Should labs be drawn on a patient with acute hypertension?

Laboratory Testing in Acute Hypertension

Yes, laboratory tests should be drawn on patients with acute high blood pressure to assess for target organ damage and identify potential underlying causes. 1

Initial Laboratory Evaluation

The International Society of Hypertension and European Society of Cardiology guidelines recommend the following essential laboratory tests for patients presenting with acute hypertension:

Basic Blood Tests (Required)

• Sodium and potassium (to identify electrolyte abnormalities and screen for primary aldosteronism) 1
• Serum creatinine and estimated glomerular filtration rate (eGFR) (to assess kidney function) 1
• Fasting glucose (to screen for diabetes) 1
• Lipid profile (to assess cardiovascular risk) 1

Urinalysis (Required)

• Dipstick urinalysis (to detect proteinuria, hematuria) 1
• Urinary albumin-to-creatinine ratio (to detect microalbuminuria) 1

Electrocardiogram (Required)

• 12-lead ECG to detect atrial fibrillation, left ventricular hypertrophy, or ischemic heart disease 1

Clinical Decision Algorithm

1. For all patients with BP ≥140/90 mmHg: Obtain basic labs (sodium, potassium, creatinine, eGFR, glucose, lipids) and urinalysis 1

2. For patients with BP ≥180/110 mmHg:

   • Perform immediate assessment for target organ damage
   • Add hemoglobin, platelets, LDH, haptoglobin to evaluate for possible microangiopathic hemolysis 1

3. For patients with signs/symptoms of hypertensive emergency:

   • Add cardiac troponins (if chest pain or dyspnea)
   • Consider liver function tests
   • Obtain more specialized tests based on presenting symptoms 1

Rationale for Laboratory Testing

Laboratory tests are crucial in acute hypertension for several reasons:

1. Identifying target organ damage: More than 50% of hypertensive patients have additional cardiovascular risk factors that can be detected through laboratory testing 1

2. Detecting secondary causes: Laboratory abnormalities may reveal underlying causes such as primary aldosteronism (hypokalemia), renal disease (elevated creatinine), or endocrine disorders 1, 2

3. Risk stratification: Laboratory findings help determine cardiovascular risk and guide treatment decisions 1

4. Distinguishing hypertensive urgency from emergency: Laboratory tests help differentiate between patients requiring immediate intervention versus those who can be managed less aggressively 1, 3

Common Pitfalls to Avoid

• Failing to check for target organ damage: Patients with severe hypertension may have silent organ damage despite minimal symptoms 1, 4

• Overlooking electrolyte abnormalities: Hypokalemia may indicate primary aldosteronism, a potentially treatable cause of hypertension 1, 2

• Neglecting kidney function assessment: Renal impairment affects both prognosis and treatment choices 1

• Treating based on BP numbers alone: Laboratory findings should guide the urgency and approach to treatment, not just BP values 1

• Missing microalbuminuria: An early marker of kidney damage that significantly impacts cardiovascular risk assessment 1

Special Considerations

• Pregnant patients: Additional testing for preeclampsia markers is essential 1

• Young patients with severe hypertension: More extensive workup for secondary causes is warranted 2

• Elderly patients: Interpretation of results should consider age-related changes in laboratory values 1

Laboratory testing in acute hypertension is not just diagnostic but guides treatment decisions and helps prevent progression to hypertension-mediated organ damage, ultimately improving morbidity, mortality, and quality of life outcomes.