What labwork should be ordered for an 18-year-old male with hypertension?

Laboratory Workup for an 18-Year-Old Male with Elevated Blood Pressure

For an 18-year-old male with elevated blood pressure, order a comprehensive metabolic panel (including fasting glucose, sodium, potassium, calcium, and creatinine with eGFR), complete blood count, lipid profile, thyroid-stimulating hormone, urinalysis with urine albumin-to-creatinine ratio, and a 12-lead electrocardiogram. 1

Basic Laboratory Testing (Required for All Patients)

The 2017 ACC/AHA guidelines specify that laboratory measurements should be obtained for all patients with a new diagnosis of hypertension to facilitate cardiovascular risk profiling, establish baseline values before medication use, and screen for secondary causes of hypertension. 1

Blood Tests

• Fasting blood glucose to identify diabetes mellitus, which significantly increases cardiovascular risk and lowers treatment thresholds 1, 2
• Complete blood count to detect anemia or other hematologic abnormalities 1
• Lipid profile for cardiovascular risk stratification 1, 2
• Serum creatinine with estimated glomerular filtration rate (eGFR) to assess kidney function and detect chronic kidney disease 1
• Serum sodium, potassium, and calcium (typically included in comprehensive metabolic panel) to detect electrolyte abnormalities that may suggest secondary causes like primary aldosteronism 1
• Thyroid-stimulating hormone to easily detect hypothyroidism and hyperthyroidism, both remediable causes of hypertension 1

Urine Tests

• Urinalysis to screen for kidney disease 1
• Urinary albumin-to-creatinine ratio rather than urine dipstick, as it is more sensitive for detecting early kidney damage and cardiovascular risk 1, 2

Cardiac Testing

• 12-lead electrocardiogram to detect left ventricular hypertrophy, arrhythmias (including atrial fibrillation), and ischemic heart disease 1, 2

Special Considerations for Young Adults (Age ≤30 Years)

For adults ≤30 years of age with elevated brachial blood pressure, a thigh blood pressure measurement is indicated; if the thigh measurement is lower than arm pressures, coarctation of the aorta should be considered. 1

Young patients with hypertension warrant heightened suspicion for secondary causes, particularly given the absence of typical risk factors like obesity, family history, or gradual onset. 1, 3

Screening for Secondary Hypertension

In an 18-year-old male, secondary causes of hypertension are more likely than in older adults. 3 Clinical clues suggesting secondary hypertension include:

• Age of onset <30 years 3
• Severe or resistant hypertension 3
• Absence of family history of hypertension 1
• Abrupt onset rather than gradual increase 1, 3

Key Laboratory Findings That Suggest Secondary Causes

• Hypokalemia suggests primary aldosteronism or renovascular disease 1
• Elevated creatinine or reduced eGFR suggests renal parenchymal disease or renovascular disease 1, 2
• Proteinuria or albuminuria indicates kidney damage 2

The 2024 ESC guidelines now recommend measuring renin and aldosterone in all adults with confirmed hypertension, representing a significant change from traditional approaches. 3 This is particularly relevant for young patients where primary aldosteronism affects 8-20% of resistant hypertension cases. 3

Optional Testing

Optional tests may provide information on target organ damage and should be considered based on clinical presentation: 1

• Echocardiogram if ECG shows abnormalities, cardiac symptoms are present, or detection of left ventricular hypertrophy would influence treatment decisions 1, 2
• Uric acid 1

Clinical Pitfalls to Avoid

• Do not use urine dipstick alone for albuminuria screening; use urine albumin-to-creatinine ratio instead, as it is more sensitive for detecting early kidney damage 1
• Do not skip the ECG; it is essential for detecting left ventricular hypertrophy and arrhythmias even in young patients 1
• Do not overlook secondary causes in young patients; the prevalence is higher than in older adults with gradual-onset hypertension 3
• Confirm hypertension with repeated measurements before extensive workup, but do not delay basic laboratory testing once hypertension is confirmed 1
• In African American populations with asymptomatic elevated blood pressure, there is a relatively high prevalence of abnormalities on basic metabolic panel that may lead to hospital admission, making routine testing particularly important 4

Monitoring During Treatment

Once treatment is initiated, monitoring of serum sodium and potassium levels is helpful during diuretic or renin-angiotensin system blocker titration, as are serum creatinine and urinary albumin as markers of chronic kidney disease progression. 1, 5