Why a Clinician May Check Aldosterone When Reviewing High Blood Pressure

Why Aldosterone Is Checked When Blood Pressure Stays High

When a clinician reviews high blood pressure, the question is not only how high the numbers are but whether something specific is driving them. Aldosterone is one of the things worth ruling in or out. It is a hormone made by the adrenal glands, two small glands that sit above the kidneys, and it helps keep blood pressure stable by balancing sodium and potassium in the blood. Sodium helps the body hold more water in the bloodstream, which raises blood pressure, while potassium helps blood vessels relax and helps the kidneys clear excess sodium. When blood pressure runs low, aldosterone signals the kidneys to keep more sodium and release potassium, which brings pressure back up; when pressure returns to normal, aldosterone levels fall.^[source]

That normal feedback loop can go wrong. In primary aldosteronism, the adrenal glands produce excess aldosterone that is at least partly independent of renin, the system's normal regulator, and renin levels are suppressed. The extra aldosterone leads to sodium retention, volume expansion, elevated blood pressure, and in more severe forms low potassium. The Endocrine Society's 2025 guideline notes that people with primary aldosteronism face significantly higher health risks than people with primary hypertension, and that the condition remains largely underdiagnosed and undertreated.^[source]

The important limit is this: a high blood pressure reading on its own does not show a hormonal cause. Most high blood pressure is not primary aldosteronism. What follows explains the reasoning a clinician may use when requesting an aldosterone check, not a personal test order for any reader.

What the 2025 Guideline Suggests About Screening

A common assumption is that only people with low potassium or hard-to-control blood pressure are screened. The 2025 Endocrine Society guideline takes a broader view. It suggests screening for primary aldosteronism in all individuals with hypertension, but this is a conditional recommendation: implementation depends on contextual factors such as available resources, local expertise, and health system capacity, which can affect feasibility and prioritization. In other words, it is a considered suggestion rather than a universal mandate, and it is not an instruction to any individual reader.^[source]

Screening itself is specific. It means measuring serum or plasma aldosterone concentration together with plasma renin, either concentration or activity, and determining the aldosterone-to-renin ratio. Potassium is also measured, but not as the screening test; it is there to help interpret aldosterone accurately.^[source]

Why Low Potassium or Resistant Hypertension Still Raises the Question

If screening is suggested broadly, why does a clinician still focus on potassium or on blood pressure that will not come down? Because those findings change how much weight to place on a result. In primary aldosteronism, excess aldosterone can cause hypokalemia in more severe forms, and low potassium can lead to a falsely low aldosterone result. That is why potassium is measured alongside renin and aldosterone, and why the guideline advises correcting potassium to within the laboratory reference range and repeating screening when an initial result is negative in someone with hypokalemia.^[source]

Resistant hypertension and hypokalemia are described as factors that raise pretest probability and may prompt repeat testing. They are not the only reasons a clinician considers screening, and they are not the sole screening population.^[source]

How Home Blood Pressure Readings Fit Into the Conversation

Home readings are often treated as if they could reveal a cause. They cannot. What a home log can do is document the pattern and persistence of elevated blood pressure over time, which is context a clinician may weigh alongside office readings. It cannot identify a hormonal cause, replace aldosterone and renin testing, or confirm a diagnosis. A log supports the discussion; it does not substitute for clinical assessment.^[source]

Bring the blood pressure record you already keep, together with your medicine list and the instructions for this test. Ask your clinician which parts of that record are useful for your assessment. A record-preparation routine is separate from deciding whether hormone testing is needed.

What the Aldosterone and Renin Tests Measure

An aldosterone test measures the amount of aldosterone in blood or urine. Renin is an enzyme made by the kidneys; when blood pressure or sodium decreases or potassium increases, the kidneys release renin, which controls the production of aldosterone. Because the two work together, an aldosterone test is often done at the same time as a renin test, reported as an aldosterone-renin ratio.^{[source][source]}

Both hormones vary. Levels are highest in the morning and change through the day, and body position, stress level, and certain medicines can affect renin and aldosterone results. That is why results are interpreted together with other information rather than in isolation.^[source]

Why Timing, Position, and Medicines Affect the Result

The clinic's interest in when you test, whether you are seated, and which medicines you take is not bureaucracy. The guideline's technical remarks describe morning sampling with the person seated, and note that aldosterone and renin are influenced by body position, stress, and medicines, including diuretics, mineralocorticoid receptor antagonists, ACE inhibitors, angiotensin receptor blockers, beta-blockers, and centrally acting agents.^[source]

The guideline outlines both minimal-withdrawal and no-withdrawal strategies for interfering medicines, chosen according to individual safety and feasibility, and some results may need to be repeated on a different day. Do not stop or change any prescribed medicine on your own. Follow the instructions of the team that ordered the test.^[source]

Confirming Preparation With the Ordering Team

Preparation for aldosterone screening is individualized, so the most useful step is to ask the ordering team directly. General sodium-restriction or licorice-avoidance advice found online is not a universal rule for primary aldosteronism screening, and the ordering team's instructions take precedence.^{[source][source]}

What Happens After a Screening Result

A positive screen is a first step, not a diagnosis. The guideline describes further evaluation, such as aldosterone-suppression testing in selected situations, and adrenal imaging with adrenal venous sampling when surgery is being considered. A negative screen may be repeated when factors such as hypokalemia or interfering medicines could have caused a false negative. Repeat screening may also be considered later if hypertension worsens, new hypokalemia appears, or atrial fibrillation occurs without another explanation. These are the steps clinicians consider, not a plan for any individual reader.^[source]

Why a Hormonal Cause Is Worth Identifying

The guideline describes primary aldosteronism as an adrenal disorder that remains underdiagnosed and undertreated. It suggests that subsequent care be guided by screening results and discusses PA-specific medical or surgical options. Ask your clinician what the findings would change about the next step in your assessment.^[source]

Where This Article Stops

This is general education about why a clinician may check aldosterone. It does not diagnose primary aldosteronism, does not tell anyone whether to be tested, does not provide a preparation protocol, and does not interpret individual results. Discuss your own readings, medicines, and results with your care team. Urgent symptoms need appropriate urgent care rather than this article.^[source]

Frequently Asked Questions

Does high blood pressure always mean I have an aldosterone problem?

No. Most high blood pressure is not caused by primary aldosteronism. The 2025 guideline conditionally suggests screening in all individuals with hypertension because the disorder is underdiagnosed, but a screening suggestion is not a diagnosis, and a high reading alone does not show a hormonal cause.

Will my home blood pressure readings replace the aldosterone and renin test?

No. Home readings can document the pattern and persistence of elevated blood pressure, which a clinician may weigh alongside office readings, but they cannot detect a hormonal cause or substitute for aldosterone and renin measurement. A log is discussion support only.

Should I stop my blood pressure medicine before the test?

Do not stop or change any prescribed medicine on your own. The guideline describes both minimal-withdrawal and no-withdrawal strategies for interfering medicines depending on individual safety and feasibility, and the ordering team decides what applies. Ask your care team directly.

Should I cut back on salt before an aldosterone test?

Do not adopt generic online diet instructions as a rule. The guideline technical remarks describe avoiding dietary sodium restriction in the few days before screening, but patient education sources may describe different preparation for other test purposes. The ordering team's instructions for the specific test take precedence.

What does a positive screening result mean?

A positive screen is a first step rather than a diagnosis. The guideline describes further evaluation, such as aldosterone-suppression testing in selected situations and adrenal imaging with adrenal venous sampling when surgery is being considered. Only the treating clinician can interpret an individual result.

Can a negative result be wrong?

The guideline notes that factors such as hypokalemia or interfering medicines can lead to a falsely negative result, and that repeat testing on a different day may be suggested in those situations. Re-screening may also be considered later if hypertension worsens, new hypokalemia appears, or atrial fibrillation occurs without another explanation.

Is aldosterone testing the same as a potassium test?

No. Potassium is measured alongside aldosterone and renin to aid accurate interpretation of aldosterone, not as the screening test itself. The screen is aldosterone plus renin with the aldosterone-to-renin ratio, and low potassium can make aldosterone appear falsely low.

Where can I read more about the tests themselves?

MedlinePlus describes what the aldosterone and renin tests measure and why results are considered with other information, and the Endocrine Society publishes the 2025 guideline recommendation language. These are educational sources, not a personal test order or preparation protocol.