How aldosterone, renin, the aldosterone-to-renin ratio, potassium, and kidney function help explain a hormonal cause of high blood pressure.
Primary aldosteronism (PA) is a disorder in which one or both adrenal glands produce aldosterone partly independently of the signals that normally control it. This can cause persistent high blood pressure, suppressed renin, and sometimes low potassium. A person can have PA even when potassium is normal and aldosterone is not flagged as high on the laboratory report.
The key screening question is whether aldosterone is inappropriately active while renin is suppressed. The aldosterone-to-renin ratio (ARR) helps reveal that relationship. Potassium, kidney function, medications, dietary sodium, collection conditions, and the laboratory method determine how confidently the result can be interpreted.
This guide explains how to connect those findings, when a result may need to be repeated, and what laboratory monitoring contributes after treatment. Screening can identify a pattern that deserves medical evaluation; it does not by itself identify which adrenal gland is responsible or determine whether surgery is appropriate.
Educational information only. A qualified healthcare professional should guide diagnosis, medication changes, suppression testing, and treatment. Do not stop blood-pressure medicines, change potassium supplements, or attempt salt-loading tests on your own.
For the broader evaluation after a high blood-pressure reading, start with Hypertension Lab Tests. This PA guide provides the detailed adrenal-hormone interpretation that supports that broader workup.
Related pillar guides include Endocrine Disorders: Causes, Symptoms, Lab Tests, and Management, Heart Health Blood Tests, and Kidney Function Tests. The Blood Biomarker Ratios Guide explains why a calculated ratio must be interpreted alongside its component measurements.
For testing fundamentals, preparation, and result interpretation, use The Complete Guide to Lab Tests and Blood Work, How to Read and Understand Your Lab Results, and Direct-Access Lab Testing: How It Works and What to Expect.
Aldosterone is a mineralocorticoid hormone produced by the adrenal cortex. It helps the kidneys regulate sodium and potassium and influences circulating volume and blood pressure. Renin is an enzyme released by the kidneys that helps activate the renin–angiotensin–aldosterone system.
When the body needs to conserve circulation, renin can rise and stimulate aldosterone production. When sodium retention expands circulating volume, renin normally falls and aldosterone should also decrease. In PA, aldosterone production is not appropriately suppressed. The kidneys retain sodium and water, blood pressure can rise, and potassium loss may develop.
In secondary hyperaldosteronism, aldosterone rises in response to activation of renin—for example, in some conditions that reduce effective kidney perfusion. Distinguishing these patterns requires both measurements and the clinical history.
PA is a potentially treatable cause of hypertension. Compared with primary hypertension, it is associated with greater cardiovascular and kidney risk. Recognizing aldosterone excess can lead to treatment directed at its hormonal mechanism, with surgery considered for suitable patients with disease localized to one gland and medication used for bilateral or nonsurgical disease.[1]
Kidney damage and cardiometabolic risk still deserve attention. The Albumin Random Urine Test with Creatinine (UACR) helps assess urine albumin leakage, while the Creatinine Test with eGFR provides filtration information. Depending on the person's history and prior results, an A1c Test and Lipid Panel Test can help assess coexisting glucose and cardiovascular risk. These tests do not confirm PA or prove that aldosterone caused a particular abnormality.
Detailed glucose, lipid, and general hypertension testing belongs within the broader Hypertension Lab Tests and Heart Health Blood Tests guides. Test selection should address the individual clinical question rather than expand automatically into a large panel.
The 2025 Endocrine Society guideline conditionally suggests screening all individuals with hypertension for PA. Implementation depends on resources, local expertise, and the capacity to interpret results and arrange follow-up. Screening measures aldosterone and renin, calculates the ARR, and checks potassium to support accurate interpretation.[1]
Clinical features that make a PA discussion especially relevant include:
These features help prioritize evaluation when broad screening is difficult. Their absence does not rule PA out. After a previously negative screen, worsening hypertension, new low potassium, or otherwise unexplained atrial fibrillation may justify reconsidering testing.
The Aldosterone and Plasma Renin Activity Ratio Test measures aldosterone and plasma renin activity and calculates their relationship. It is a focused starting option when screening is appropriate. Individual Aldosterone Test and Plasma Renin Activity Test measurements can also be used when a clinician needs them, but the interpretation must keep the two results connected.
Aldosterone indicates the hormone signal. Renin helps show whether that signal is appropriate for the body's regulatory state. Potassium affects aldosterone secretion and treatment safety. Kidney function can influence both the screening pattern and the safety of medications used to treat PA.
A high ARR alone is insufficient: the ratio can become large because renin is extremely low, even when aldosterone is not convincingly elevated. Review the actual aldosterone and renin concentrations, the ratio, the assay, and the clinical circumstances together.
The following examples use aldosterone in ng/dL and plasma renin activity (PRA) in ng/mL/hour. They illustrate the calculation and the importance of renin; they are not stand-alone diagnostic rules.
| Aldosterone | PRA | Calculated ARR | Interpretive question |
|---|---|---|---|
| 13 ng/dL | 0.2 ng/mL/hour | 65 | Why is aldosterone still present at this level when renin is strongly suppressed? |
| 13 ng/dL | 3.5 ng/mL/hour | About 3.7 | What is stimulating renin, and could medications or other conditions explain this pattern? |
The first pattern is more suggestive of renin-independent aldosterone activity under suitable testing conditions. The second does not show suppressed renin, but it cannot exclude PA without knowing the medication exposure, potassium, assay, and clinical probability.
The Endocrine Society provides guidance thresholds for common methods. A positive screen generally combines low renin, aldosterone that is inappropriately high, and an elevated ARR. No single cutoff is perfect, and the laboratory's validated decision limits should guide interpretation.[1]
The DRC ratio above 70 does not use aldosterone in ng/dL. PRA and DRC are different measurements and are not interchangeable. The guideline's ARR thresholds are approximately 25% lower for LC-MS/MS aldosterone than for immunoassay aldosterone. The Ulta combined test linked here lists an LC/MS/MS method and uses PRA, so the immunoassay examples should not be copied directly onto its report.
Many people with PA have potassium within the laboratory reference range. Waiting for low potassium can therefore miss cases. The Potassium Test supports screening interpretation and identifies an important safety issue, but potassium itself is not the PA screening test.
Low potassium can also suppress aldosterone secretion. A person with a high clinical likelihood of PA may consequently have a misleadingly low aldosterone result or a negative-looking screen. If hypokalemia could have affected a negative result, the clinician may arrange potassium correction into the reference range and repeat screening on another day.[1]
Marked potassium abnormalities deserve clinical attention in their own right. Do not delay care while waiting for another ARR, and do not change potassium supplements without guidance.
Choose tests according to their purpose: detecting the hormonal pattern, assessing kidney and electrolyte context, or evaluating a separate clinical concern. A metabolic panel already includes several individual measurements, so review its contents before ordering additional tests.
| Test | What it contributes | Important limitation |
|---|---|---|
| Aldosterone and Plasma Renin Activity Ratio Test | Aldosterone, PRA, and the calculated ratio in one order. | A positive pattern does not establish which adrenal gland is responsible. Medication effects, units, and collection conditions matter. |
| Aldosterone Test | The circulating aldosterone measurement when an individual assay is appropriate. | Interpret with renin. A result within the reference interval may still be inappropriate for a suppressed-renin state. |
| Plasma Renin Activity Test | Renin activity for paired interpretation or selected follow-up. | PRA differs from DRC. Medicines and kidney disease can change the result. |
| Potassium Test | Electrolyte status, support for aldosterone interpretation, and treatment-safety monitoring. | Normal potassium does not exclude PA; low potassium can reduce aldosterone secretion. |
| Test | When it can help | What it cannot establish |
|---|---|---|
| Basic Metabolic Panel Test (BMP) or Comprehensive Metabolic Panel Test (CMP) | Provides potassium, sodium, carbon dioxide/bicarbonate, glucose, and kidney-function information. The CMP also provides liver and protein measurements. | Neither panel diagnoses PA. A CMP is not automatically necessary when a narrower panel answers the question. |
| Creatinine Test with eGFR | Assesses kidney filtration and helps follow treatment safety. | One measurement does not explain the cause of a kidney change or establish chronicity. |
| Albumin Random Urine Test with Creatinine (UACR) | Assesses albumin leakage and kidney/cardiovascular risk in a person with hypertension. | Does not diagnose PA or prove that aldosterone caused the albuminuria. |
| Sodium Test | Provides electrolyte context when a separate measurement is appropriate. | Serum sodium does not measure dietary salt intake. |
| Magnesium Test | May help with selected symptoms, diuretic use, arrhythmia concerns, or difficult electrolyte correction. | Does not confirm or exclude PA. |
Autoimmune, inflammatory, liver, thyroid, anemia, and reproductive investigations should address separate symptoms or clinical questions. They should not be presented as a routine PA confirmation panel.
Current guidance favors morning collection with the person seated, potassium measured alongside aldosterone and renin, and avoidance of deliberate dietary sodium restriction during the preceding few days. The performing laboratory's collection protocol and the clinician's plan should be followed together.[1]
The linked Aldosterone and Plasma Renin Activity Ratio Test currently specifies a mid-morning draw, around 10 a.m., after at least two hours upright, followed by 5–15 minutes seated before collection. Confirm the current instructions when arranging the draw, especially if other tests are being collected at the same visit.
Blood-pressure medicines can affect renin and aldosterone in different directions. The Endocrine Society describes no-withdrawal and medication-withdrawal strategies because stopping treatment is not safe or necessary for every person. A clinician should choose the approach and interpret the result in that setting.[1]
Other medicines and exposures can also matter. The appropriate response to a potentially confounded result is to review the complete drug history and clinical probability, then decide whether repeat testing under a supervised plan would help. A ratio that changes after medication begins does not, by itself, show that PA appeared or disappeared.
A negative screen is more reassuring when potassium and collection conditions are appropriate, medication effects have been considered, and the clinical likelihood of PA is low. A repeat assessment may be useful when:
Chronic kidney disease adds another complication: it can alter both renin and aldosterone and increase false-positive screening patterns. Kidney disease should therefore inform interpretation rather than automatically be treated as evidence for PA.
Discuss whether the possible confounder can be corrected safely, whether another measurement would change management, and how the repeat sample should be collected.
A positive-looking screen begins a clinical decision process. An endocrinologist, hypertension specialist, nephrologist, or other experienced clinician considers the strength of the biochemical findings, the person's health, and whether surgery is a realistic option.
Saline infusion, oral sodium suppression, captopril challenge, and fludrocortisone suppression are examples of specialized approaches. These require defined protocols and clinical oversight; fluid or sodium loading can be unsafe in some people with severe hypertension, heart failure, or kidney disease.
The 2025 guideline does not require suppression testing after every positive ARR. It suggests testing particularly when the probability of disease arising predominantly from one adrenal gland is intermediate and the person wants to pursue eligibility for surgery. Testing may be bypassed when biochemical evidence is especially strong or when a person will pursue PA-specific medical treatment without a surgical workup.[1]
One example of strong biochemical evidence in the guideline combines resistant hypertension or hypertension with hypokalemia, PRA below 0.2 ng/mL/hour or DRC below 2 mU/L, and aldosterone above 20 ng/dL by immunoassay or above 15 ng/dL by LC-MS/MS. These are specialist decision criteria, not instructions for diagnosing yourself or skipping follow-up.
Adrenal CT shows anatomy, including nodules and other structural findings. A visible adrenal nodule does not prove that it produces aldosterone. Nonfunctioning nodules become more common with age, and aldosterone excess may arise from a gland without an obvious nodule.
For people considering adrenal surgery, CT and adrenal venous sampling (AVS) are generally used together. AVS compares hormone secretion from the adrenal glands to assess whether the excess is predominantly unilateral or bilateral. A limited exception may apply to selected patients younger than about 35 with marked PA, hypokalemia, and a clear unilateral adrenal adenoma larger than 1 cm, after specialist assessment.[1]
When aldosterone excess is localized to one gland, unilateral adrenalectomy may be appropriate. For bilateral disease or nonsurgical care, treatment generally uses a mineralocorticoid receptor antagonist (MRA). Correction of the hormonal disorder does not guarantee that all blood-pressure medication will become unnecessary.
When PA coexists with an adrenal adenoma, the Endocrine Society suggests a 1-mg overnight dexamethasone suppression test to assess possible autonomous cortisol secretion. Some adrenal lesions can contribute to more than one hormonal abnormality.[1]
In that clinician-directed protocol, prescribed dexamethasone is taken late at night and serum cortisol is measured the following morning. A post-dexamethasone cortisol above 1.8 µg/dL, or 50 nmol/L, suggests cortisol autonomy and warrants further endocrine evaluation. It does not establish the complete diagnosis by itself.
The Cortisol Total Test is a cortisol measurement, not the entire suppression test. Medication prescribing, timing, possible interfering medicines, specimen collection, and interpretation must be coordinated. A random cortisol result cannot substitute for this evaluation.
During MRA treatment, follow-up connects blood pressure, symptoms, potassium, kidney function, and renin. Spironolactone and eplerenone can raise potassium, and their safety depends partly on kidney function and concurrent medicines. Patients should not adjust the dose from one laboratory result.
Aldactone prescribing information calls for potassium monitoring within one week of starting or increasing treatment and regularly thereafter. More frequent monitoring may be needed with impaired kidney function or other medicines that increase potassium. Kidney function and volume status also require monitoring.[2]
Ask the prescribing clinician when to obtain the Potassium Test and kidney-function testing, whether a Basic Metabolic Panel Test (BMP) supplies the required measurements, and how results will be reviewed. Potassium supplements, potassium-containing salt substitutes, ACE inhibitors, ARBs, and some pain medicines can affect treatment safety.
Later follow-up assesses whether treatment is adequately controlling blood pressure and the effects of aldosterone excess. Renin can provide additional information about receptor blockade. A later review over the following weeks or months does not replace early potassium and kidney-safety monitoring.
When blood pressure remains uncontrolled and renin remains suppressed, the guideline suggests clinician-directed adjustment of PA-specific treatment to produce a rise in renin. It does not set one universal renin target. Evidence remains insufficient to justify increasing treatment solely to raise renin when blood pressure is already controlled. Medication effects and kidney function also affect interpretation.[1]
After adrenalectomy, the clinical team follows blood pressure, symptoms, potassium, kidney function, and medication requirements. Aldosterone and renin help assess biochemical response when measured at the appropriate stage of follow-up. Cortisol co-secretion may also affect postoperative adrenal assessment.
Untreated PA can cause glomerular hyperfiltration: pressure and flow through the kidney filters are higher than they would otherwise be. This can make the estimated glomerular filtration rate (eGFR) look better than the underlying kidney health warrants.
After adrenalectomy or effective medical treatment, hyperfiltration can decrease. Creatinine may rise and eGFR may fall as that effect reverses, sometimes revealing previously masked kidney impairment. Studies of treated PA support this explanation; it does not mean every decline is harmless or that kidney disease has been excluded.[3]
Clinical review should consider the size and persistence of the change, potassium, blood pressure, hydration, medications, and albuminuria. A marked or progressive decline, rising potassium, low urine output, fainting, or symptoms of dehydration requires prompt assessment. Do not assume that a worsening result is an expected treatment effect.
The Creatinine Test with eGFR and Albumin Random Urine Test with Creatinine (UACR) provide different information about filtration and albumin leakage. For a fuller explanation, see Kidney Function Tests.
These examples organize possible explanations. They do not replace assay-specific interpretation or establish a diagnosis from a single pattern.
| Result pattern | Possible explanation | Question for the clinician |
|---|---|---|
| Hypertension, normal potassium, suppressed renin, and aldosterone inappropriate for that renin level | PA remains possible despite normal potassium. | Does this meet the laboratory's screening criteria, and what follow-up is appropriate? |
| High clinical suspicion, low potassium, and a negative-looking screen | Hypokalemia may have lowered aldosterone. | Should potassium be corrected and screening repeated under a supervised plan? |
| High ARR, very low renin, and modest aldosterone while taking a beta blocker | Medication-related renin suppression may inflate the ratio. | Is the aldosterone value persuasive after considering the medicine and assay? |
| A previously abnormal ratio becomes lower after an MRA is started | Treatment can raise renin and alter the screening relationship. | Which findings should be used to assess response and safety now? |
| Confirmed PA with a unilateral adrenal nodule on CT | The nodule may or may not be the hormone-producing source. | Would AVS change the decision about surgery? |
| Blood pressure remains high and renin remains suppressed during MRA therapy | PA-specific treatment may need reassessment. | Can therapy be adjusted safely after reviewing potassium, kidney function, and medication use? |
| Blood pressure is controlled but renin remains suppressed | Renin alone does not establish a need for a higher dose. | What evidence supports a change, and would it improve outcomes safely? |
| Creatinine rises or eGFR falls after treatment | Reversal of hyperfiltration, medication effects, dehydration, or kidney injury may contribute. | Is the change stable and explainable, or does it require prompt investigation? |
Direct-access laboratory testing is not an emergency service. Call 911 for possible stroke or heart-attack symptoms. Blood pressure above 180 systolic and/or 120 diastolic together with chest pain, shortness of breath, new weakness or numbness, vision changes, or difficulty speaking requires emergency assessment. Do not wait for another laboratory result.[4]
If blood pressure remains above that range on a repeat measurement and there are no new concerning symptoms, contact a healthcare professional as soon as possible. Severe potassium abnormalities, marked muscle weakness, palpitations with an electrolyte abnormality, fainting, or rapidly worsening kidney function also need prompt clinical assessment.
Yes. A value within the general reference interval may still be inappropriate when renin is strongly suppressed. The absolute values, ratio, assay, potassium, medications, and clinical likelihood must be considered together.
No. A screening result does not establish laterality or surgical suitability. Follow-up depends on the strength of the evidence, the person's treatment preferences and health, and whether subtype testing would change management.
Do not stop them independently. A clinician can decide whether testing on the current regimen is interpretable or whether a supervised medication strategy is needed. Stopping treatment may create blood-pressure or electrolyte risks.
Not necessarily. Treatment can change both aldosterone and renin. Response is assessed using blood pressure, potassium, kidney function, symptoms, medication requirements, and appropriately selected hormone measurements.
No. The appropriate selection depends on whether the goal is screening, clarifying a result, assessing organ effects, or monitoring treatment. Avoid duplicating tests already included in a panel.
Bring your blood-pressure record, current medicines and supplements, prior aldosterone and renin reports, potassium, and kidney-function results to your clinician. Ask which clinical question the next test will answer and how you will receive follow-up if a result is abnormal.
Ulta Lab Tests offers the Aldosterone and Plasma Renin Activity Ratio Test, Potassium Test, and selected kidney and metabolic tests discussed above where available. For related options, explore High Blood Pressure Tests, Hormone Tests, Endocrine Tests, Kidney Tests, Kidney Health Tests, and Heart and Cardiovascular Tests.
For the broader testing plan around hypertension, continue with Hypertension Lab Tests.
Originally published: August 25, 2026 | Updated: September 10, 2026
| Category | Tests with embedded Ulta links |
|---|
| Primary aldosteronism screening | Aldosterone and Plasma Renin Activity Ratio Test |
| Individual hormone measurements | Aldosterone Test Plasma Renin Activity Test |
| Electrolyte interpretation and monitoring | Potassium Test Sodium Test Magnesium Test |
| Kidney function and metabolic panels | Basic Metabolic Panel Test (BMP) Comprehensive Metabolic Panel Test (CMP) Creatinine Test with eGFR |
| Urine albumin and kidney damage assessment | Albumin Random Urine Test with Creatinine |
| Additional adrenal evaluation when indicated | Cortisol Total Test |
| Cardiometabolic risk assessment | A1c Test Lipid Panel Test |
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