Conn Syndrome (Primary Aldosteronism)
Excess aldosterone causing high blood pressure
Quick Facts
- Type: Hormone (endocrine) disorder
- Hormone involved: Aldosterone (from the adrenal glands)
- Main effect: High blood pressure
- Sometimes causes: Low blood potassium
Overview
Conn syndrome, also called primary aldosteronism, is a hormone disorder in which the adrenal glands (small glands that sit on top of the kidneys) produce too much of a hormone called aldosterone. Aldosterone normally helps the body balance sodium, potassium, and fluid, which in turn affects blood pressure. When too much is produced, the body holds onto sodium and water and loses potassium, leading to high blood pressure.
Conn syndrome is an important and underrecognized cause of high blood pressure, particularly blood pressure that is difficult to control with usual medications. Identifying it matters because it can often be treated specifically, and untreated excess aldosterone can harm the heart, blood vessels, and kidneys.
Symptoms
Many people have no specific symptoms beyond high blood pressure. When symptoms occur, they often relate to high blood pressure or low potassium:
- High blood pressure, sometimes severe or hard to control
- Headache
- Muscle weakness, cramps, or spasms (from low potassium)
- Fatigue
- Increased thirst and frequent urination
- Numbness or tingling
Because symptoms can be vague or absent, Conn syndrome is often found during evaluation of unexplained or treatment-resistant high blood pressure, or low potassium found on blood tests.
Causes
Conn syndrome results from one or both adrenal glands producing excess aldosterone. The two most common causes are:
- Adrenal adenoma: A benign (noncancerous) tumor in one adrenal gland that makes aldosterone.
- Bilateral adrenal hyperplasia: Both adrenal glands are enlarged and overactive.
Less common causes include rare inherited forms and, very rarely, an adrenal cancer. Distinguishing between a single tumor and overactivity of both glands is important because it changes the treatment.
Risk Factors
- High blood pressure that is severe or resistant to several medications
- High blood pressure together with unexplained low potassium
- High blood pressure at a younger age
- A family history of early high blood pressure or stroke
- An adrenal mass found on imaging done for other reasons
Diagnosis
Diagnosis usually begins with blood tests that measure the levels of aldosterone and renin (a kidney enzyme) and compare them. A high aldosterone with low renin suggests Conn syndrome. Confirmatory tests may follow to verify that aldosterone is being produced inappropriately.
If the diagnosis is confirmed, imaging such as a CT scan of the adrenal glands helps look for a tumor. A specialized procedure called adrenal vein sampling may be used to determine whether one or both glands are responsible, which guides whether surgery is appropriate.
Treatment
Treatment depends on whether one or both adrenal glands are overactive:
- Surgery: If a single adrenal gland (usually with a benign tumor) is the source, removing that gland can cure or greatly improve the high blood pressure.
- Medication: If both glands are overactive, or surgery is not suitable, medications that block aldosterone's effects (mineralocorticoid receptor antagonists) lower blood pressure and correct potassium.
- Blood pressure management: Additional blood pressure medicines and a lower-sodium diet may be recommended.
Treatment also aims to protect the heart, kidneys, and blood vessels from long-term harm.
When to See a Doctor
See a doctor if you have high blood pressure that is hard to control despite several medications, high blood pressure at a young age, or high blood pressure together with low potassium. Testing for Conn syndrome may be appropriate.
Seek urgent care for very severe headache, chest pain, vision changes, shortness of breath, or signs of a stroke (sudden weakness, facial drooping, or difficulty speaking), which can occur with dangerously high blood pressure. Severe muscle weakness or an irregular heartbeat from very low potassium also needs prompt evaluation.
Frequently Asked Questions
What does aldosterone do in the body?
Aldosterone is a hormone from the adrenal glands that helps balance sodium, potassium, and fluid. In Conn syndrome, too much aldosterone causes the body to retain sodium and water and lose potassium, which raises blood pressure.
Why is Conn syndrome important to diagnose?
It is a treatable cause of high blood pressure, often one that resists usual medications. Identifying it allows specific treatment, and correcting excess aldosterone helps protect the heart, blood vessels, and kidneys from long-term damage.
Can Conn syndrome be cured?
When the cause is a single overactive adrenal gland, removing that gland with surgery can cure or greatly improve the high blood pressure. When both glands are overactive, it is managed effectively with medications that block aldosterone.
How is Conn syndrome diagnosed?
It usually starts with blood tests comparing aldosterone and renin levels, followed by confirmatory testing. Imaging of the adrenal glands and sometimes adrenal vein sampling are used to find the source and guide treatment.
Does Conn syndrome always cause low potassium?
No. Low potassium is a classic finding but does not occur in everyone. Many people have normal potassium, so the condition can be missed if testing relies only on potassium levels rather than on aldosterone and renin.
References
- MedlinePlus, U.S. National Library of Medicine. Primary aldosteronism.
- Mayo Clinic. Primary aldosteronism — Symptoms and causes.
- The Endocrine Society.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).