean % nocturnal decline was 10.4% systolic and 13% diastolic. Overall, 1/11 of the children in this group showed absence of a drop of blood pressure during the night as compared to the day.
Conclusions: These data demonstrate that some early abnormalities of blood pressure can be detected by the use of ambulatory blood pressure monitoring in children who have one of the predisposing factors for hypertension. These abnormalities could not be detected by the use of conventional method of blood pressure measurement, which is done on one occasion. Such findings may help in the predication of blood pressure problems and its early management in predisposed children.