What blood work and initial treatment are indicated in a hypertensive emergency?

Blood Work in Hypertensive Emergency

Obtain a comprehensive laboratory panel immediately including hemoglobin, platelets, creatinine, sodium, potassium, LDH, haptoglobin, quantitative urinalysis for protein, and urine sediment examination for erythrocytes, leukocytes, cylinders and casts. 1

Essential Laboratory Tests

The diagnostic workup must focus on detecting acute hypertension-mediated organ damage across multiple systems:

Core Laboratory Panel

• Complete blood count: Hemoglobin and platelet count to assess for microangiopathic hemolytic anemia and thrombocytopenia, which indicate thrombotic microangiopathy 1, 2
• Renal function: Creatinine, sodium, and potassium to evaluate for acute kidney injury 1, 2
• Hemolysis markers: LDH and haptoglobin to detect hemolysis in hypertensive thrombotic microangiopathy 1, 2
• Urinalysis: Quantitative protein measurement and urine sediment examination for erythrocytes, leukocytes, cylinders and casts to identify renal damage 1, 2

Additional Tests Based on Clinical Presentation

• Cardiac markers: Troponin-T, CK, CK-MB if chest pain is present to evaluate for acute coronary syndrome 1, 2
• Peripheral blood smear: For assessment of schistocytes when thrombotic microangiopathy is suspected 1, 2

Diagnostic Examinations

Beyond laboratory work, the following are essential:

• ECG: To detect ischemia, arrhythmias, or left ventricular hypertrophy 1, 2
• Fundoscopy: Should be performed when malignant hypertension is suspected to identify retinal hemorrhages, cotton wool spots, and papilledema 1, 2

Conditional Studies

• Chest X-ray or point-of-care ultrasound: For suspected fluid overload or pulmonary edema 1
• Transthoracic echocardiography: To assess cardiac structure and function 1
• CT or MRI brain: If intracranial hemorrhage or hypertensive encephalopathy is suspected 1
• CT-angiography of thorax and abdomen: For suspected acute aortic disease 1
• Renal ultrasound: To evaluate for postrenal obstruction, kidney size, or left-to-right differences 1

Initial Treatment Approach

Admit immediately to an intensive care unit for continuous blood pressure monitoring and initiate parenteral antihypertensive therapy. 1, 2

Blood Pressure Targets

• Standard approach: Reduce mean arterial pressure by 20-25% within the first hour, then if stable reduce to 160/100 mmHg over 2-6 hours, then cautiously normalize over 24-48 hours 1, 2
• Aortic dissection exception: Target systolic BP <120 mmHg and heart rate <60 bpm immediately 2
• Acute coronary syndrome: Target systolic BP <140 mmHg immediately 2

First-Line IV Medications

• Nicardipine: 5 mg/hr initially, titrate by 2.5 mg/hr every 15 minutes to maximum 15 mg/hr 2, 3
• Labetalol: 0.25-0.5 mg/kg IV bolus or 2-4 mg/min continuous infusion 2
• Clevidipine: 1-2 mg/hr initially, doubling every 90 seconds until BP approaches target 2

Critical Pitfalls to Avoid

• Do not reduce BP to normal acutely: Patients with chronic hypertension have altered cerebral autoregulation and cannot tolerate acute normalization—this can precipitate cerebral, renal, or coronary ischemia 1, 2
• Avoid excessive drops >70 mmHg systolic: This may cause acute renal injury and early neurological deterioration 1, 2
• Do not delay laboratory testing: Immediate assessment is crucial for appropriate management 2
• Recognize that BP may fall spontaneously: Repeated measurements should be performed over time, as BP will fall considerably without medication in a significant proportion of patients 1
• Focus on rate of BP rise, not absolute value: The rate of BP increase is more important than the absolute BP value in development of hypertensive emergencies 1

Post-Stabilization Considerations

After initial stabilization, screen for secondary causes of hypertension (found in 20-40% of malignant hypertension cases), including renal artery stenosis, pheochromocytoma, and primary aldosteronism 2. Address medication non-adherence, the most common trigger for hypertensive emergencies 2.