Blood pressure values that are slightly higher than that of 90% normal children are termed as “elevated blood pressure”. If the blood pressure is higher than levels found in 95% healthy children of the same sex and age, on three different occasions, the patient is considered to have “hypertension”. Based on the level of blood pressure compared to normal, hypertension is staged as stage 1 (mild) or stage II (severe). Children with stage II hypertension are at a higher risk of complications associated with high blood pressure. These children require urgent evaluation and management.
Hypertension in older children and adolescents, as in adults, may not have a precise cause and is termed “essential”. Essential hypertension is usually seen in older children, especially whose parent(s) also has/have high blood pressure. It may be associated with being overweight or obese, a sedentary lifestyle with reduced physical exercise, and excessive dietary intake of salt and carbohydrates.
In contrast, an underlying secondary cause is more likely in young children with high blood pressure. The younger the child, the more likely that high blood pressure is not “essential” but “secondary” to an underlying condition. The most common cause is in the kidneys; many forms of chronic and acute kidney diseases may present with hypertension. Other causes of secondary hypertension include narrowing of the aorta (coarctation) or of blood vessels supplying the kidneys (renovascular hypertension), diseases affecting the adrenal glands or the thyroid, and some medications.