Secondary hypertension is hypertension with an identifiable cause. It is usually refractory to medical treatment.
It is more frequent in young patients (< 30 years old) and older patients (> 65 years old) who first present with hypertension.
- Causes of Secondary Hypertension (7 Cs)
- Pheochromocytoma
- Cushing’s syndrome
- Conn’s syndrome (Hyperaldosteronism)
- Closing of the renal artery (renal artery stenosis)
- Contraceptives (COCPs)
- Congenital adrenal hyperplasia
- Coarctation of the aorta
- Pathogenesis of hypertension due to renal artery stenosis
- Narrowing leads to reduced renal blood flow → Increased renin secretion from the Juxtaglomerular apparatus → Renin converts angiotensinogen to angiotensin I in the lung→ Angiotensin I is converted to angiotensin II by ACE → Angiotensin II leads to an increase in the production of aldosterone from the adrenals
- → Aldosterone causes sodium and water retention. This raises cardiac output
- → Aldosterone is also a potent vasoconstrictor. It raises total peripheral resistance.
- Narrowing leads to reduced renal blood flow → Increased renin secretion from the Juxtaglomerular apparatus → Renin converts angiotensinogen to angiotensin I in the lung→ Angiotensin I is converted to angiotensin II by ACE → Angiotensin II leads to an increase in the production of aldosterone from the adrenals
Summary of causes of secondary hypertension
| Secondary cause | Symptoms | Diagnosis | Treatment |
|---|---|---|---|
| Pheochromocytoma | Pallor, Palpitations, Pain, Perspiration, Pressure | Urine vanillyl mandelic acid (VMA), Catecholamines, MNs; CT to localize the tumor | IV alpha-blocker, then a beta-blocker; Surgical resection of the tumor |
| Cushing’s disease | Weight gain, edema, hirsutism, buffalo hump, striae, weakness | U/E/C: Hypernatremia, Hypokalemia; 24-hr urine cortisol, Dexamethasone suppression test | Surgical resection of the tumor |
| Conn’s disease | Weakness, edema/weight gain | U/E/C: hypernatremia, hypokalemia; plasma aldosterone | Surgical resection of the tumor |
| Renal artery stenosis | Resistant hypertension, flank/renal bruit | Ultrasound; Renal arteriogram | Percutaneous transluminal angioplasty |
| Contraceptives | History of contraceptive use | Clinical diagnosis | Discontinue contraceptives; Intrauterine contraceptives or FP |
| Congenital adrenal hyperplasia | Hirsutism, masculinization | 17-OH progesterone levels | Fludrocortisone |
| Coarctation of the aorta | Uneven pulses, Pediatric hypertension, Systolic murmur, Neonatal symptoms | Chest X-ray | Surgical repair |