Hormone Panel

Aldosterone

The salt-and-water hormone that can quietly run high behind blood pressure no medication seems to fix.

Part of the Hormone Panel — see all 21 values together, including 17-Hydroxyprogesterone, Androstenedione, Calcitonin.

This hormone quietly decides how much salt and water the body keeps, and getting it wrong shows up as stubborn high blood pressure. Aldosterone is made by the adrenal glands, the two small glands that sit on top of the kidneys, and according to MedlinePlus its job is to balance sodium and potassium and, through them, blood pressure.

Think of it as the ballast control on a submarine. Aldosterone tells the kidneys when to take on more salt and water to hold pressure up, and when to dump them to let pressure fall. When the control works, the boat sits level. When it jams open and keeps taking on water, pressure climbs and stays there no matter what else you adjust.

That is what makes aldosterone an impostor among blood pressure problems. High blood pressure is usually treated as a fault in the heart and the vessels. But an estimated 5% to 14% of people with high blood pressure seen in primary care, and up to 30% of those seen at referral centers, actually have primary aldosteronism: a salt-retaining adrenal hormone running too high. The Endocrine Society describes it as a common, treatable cause that carries higher heart and kidney risk than ordinary hypertension at the same blood pressure, and in 2025 it recommended that everyone diagnosed with hypertension have their aldosterone, renin, and potassium levels checked.

Why aldosterone is never read alone

A single aldosterone number tells you very little by itself. The level rises when you stand, falls when you lie down, and drops when you eat a lot of salt, so the same person can produce different results on different mornings. MedlinePlus notes the test is usually paired with a renin test as the aldosterone-renin ratio, used to find out whether too much aldosterone is driving blood pressure up and whether the problem sits in the adrenal glands or somewhere else.

Renin is the kidney's pressure signal. When blood pressure or volume drops, renin rises and tells aldosterone to hold on to salt; when pressure is fine, renin quiets down and aldosterone should ease off with it. Normally the two move together. The fingerprint of primary aldosteronism is aldosterone that stays high while renin is pushed down to almost nothing, the ballast control acting on its own and ignoring the signal. The Endocrine Society's diagnostic pattern is elevated aldosterone production together with suppressed renin.

This is the part consumer pages tend to bury: a result that looks normal can still be the abnormal finding. An aldosterone sitting in the upper part of its reference range can be entirely inappropriate when renin is suppressed, because the body should have throttled it down and did not. Reading the two numbers as a pair is the whole reason the test earns its place.

How aldosterone reads against renin

Primary aldosteronism: the control jammed open

Aldosterone Renin · suppressed Potassium · low or normal

Aldosterone high while renin is suppressed is the pattern the Endocrine Society uses to flag primary aldosteronism. Potassium is often low but can be normal, so a normal potassium does not rule it out.

Normal-looking aldosterone, suppressed renin

Aldosterone Renin · suppressed

The quiet version of the same problem. An in-range aldosterone can still be inappropriate when renin is flat, which is why the ratio matters more than either number alone.

Secondary aldosteronism: responding to a real signal

Aldosterone Renin

When both rise together, aldosterone is reacting to something else pulling on the kidney's pressure signal rather than running the show itself.

Adrenal insufficiency: the control stuck shut

Aldosterone Potassium

Low aldosterone with high potassium and low blood pressure points toward the adrenal glands underproducing, the opposite failure from the one behind resistant hypertension.

What does high aldosterone mean?

High aldosterone is the side of this test that matters most, because it is the side that hides inside everyday high blood pressure. MedlinePlus describes the excess pattern, hyperaldosteronism, as high blood pressure with low potassium or high sodium, often alongside muscle weakness, fatigue, and increased thirst and urination. People living it describe blood pressure that won't come down no matter how many meds they try, potassium that keeps dropping, and the leg cramps and weakness that low potassium brings.

The test is most often ordered for exactly these situations: high blood pressure that occurs with low potassium, or high blood pressure that does not respond to the usual medicines, what clinicians call resistant hypertension. The reason it is worth chasing is the risk on the other side of a missed diagnosis. The Endocrine Society notes that untreated primary aldosteronism raises the risk of stroke, coronary artery disease, atrial fibrillation, heart failure, and kidney disease beyond what the blood pressure number alone would predict.

What can push aldosterone high

  • A problem in the adrenal glands themselves

    Primary aldosteronism, where one gland or both overproduce. Subtyping after a positive screen sorts out which, because it changes treatment.

  • A genuine drop in pressure or volume the kidney is correcting

    Here renin rises too, so aldosterone is following orders rather than giving them, and reading the two together tells them apart.

  • Posture and a low-salt sample

    Standing and salt restriction both lift the number, which is why prep is controlled before the draw.

What does low aldosterone mean?

Low aldosterone is the rarer direction, and it shows up as the mirror image of the high-pressure story. MedlinePlus links it to adrenal insufficiency, where the glands underproduce, and to low blood pressure with high potassium. Instead of holding on to too much salt and water, the body sheds them, and pressure sags. Because sodium and potassium sit at the heart of what aldosterone controls, they are usually checked in the same draw and read together. Aldosterone is also a close relative of cortisol, the other major adrenal hormone, so a doctor weighing adrenal insufficiency often looks at both.

Getting an aldosterone test that means something

  1. 1

    Start with the doctor who ordered it

    Ask how the sample should be taken and whether any of your medicines need adjusting first, since several blood pressure drugs shift the result.

  2. 2

    Know that posture and salt move the number

    Aldosterone runs higher upright and lower lying down, and salt suppresses it, so the conditions of the draw are part of the result.

  3. 3

    Expect renin and potassium on the same order

    The aldosterone-renin ratio is the screen the Endocrine Society relies on; a lone aldosterone value is hard to act on.

  4. 4

    Treat a positive screen as a starting point

    The Endocrine Society follows a positive ratio with confirmatory testing (saline infusion, oral salt loading, fludrocortisone suppression, or a captopril challenge) before any diagnosis is settled.

Aldosterone in context

Aldosterone is one piece of the adrenal and pressure-regulating system, which is why it travels with renin, potassium, sodium, and cortisol rather than standing alone. On a broader workup it sits inside the hormone panel, and the logic of reading it against its partners is laid out in the guide to reading a hormone panel. If you take one thing from this page, let it be that a normal aldosterone is not automatically a reassuring one: paired with a suppressed renin, an unremarkable number can be the clue that explains years of blood pressure that never quite came down.

Sources

Written and reviewed by BloodSight Editorial Team · Last updated

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Normal ranges

Group Range Unit
Adult Male 4–31 ng/dL
Adult Female 4–31 ng/dL

Reference ranges may vary by laboratory and individual factors.

Aldosterone — Common Questions

Why is aldosterone tested together with renin instead of on its own?
A single aldosterone number swings with posture, salt intake, and time of day, so it means little in isolation. MedlinePlus notes the test is usually paired with renin as the aldosterone-renin ratio. Renin is the kidney's pressure signal, and the ratio shows whether aldosterone is responding to that signal or ignoring it, which is the difference between an ordinary result and a sign of an adrenal problem.
My aldosterone is in the normal range but my renin is suppressed. Is that a problem?
It can be. The Endocrine Society's diagnostic pattern for primary aldosteronism is aldosterone production that is too high relative to renin, where renin is suppressed. A level sitting inside the reference range can still be inappropriate if renin has been pushed down to almost nothing, because the body should have throttled aldosterone back and did not. This is a finding to review with your doctor rather than read off the page alone.
Can high aldosterone be why my blood pressure won't come down on medication?
Yes, and it is more common than most people expect. The Endocrine Society estimates that 5% to 14% of high blood pressure seen in primary care, and up to 30% seen at referral centers, is primary aldosteronism. MedlinePlus lists blood pressure that does not improve with usual medicines, especially alongside low potassium, as a reason to order the test.
Does posture or salt intake change the result?
Both do. Aldosterone runs higher when you are upright and lower when lying down, and salt loading suppresses it. Because of this, labs and clinicians control how the sample is drawn, and your doctor may adjust certain medications beforehand. The exact prep matters enough that the result should be interpreted by the team who ordered it.
I have high blood pressure and low potassium. Should I be tested for primary aldosteronism?
That combination is the classic pattern MedlinePlus describes for excess aldosterone, and it is a common reason the test is ordered. The 2025 Endocrine Society guidance goes further and suggests checking aldosterone, renin, and potassium in everyone diagnosed with hypertension. Whether to test is a conversation to have with your doctor.
If I have primary aldosteronism, is it treatable?
It is one of the few clearly treatable causes of high blood pressure, which is why the Endocrine Society pushes for screening. A positive screen is followed by confirmatory testing and then subtyping to find out whether one adrenal gland or both are involved, because that distinction guides treatment. The specifics are a discussion for an endocrinologist.

Disclaimer

This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendation. Reference ranges may vary by laboratory. Always discuss your results with a qualified healthcare professional.

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