Secondary Hypertension
Secondary hypertension is high blood pressure (hypertension) caused by an identifiable underlying condition such as kidney disease, endocrine disorders, obstructive sleep apnoea, or medication use, and this article covers its causes, and when to suspect it.
Definition
Secondary hypertension refers to elevated blood pressure (hypertension) due to an identifiable underlying cause.
Causes
Most common causes: [Ref]
- Renal parenchymal diseases (e.g. diabetic nephropathy, hypertensive nephropathy, glomerulonephritis, polycystic kidney disease)
- Renovascular disease (e.g. atherosclerosis, fibromuscular dysplasia)
- Primary aldosteronism (Conn’s syndrome)
- Obstructive sleep apnoea
- Drug- or alcohol-induced: NSAIDs, oral contraceptives, steroids, sympathomimetics, cocaine/amphetamines, erythropoietin, VEGF inhibitors, calcineurin inhibitors (i.e., ciclosporin, tacroliumus)
Less common causes: [Ref]
- Coarctation of the aorta
- Cushing’s syndrome
- Phaeochromocytoma
- Hyperthyoiridsm
- Acromegaly
The most common overall cause is renal parenchymal causes. [Ref]
The most common cause in young adults (18-40 y/o) is primary aldosteronism (Conn’s syndrome). [Ref]
The ABCDE mnemonic is useful to recall the causes of secondary hypertension:
- A – Accuracy of diagnosis (white coat hypertension, improper cuff size) / Apnea (obstructive sleep apnea)
- B – Bruits (renal artery stenosis) / Bad kidneys (chronic kidney disease, nephropathy)
- C – Catecholamines (pheochromocytoma) / Cushing syndrome / Coarctation of the aorta
- D – Drugs (NSAIDs, OCPs, steroids, stimulants, decongestants) / Diet (excess sodium, alcohol, licorice)
- E – Endocrine (primary aldosteronism, thyroid disease, acromegaly) / Erythropoietin
When to Suspect
Secondary hypertension should be suspected in ANY of the following ‘red flags’: [Ref]
- Resistant hypertension (uncontrolled BP despite 3 antihypertensive agents)
- Hypertension in <30 y/o
- Abrupt onset or worsening of hypertension
- Specific clinical features suggest an underlying disorder (e.g. hypokalaemia, evidence of renal disease)
Related Articles
Nephrotic and Nephritic Syndromes
Obstructive Sleep Apnoea/Hypopnoea (OSAH) and Obesity Hypoventilation Syndrome (OHS)
Conn Syndrome (Primary Hyperaldosteronism)