In a 13-year-old obese boy with persistent hypertension and acanthosis nigricans, what is the next step to confirm the diagnosis of hypertension?

Ambulatory Blood Pressure Monitoring (ABPM) is the Next Step

In this 13-year-old obese boy with persistent hypertension documented on multiple visits, ambulatory blood pressure monitoring (ABPM) is the next step to confirm the diagnosis of true hypertension versus white coat hypertension before proceeding with extensive secondary hypertension workup. 1

Rationale for ABPM First

Diagnostic Confirmation Priority

• The 2017 American Academy of Pediatrics guidelines specifically recommend ABPM to confirm the diagnosis of hypertension in children and adolescents with repeatedly elevated office BP readings before initiating extensive workup or treatment. 1
• ABPM is cost-effective because it identifies white coat hypertension, which occurs in up to 50% of children with elevated office readings, thereby preventing unnecessary diagnostic testing and treatment in these patients. 1, 2
• The pediatric guidelines emphasize that diagnosis of hypertension requires demonstration of elevated BP at 3 separate encounters, and ABPM provides superior diagnostic accuracy by capturing multiple readings in the patient's natural environment. 1, 2

Clinical Context of This Patient

• This 13-year-old meets the threshold for using adult BP definitions (≥130/80 mmHg for hypertension), making ABPM particularly valuable for confirming sustained hypertension versus episodic elevations. 1
• The presence of obesity and acanthosis nigricans suggests insulin resistance and metabolic syndrome, which are associated with primary (essential) hypertension rather than secondary causes requiring immediate imaging. 3, 4, 5
• Acanthosis nigricans in an obese adolescent strongly indicates obesity-associated hypertension with metabolic syndrome, where confirming true hypertension takes precedence over searching for rare secondary causes. 4, 5

Why Not Renal Ultrasound or Catecholamines First

Renal Ultrasound Timing

• Renal ultrasound is specifically recommended for children <6 years of age as part of routine evaluation, not for adolescents ≥13 years. 1
• In obese adolescents with acanthosis nigricans, the pretest probability of renal parenchymal disease or renovascular disease is low compared to primary hypertension. 3, 6
• Guidelines recommend evaluation for secondary hypertension "based on clinical and laboratory findings" after confirming true hypertension, not as the initial diagnostic step. 1

Catecholamine Testing Inappropriateness

• Screening for pheochromocytoma with catecholamines or metanephrines is reserved for patients with specific clinical features (paroxysmal symptoms, severe/resistant hypertension, family history) or after basic evaluation suggests this diagnosis. 1
• The clinical presentation of obesity with acanthosis nigricans does not suggest pheochromocytoma, making this an inappropriate initial test. 1

Algorithmic Approach After ABPM

If ABPM Confirms Hypertension

• Proceed with basic laboratory evaluation: metabolic panel (electrolytes, glucose, creatinine), lipid profile, urinalysis, hemoglobin A1c, and liver function tests (specifically recommended for obese children). 1
• Consider renal ultrasound only if laboratory findings suggest renal disease (elevated creatinine, abnormal urinalysis) or if hypertension is severe/resistant to treatment. 1
• Initiate lifestyle modifications immediately (weight reduction, dietary changes, increased physical activity) as primary treatment for obesity-associated hypertension. 3, 6

If ABPM Shows White Coat Hypertension

• Avoid extensive secondary hypertension workup and medication initiation. 1, 2
• Focus on lifestyle interventions and annual BP monitoring, as white coat hypertension does not require the same aggressive evaluation or treatment. 1, 2

Common Pitfalls to Avoid

• Do not skip ABPM and proceed directly to imaging or specialized testing, as this leads to unnecessary costs and potential harm from false-positive findings in patients with white coat hypertension. 1, 2
• Do not assume all hypertension in obese adolescents is primary—but confirm true hypertension first before extensive secondary workup. 6, 7
• Do not order renal ultrasound reflexively in adolescents ≥13 years without specific clinical indicators, as guidelines reserve this for younger children (<6 years) or when clinical findings suggest renal disease. 1