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The prevalence and rate of diagnosis of hypertension in children and adolescents are increasing. Childhood hypertension may also lead to adult hypertension. Origins of the problem have been proposed to arise from fetal and early life. Although these prevalence rates can be determined from a single measurement, hypertension management and prevention strategies are dependent on incidence rates and disease progression.1
The diagnosis of hypertension in children is complicated because normal and abnormal blood pressure values in children are a function of age, sex and height percentile. Keeping electronic medical records from an early age may be helpful, though, in addition, it is necessary to track the medical history of parents and children. Children and adolescents with stage 1 or stage 2 hypertension should include additional evaluation of plasma rennin activity, imaging of the renal vasculature and plasma of urine steroid and catecholamine levels as well as a complete blood count, creatinine, electrolytes, fasting lipid panel, renal ultrasound and echocardiogram.2
Essential hypertension is rarely found in children younger than 10 years, and risk factors include family history and increased body mass index, sleep apnoea and metabolic syndrome. Secondary hypertension is more common in children, and renal disease is the most common cause. Transient rise in blood pressure, which can be mistaken for hypertension, is seen with caffeine, anxiety and stress.3
Obarzanek and colleagues have conducted a cohort study in 2368 girls (49% Caucasian, 51% African American) aged 9 or 10 years to estimate the prevalence and incidence of hypertension by measuring blood pressure, height and weight at annual visits through age 18–19 years.
On the basis of two visits, the hypertension prevalence was 1–2% in African American girls and 0.5% in Caucasian girls. The incidence in 8 years was 5% and 2.1%, respectively. The authors also found that obese girls had higher prevalence and incidence rates compared to girls with normal blood pressure. Body mass index and lower potassium intake were found independently associated with an incidence of hypertension.
Even though this paper gives useful information about the prevalence of hypertension and incidence in girls, it lacks supportive data about the medical history of family and children especially at younger ages.
Were these children normotensive a few years ago? Have they been breast-fed? Were they taking any medications? At what age did they become obese? This is of great importance since obesity is a strong risk factor of hypertension. If these children were obese at age 5 or 6, they possibly had hypertension from that age. Thus, blood pressure should be checked routinely at every visit in children 3 years of age and older.2
Another limitation of the study was the authors' failure to evaluate in the 8-year follow-up period on possible laboratory tests which aimed at revealing the cause and target organ consequences of elevated blood pressure.4 Moreover, the risk prediction of cardiovascular disease, stroke or organ damage for these children is of great importance for the development of appropriate guidelines.
Finally, the authors should examine possible criteria to use for the identification of undiagnosed rates of hypertension, since physicians are more likely to look carefully for elevated blood pressure in obese children.5 Stressing the importance of identifying elevated blood pressure in children meeting prehypertension or hypertension criteria is important, but if abnormal blood pressure is not identified by a patient's paediatric clinician it may take years to be detected and organ damage may occur.
While the estimation of prevalence and incidence of hypertension over a period of time may be useful, the use of patient medical history as well as additional medical examinations are necessary in order to have a clear picture of the problem, and lead, in turn, to the construction of appropriate prevention strategies.
Competing interests None.
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