Causes of Elevated Blood Pressure (Hypertension)
Primary Hypertension
Primary (essential) hypertension accounts for approximately 90-95% of all hypertension cases and is caused by a complex interplay of genetic and environmental factors. 1
Key Risk Factors for Primary Hypertension:
Lifestyle factors:
- Weight gain/obesity (particularly central obesity)
- High sodium diet (excessive salt intake)
- Physical inactivity
- Excessive alcohol consumption (>2 drinks/day for men, >1 drink/day for women)
- Poor diet (low in fruits, vegetables, and potassium)
- Tobacco use
- Job changes requiring increased travel
- Stress
Non-modifiable factors:
- Family history of hypertension
- Advanced age
- Genetic predisposition
- Race/ethnicity (higher prevalence in Black individuals)
Secondary Hypertension
Secondary hypertension (5-10% of cases) results from an identifiable underlying condition. Key causes include:
Renal Causes:
- Chronic kidney disease
- Renovascular disease (renal artery stenosis)
- Polycystic kidney disease
- Post-renal urinary tract obstruction
Endocrine Causes:
- Primary aldosteronism (prevalence up to 20% in resistant hypertension) 1
- Cushing's syndrome (characterized by central obesity, facial rounding, easy bruisability)
- Pheochromocytoma (presenting with BP lability, episodic pallor, dizziness)
- Thyroid disorders (hyperthyroidism with weight loss, palpitations, heat intolerance)
- Hyperparathyroidism
Sleep Disorders:
- Obstructive sleep apnea (characterized by snoring, hypersomnolence) 1
Vascular Causes:
- Coarctation of the aorta (history of repair with residual hypertension)
- Aortic disease
Medication and Substance-Induced Hypertension: 2
- NSAIDs (can increase BP by 3-5 mmHg)
- Oral contraceptives (can increase BP by 6/3 mmHg)
- Decongestants (phenylephrine, pseudoephedrine)
- Stimulants (amphetamines, cocaine, methamphetamine)
- Corticosteroids
- Immunosuppressants (cyclosporine)
- Erythropoietin
- Antidepressants (particularly tricyclics and SNRIs)
- Licorice (contains glycyrrhizic acid which has mineralocorticoid effects)
- Alcohol
- Herbal supplements (Ma Huang/ephedra, yohimbine, high-dose ginseng)
Clinical Clues Suggesting Secondary Hypertension 1
- Onset of hypertension before age 30
- Abrupt onset of hypertension
- Previously well-controlled BP that becomes difficult to control
- Resistant hypertension (requiring ≥3 medications including a diuretic)
- Accelerated/malignant hypertension
- Presence of target organ damage disproportionate to BP level
- Specific symptoms suggesting secondary causes
- Absence of family history of hypertension
- Hypokalemia without diuretic use
Diagnostic Approach
Basic laboratory tests for all patients with hypertension should include: 1
- Fasting blood glucose
- Complete blood count
- Lipid profile
- Serum creatinine with eGFR
- Serum electrolytes (sodium, potassium, calcium)
- Thyroid-stimulating hormone
- Urinalysis
- Electrocardiogram
Additional testing should be guided by clinical suspicion of specific secondary causes.
Prevention and Management Considerations
The management of hypertension should focus on addressing modifiable risk factors: 1
- Weight loss for overweight/obese individuals
- Adoption of DASH diet (Dietary Approaches to Stop Hypertension)
- Sodium reduction
- Increased potassium intake (preferably through diet)
- Regular physical activity (structured exercise program)
- Limiting alcohol consumption
- Avoiding medications and substances that can elevate BP
When pharmacological treatment is indicated, first-line medications include thiazide diuretics, calcium channel blockers, ACE inhibitors, and angiotensin receptor blockers. 1
For patients with suspected medication or substance-induced hypertension, discontinuation or substitution of the offending agent should be considered when possible. 2
Common Pitfalls in Hypertension Diagnosis
- Failure to recognize white coat hypertension or masked hypertension
- Not considering secondary causes in appropriate clinical scenarios
- Overlooking medication and substance use that can elevate BP
- Inadequate BP measurement technique
- Not recognizing the importance of lifestyle factors in BP control
Understanding the multifactorial nature of hypertension is essential for effective prevention, diagnosis, and management of this common but serious condition.