Secondary Hypertension, Child

Make the Diagnosis: Does This Child with High Blood Pressure Have Secondary Hypertension?

Prior Probability of Secondary Hypertension

Hypertension affects 4% of children and 11% of adolescents.¹ The thresholds that affect blood pressure vary by age, height, and sex. For children aged 1 to 12 years old, an elevated blood pressure is defined as ≥ 90th percentile to < 95th percentile or 120/80 mm Hg to <95th percentile (whichever is lower). For children 13 years of age or older, an elevated blood pressure is greater than 120/80 mm Hg. To confirm the diagnosis of hypertension, 24-hour ambulatory blood pressure monitoring is recommended.¹

Primary hypertension is an elevated blood pressure in a seemingly healthy child or adolescent that is not associated with a clear underlying cause, whereas secondary hypertension is caused by another medical condition, other than obesity. In primary care clinics or school-based screening programs, the prevalence of secondary hypertension among those identified with an elevated blood pressure is around 9%.^2-4 Among children referred by their pediatrician to specialty clinics for evaluation of elevated blood pressure, the prevalence of secondary hypertension is 44%.⁵

Population Among Whom Secondary Hypertension Should Be Considered

All children with hypertension should be evaluated to determine whether they have secondary hypertension. Affected children should have a urinalysis, serum electrolytes, blood urea nitrogen, serum creatinine, and a lipid panel. Children younger than 6 years of age should have a kidney ultrasound. Children and adolescents with obesity should have a hemoglobin A1c, serum aspartate transaminase and alanine transaminase. Other tests may be indicated depending on the clinical history and initial studies, such as fasting serum glucose, thyroid-stimulating hormone, drug screening, sleep studies, complete blood count, plasma renin activity, aldosterone level, plasma and urine catecholamines, and renovascular imaging.

Assessing the Likelihood That the Patient Has Secondary Hypertension

While the child or adolescent with hypertension should be classified as having elevated blood pressure, stage 1 hypertension, or stage 2 hypertension (with thresholds based on age and gender), the degree of hypertension, sex, and race do not identify those more or less likely to have secondary hypertension. A family history of secondary hypertension or a child that is of low body weight are more likely to have secondary hypertension (see Table 112-1). In studies that did not identify whether a family history of hypertension was due to primary or secondary causes, the presence of any family history of hypertension lowers the likelihood of secondary hypertension in the affected child. Children who are obese may still have secondary hypertension, but it is more likely that they have primary hypertension. Of children who are diagnosed with secondary hypertension, 77% may be attributable to kidney or renovascular disease (Supplemental Table 3).