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Health condition

Aldosteronism (Conn’s)

Primary aldosteronism (Conn’s syndrome) is the most common curable cause of high blood pressure - and it is massively underdiagnosed.

Key points

What matters most, at a glance.

The essentials in plain English - symptoms, when to seek help, who to see and what treatment looks like.

  • Affects perhaps 5-10% of people with hypertension, most of whom are never tested

  • Suspect it with resistant hypertension, low potassium, or high blood pressure under 40

  • Screening is a blood test: the aldosterone-to-renin ratio

  • Caused by an adrenal nodule (removable surgically) or both glands overworking (treated with spironolactone)

  • An endocrinologist confirms the diagnosis and steers treatment

Understanding it

About Aldosteronism (Conn’s), and what to do next.

In primary aldosteronism, the adrenal glands autonomously overproduce aldosterone, forcing the kidneys to retain salt and lose potassium. The result is stubborn high blood pressure that responds poorly to standard tablets, sometimes with fatigue, muscle cramps or low potassium on routine bloods. Because it also damages the heart and kidneys beyond the blood pressure itself, finding it matters.

Screening is a simple ratio blood test, confirmed with suppression testing and adrenal imaging; adrenal vein sampling distinguishes a one-sided nodule from bilateral disease. Removing a unilateral nodule can cure the condition, while bilateral disease responds well to targeted medication such as spironolactone. Most people start with their GP, who can refer to an endocrinologist. NHS routine referrals often take 20-45+ weeks depending on where you live, while a private consultation is typically available within about two weeks.

A quiet reminder

This guide is for information, not medical advice.

Your GP knows your history and can tell you which parts apply to you. If in doubt, see them.

Frequently asked

Common questions about Aldosteronism (Conn’s).

Quick, plain-English answers to what people ask us most.

  • What is aldosteronism (Conn's syndrome)?

    Conn's syndrome, or primary aldosteronism, is a condition where the adrenal glands produce too much aldosterone, a hormone that regulates salt and water balance, leading to high blood pressure and low potassium levels.

  • What causes Conn's syndrome?

    It is most commonly caused by a benign tumour (adenoma) on one adrenal gland, or by overactivity of both adrenal glands (bilateral hyperplasia), both leading to excess aldosterone production.

  • What are the symptoms of Conn's syndrome?

    Symptoms include high blood pressure that can be difficult to control with standard medications, muscle weakness or cramps, and sometimes excessive thirst and urination from low potassium levels.

  • Is Conn's syndrome dangerous?

    Yes, if untreated, the persistently high blood pressure significantly increases the risk of stroke, heart disease, and kidney damage, more so than similar blood pressure levels from other causes.

  • Can Conn's syndrome be cured?

    Yes, if caused by a tumour on one adrenal gland, surgical removal of that gland can cure the condition; if both glands are involved, medication can very effectively control it long-term.

  • How is Conn's syndrome treated?

    Treatment depends on the cause: unilateral tumours are typically treated with surgical removal of the affected adrenal gland, while bilateral disease is usually managed with specific blood-pressure medications called mineralocorticoid receptor antagonists.

  • How is Conn's syndrome diagnosed?

    Diagnosis involves blood tests measuring aldosterone and renin levels, confirmatory testing, and imaging or specialised adrenal venous sampling to determine whether one or both adrenal glands are involved.

  • Conn's syndrome vs essential (primary) hypertension — what's the difference?

    Essential hypertension is high blood pressure without an identifiable specific cause, while Conn's syndrome is a specific, treatable hormonal cause of high blood pressure, often suspected when blood pressure is difficult to control or accompanied by low potassium levels.

  • How long does it take to see improvement after treatment?

    Blood pressure often improves substantially within weeks of starting appropriate medication or after successful surgery, though some patients continue to need blood pressure medication even after treatment, albeit often at lower doses.

  • When should I see a doctor about possible Conn's syndrome, and how quickly can I be seen privately?

    See a doctor if you have difficult-to-control high blood pressure or low potassium levels. NHS endocrinology referral can take 20 to 45 or more weeks, while private specialist assessment is often available within about two weeks.