Causes of Hypertensive Emergency
Hypertensive emergency is caused by several conditions that lead to severely elevated blood pressure with acute target organ damage, including medication non-compliance, endocrine disorders, renal disease, pregnancy complications, and substance use.
Definition of Hypertensive Emergency
Hypertensive emergency is defined as substantially elevated blood pressure with acute hypertension-mediated organ damage (HMOD) affecting target organs including the retina, brain, heart, large arteries, and kidneys 1. Key characteristics:
- Requires rapid diagnostic workup and immediate BP reduction to prevent progressive organ failure 1
- Usually requires intravenous therapy 1
- The choice of antihypertensive treatment is determined by the type of organ damage 1
- No specific BP threshold defines a hypertensive emergency, though values commonly exceed 200/120 mmHg 1
Primary Causes of Hypertensive Emergency
Medication-Related Causes
- Non-adherence with prescribed antihypertensive drugs 1, 2
- Inadequate antihypertensive therapy 2
- Withdrawal from antihypertensive medications 3
- Drug interactions (e.g., tyramine-containing foods with monoamine oxidase inhibitors) 3, 4
Substance-Related Causes
- Recreational drugs (cocaine, methamphetamine) 1, 5
- Sympathomimetics 1
- Anabolic steroids 1
- Some herbal remedies 1
Endocrine Causes
Renal Causes
- Renovascular hypertension 3
- Acute glomerulonephritis 3
- Renal artery stenosis 1
- Chronic kidney disease 1
Pregnancy-Related Causes
- Severe preeclampsia 1
- Eclampsia 1, 4
- HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) 1
Neurological Causes
Cardiovascular Causes
Other Causes
Clinical Presentations of Hypertensive Emergency
Malignant Hypertension
- Severe BP elevation (commonly >200/120 mmHg) 1
- Advanced bilateral retinopathy (hemorrhages, cotton wool spots, papilledema) 1
- May present with or without thrombotic microangiopathy (TMA) 1
Hypertensive Encephalopathy
- Severe BP elevation with neurological manifestations 1
- Symptoms include lethargy, seizures, cortical blindness, coma 1
- Occurs in absence of other explanations 1
Hypertensive Thrombotic Microangiopathy
- Severe BP elevation with hemolysis and thrombocytopenia 1
- Improvement with BP-lowering therapy 1
- Characterized by Coombs-negative hemolysis 1
Other Presentations
- Cerebral hemorrhage 1
- Acute stroke 1
- Acute coronary syndrome 1
- Cardiogenic pulmonary edema 1
- Aortic aneurysm/dissection 1
- Acute renal failure 1
Risk Factors for Developing Hypertensive Emergency
- Pre-existing hypertension 1
- Cardiac disease 1
- Chronic renal disease 1
- Non-Hispanic black population 1
- Low socioeconomic status 1
- Use of uterocontractive drugs 1
Important Clinical Considerations
- Secondary causes can be found in 20-40% of patients presenting with malignant hypertension 1
- The severity of hypertensive crisis is determined not by the absolute BP level but by the magnitude of the acute increase 2
- In patients with normally low baseline BP (such as in eclampsia), even systolic BP >170 mmHg may lead to life-threatening conditions 2
- Patients with substantially elevated BP who lack acute HMOD are not considered to have a hypertensive emergency 1
Diagnostic Approach
Thorough evaluation includes:
- Medical history focusing on preexisting hypertension, symptom onset, and potential causes 1
- Physical examination with cardiovascular and neurologic assessment 1
- Laboratory analysis including hemoglobin, platelets, creatinine, electrolytes, LDH, haptoglobin, and urinalysis 1
- Fundoscopy to assess for retinopathy 1
- ECG to evaluate cardiac involvement 1
- Additional investigations based on clinical presentation (e.g., cardiac troponins, chest x-ray, echocardiogram, brain imaging) 1