Understanding Essential (Primary) Hypertension
Essential hypertension, also known as primary hypertension, is high blood pressure with no identifiable cause, accounting for approximately 95% of all hypertension cases. 1, 2
Definition and Prevalence
Essential hypertension is characterized by:
- Persistently elevated blood pressure (≥140/90 mmHg) without an identifiable secondary cause
- Accounts for 90-95% of all hypertension cases
- Affects approximately 20% of adults worldwide 3
- In industrialized countries, lifetime risk of developing hypertension exceeds 90% 2
Pathophysiology
Essential hypertension results from complex interactions between:
Genetic Factors
- Polygenic disorder with multiple genes influencing blood pressure
- More than 25 rare mutations and 120 single nucleotide polymorphisms identified
- Collective effect of identified loci represents only about 3.5% of blood pressure variability 4
Environmental Factors
- High sodium, low potassium/calcium/magnesium diet
- Obesity and overweight
- Physical inactivity
- Excessive alcohol consumption
- Psychosocial stress 4
Physiological Mechanisms
- Endothelial dysfunction with impaired production of vasodilators (nitric oxide, prostacyclin)
- Overexpression of vasoconstrictors (thromboxane A2, endothelin-1)
- Vascular remodeling affecting all layers of blood vessel walls
- Increased peripheral vascular resistance
- Neurohormonal activation 4
Diagnosis
Essential hypertension is diagnosed when:
- Blood pressure readings are consistently ≥140/90 mmHg on multiple occasions
- Secondary causes of hypertension have been ruled out
Important diagnostic considerations:
- White-coat hypertension should be excluded through 24-hour ambulatory blood pressure monitoring (ABPM) or home BP monitoring 3
- Normal values for 24-hour ABPM before 22 weeks of pregnancy: 24-hour average <126/76 mmHg; awake average <132/79 mmHg; sleep average <114/66 mmHg 3
Distinguishing from Secondary Hypertension
Secondary hypertension (5-10% of cases) has identifiable causes such as:
- Renal parenchymal disease
- Renal artery stenosis
- Primary aldosteronism (prevalence ~20% in resistant hypertension) 3
- Obstructive sleep apnea (very common in resistant hypertension) 3
- Pheochromocytoma (rare, 0.2-0.4% of hypertension cases) 3
- Other endocrine disorders (Cushing's syndrome, hyperparathyroidism) 3
Complications of Untreated Essential Hypertension
Persistent elevated blood pressure leads to target organ damage:
- Heart: Left ventricular hypertrophy, heart failure, coronary artery disease
- Brain: Stroke, cognitive decline, dementia
- Kidneys: Chronic kidney disease with decreased glomerular filtration rate
- Blood vessels: Macro and microangiopathy
- Eyes: Hypertensive retinopathy 4
In severe cases, untreated hypertension can progress to malignant hypertension, a hypertensive emergency characterized by very high blood pressure with advanced retinopathy, acute renal failure, and/or thrombotic microangiopathy 3.
Management Approach
Management of essential hypertension requires:
- Therapeutic lifestyle modifications (cornerstone of treatment)
- Pharmacotherapy (often multiple medications)
- Regular monitoring and follow-up
The principal drug classes recommended as initial pharmacotherapy include:
- Thiazide-type diuretics
- Calcium channel blockers
- ACE inhibitors or angiotensin receptor blockers 5
Key Takeaways
- Essential hypertension is a diagnosis of exclusion after ruling out secondary causes
- It results from complex interactions between genetic predisposition and environmental factors
- Early diagnosis and treatment are crucial to prevent target organ damage
- Management requires both lifestyle modifications and often pharmacotherapy
- Regular monitoring is essential for optimal blood pressure control