What laboratory tests are recommended for a patient in hypertensive crisis?

Laboratory Tests for Hypertensive Crisis (206/117 mmHg)

For a patient with blood pressure of 206/117 mmHg, a comprehensive laboratory workup is essential to assess for target organ damage and should include serum creatinine, eGFR, urine albumin-to-creatinine ratio, complete blood count, electrolytes, and cardiac biomarkers.

Initial Assessment and Classification

First, it's important to determine whether this represents a hypertensive emergency or urgency:

• Hypertensive Emergency: BP >180/120 mmHg WITH evidence of new or worsening target organ damage
• Hypertensive Urgency: BP >180/120 mmHg WITHOUT evidence of target organ damage 1

Essential Laboratory Tests

Basic Laboratory Panel

• Serum creatinine and eGFR: To assess kidney function and detect acute kidney injury 2
• Urine albumin-to-creatinine ratio (ACR): More sensitive than standard dipstick for detecting early kidney damage 2
• Electrolytes (sodium, potassium): To identify electrolyte abnormalities that may contribute to or result from hypertension 1
• Complete blood count: To assess for anemia or evidence of microangiopathic hemolytic anemia 1
• Blood glucose: To identify diabetes or stress hyperglycemia 1

Additional Tests Based on Suspected Target Organ Damage

• Cardiac biomarkers (troponin): If chest pain or suspected acute coronary syndrome 1
• Brain natriuretic peptide (BNP): If suspected heart failure or pulmonary edema
• Liver function tests: Especially with suspected HELLP syndrome or liver involvement
• Lactate dehydrogenase (LDH) and haptoglobin: To assess for hemolysis in thrombotic microangiopathy 1
• Urinalysis: For protein, blood, and sediment examination 1

Diagnostic Tests Beyond Laboratory Work

• 12-lead ECG: Recommended for all hypertensive patients to assess for left ventricular hypertrophy or acute ischemic changes 1
• Fundoscopic examination: Critical for detecting hypertensive retinopathy (flame-shaped hemorrhages, cotton wool spots, papilledema) which defines malignant hypertension 1
• Chest X-ray: If pulmonary symptoms are present to assess for pulmonary edema 1
• Brain imaging (CT/MRI): If neurological symptoms are present 1
• Echocardiography: If cardiac symptoms or abnormal ECG findings 1

Special Considerations

• Thrombotic microangiopathy (TMA): In severe hypertension with evidence of hemolysis, check schistocytes on peripheral smear, LDH, haptoglobin, and platelet count 1
• Secondary hypertension workup: Consider if clinical presentation suggests an underlying cause (e.g., pheochromocytoma, primary aldosteronism, renal artery stenosis) 1

Clinical Pitfalls to Avoid

1. Don't delay testing: Laboratory assessment should be performed promptly in patients with severe hypertension to determine appropriate management 1

2. Don't miss malignant hypertension: Always perform fundoscopy in patients with BP >180/110 mmHg to detect retinopathy 1

3. Don't overlook subtle organ damage: Microalbuminuria can be present before overt proteinuria and indicates early kidney damage 2

4. Don't rely solely on a single BP reading: Confirm elevated readings, but don't delay workup when BP is severely elevated 1

5. Don't forget to repeat testing: If moderate-to-severe CKD is diagnosed, measurements of serum creatinine, eGFR, and urine ACR should be repeated at least annually 1

By following this comprehensive laboratory assessment approach, clinicians can quickly identify target organ damage, determine whether the patient has a hypertensive emergency requiring immediate intervention, and guide appropriate treatment decisions.