The diagnostic workup for hyperaldosteronism, more specifically primary aldosteronism, follows a structured sequence: screening with the aldosterone-to-renin ratio, confirmation with a suppression test, and then subtype differentiation to determine whether surgery is an option. Each step has its own pitfalls, and the process can take weeks to months depending on how smoothly the testing goes. What makes this workup unusual compared to other endocrine evaluations is how much your current medications, body position, and even the lab’s choice of assay can skew results at every stage.
Who Gets Tested and Why It Matters
Primary aldosteronism was once thought to be a rare curiosity, responsible for maybe one percent of hypertension cases. That estimate has climbed substantially as screening has become more common, though exactly how high the true prevalence goes remains debated. Among people with resistant hypertension (blood pressure that stays elevated despite three or more medications), rates are clearly elevated, though one large retrospective study argued the prevalence was still lower than some of the more dramatic estimates circulating in the literature.1PubMed. Prevalence of primary hyperaldosteronism in resistant hypertension: a retrospective observational study Some experts now argue that the answer to “who should we screen?” is straightforward: everyone with hypertension.2PubMed. Who and How Should We Screen for Primary Aldosteronism?
In practice, most clinicians focus screening on higher-risk groups: people whose blood pressure resists multiple drugs, anyone with unexplained low potassium, those with an adrenal mass found incidentally on imaging, and patients with early-onset or severe hypertension. But the push toward universal screening reflects a growing recognition that primary aldosteronism causes cardiovascular damage out of proportion to the blood pressure numbers alone, meaning delayed diagnosis carries real consequences.
The Screening Step
Screening relies on the aldosterone-to-renin ratio, or ARR. The idea is simple: in primary aldosteronism, the adrenal glands pump out aldosterone autonomously, which suppresses renin. A high aldosterone paired with a low renin produces an elevated ratio, flagging the patient for further testing. There are two ways to measure the renin side of this equation: plasma renin activity (PRA), the traditional method, and direct renin concentration (DRC), a newer automated approach that is faster and more convenient for labs.
Both versions of the ratio perform reasonably well. A meta-analysis of the DRC-based ratio found pooled sensitivity around 87% and specificity around 85% for detecting primary aldosteronism, diagnostic accuracy at least comparable to the older PRA-based approach.3PubMed Central. Aldosterone/direct renin concentration ratio as a screening test for primary aldosteronism: a systematic review and meta-analysis Another study found that the two ratios correlate well with each other and that both achieve sensitivity above 80% and strong specificity at certain thresholds.4PubMed. The ratios of aldosterone / plasma renin activity (ARR) versus aldosterone / direct renin concentration (ADRR) That said, the DRC-based ratio does have limitations: when clinical suspicion is high, PRA may be the more precise study to calculate the ratio.5Journal of the Endocrine Society. Aldosterone/Direct Renin Concentration Ratio Versus Aldosterone/Plasma Renin Activity for Diagnosis of Primary Hyperaldosteronism: Case Presentation
A common frustration is that the specific cutoff numbers for a “positive” screen vary by lab and by which assay is being used. If your lab recently switched from an older immunoassay to liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measuring aldosterone, the numbers will be systematically lower. One study found that an LC-MS/MS aldosterone of about 11.7 ng/dL was equivalent to roughly 15 ng/dL on a traditional immunoassay, meaning old cutoffs cannot simply be carried forward without adjustment.6PubMed Central. Comparative Analysis of Liquid Chromatography-Tandem Mass Spectrometry and Radioimmunoassay in Determining Plasma Aldosterone Concentration and Plasma Renin Activity for Primary Aldosteronism Screening This matters practically: if you or your doctor are comparing your results against published thresholds, the assay platform behind those numbers needs to match.
How Medications Complicate Screening
This is arguably the trickiest part of the early workup. Many common blood pressure medications alter aldosterone, renin, or both, which directly changes the ARR. A critical review of the literature confirmed that many commonly prescribed antihypertensives have significant effects on these values.7PubMed Central. The effect of medication on the aldosterone-to-renin ratio. A critical review of the literature
The specifics matter. Beta-blockers suppress renin dramatically without changing aldosterone much, which artificially inflates the ratio and can produce false positives. ACE inhibitors and angiotensin receptor blockers lower aldosterone modestly, which could mask a true positive. Calcium channel blockers tend to be the least disruptive. Spironolactone, the very drug often used to treat primary aldosteronism, causes renin to escape suppression and reach very high levels, making the ARR essentially uninterpretable.8PubMed. Influence of antihypertensive medication on aldosterone and renin concentration in the differential diagnosis of essential hypertension and primary aldosteronism
The ideal protocol is to switch patients to medications that minimally affect the ratio (typically a calcium channel blocker and/or an alpha-blocker) for a washout period of two to four weeks before drawing the ARR. For spironolactone and eplerenone, the recommended washout is often six weeks. In practice, this can be difficult for patients with severe or poorly controlled hypertension, and some clinicians opt to interpret the ARR cautiously on existing medications rather than risk a dangerous blood pressure spike during a washout.
Confirmatory Testing
A positive screening ratio does not clinch the diagnosis. The next step is a confirmatory test designed to prove that aldosterone production is truly autonomous, meaning it cannot be suppressed the way it normally would be. Several tests exist, and the evidence behind them is, candidly, not as strong as you might expect for a step this consequential.
A large systematic review and meta-analysis encompassing 55 studies found that the evidence base for every confirmatory test was riddled with problems. Risk of bias was high in over half the studies, and studies using flawed designs overestimated diagnostic accuracy dramatically, by as much as five- to seven-fold.9PubMed Central. Performance of Confirmatory Tests for Diagnosing Primary Aldosteronism: a Systematic Review and Meta-Analysis Under most real-world scenarios, confirmatory testing resulted in more missed cases than false alarms. The overall certainty of evidence across all tests was rated very low.
The most commonly used tests include:
- Saline infusion test: Two liters of saline are infused intravenously over four hours. In a healthy person, the salt load suppresses aldosterone. In primary aldosteronism, aldosterone stays elevated. This can be done with the patient lying down (recumbent) or sitting up (seated), and the two versions perform somewhat differently. When performed with careful mass spectrometry-based aldosterone measurement and minimal patient movement during infusion, this test can achieve excellent accuracy, with one study reporting an area under the curve of 0.985 and sensitivity and specificity both around 96% at the optimal cutoff.10PubMed Central. The saline infusion test with mass spectrometric measurements of aldosterone to confirm primary aldosteronism But the assay used to measure aldosterone matters enormously. Immunoassays can read 58% to 86% higher than mass spectrometry for the same sample, leading to a substantial number of false positive confirmatory results.11PubMed Central. The Saline Infusion Test for Primary Aldosteronism: Implications of Immunoassay Inaccuracy
- Oral salt loading test: The patient eats a high-sodium diet (or takes salt tablets) for several days, then collects urine for 24 hours. This test may be more sensitive than the seated saline infusion test for detecting overt primary aldosteronism, with one head-to-head comparison finding sensitivity of about 85% for the oral test versus 64% for the seated infusion.12Journal of the Endocrine Society. Oral Sodium Loading Test Is More Sensitive Than Seated Saline Infusion Test to Confirm Overt Primary Aldosteronism Positive results on this test have also been linked to higher levels of urine albumin, suggesting a connection to early kidney damage.13PubMed Central. Oral Salt Loading Test Is Associated With 24-Hour Blood Pressure and Organ Damage in Primary Aldosteronism Patients
- Fludrocortisone suppression test: Considered by some to be the most rigorous option, but it requires several days of inpatient observation and is rarely used outside specialized centers.
- Captopril challenge test: An ACE inhibitor is given, and aldosterone is measured before and after. Simpler to perform than saline infusion, but the evidence supporting its accuracy is similarly limited.
No single confirmatory test has emerged as clearly superior. Which one a patient gets often depends on the center’s experience and available laboratory infrastructure. There is also a growing conversation among specialists about whether confirmatory testing should be skipped entirely in patients with very clear-cut screening results, particularly when the ARR is extremely elevated and potassium is low, though this approach has not been universally adopted.
Figuring Out Which Adrenal Gland Is the Problem
Once primary aldosteronism is confirmed, the critical question becomes whether the excess aldosterone is coming from one adrenal gland or both. This distinction drives treatment: a single overactive gland (usually an aldosterone-producing adenoma) can be removed surgically, while bilateral disease (bilateral adrenal hyperplasia) is treated with medications.
The first instinct is to look at a CT scan. And CT does provide useful anatomical information, but its accuracy for subtyping is surprisingly poor. In one large study of over 1,500 patients, CT findings agreed with the definitive test (adrenal vein sampling) only about 68% of the time.14The Journal of Clinical Endocrinology & Metabolism. Significance of Computed Tomography and Serum Potassium in Predicting Subtype Diagnosis of Primary Aldosteronism An earlier study was even more pessimistic, finding CT was inaccurate or unhelpful in 68% of primary aldosteronism patients.15The Journal of Clinical Endocrinology & Metabolism. Comparison of Adrenal Vein Sampling and Computed Tomography in the Differentiation of Primary Aldosteronism A particular danger: about 5% of patients whose CT showed a nodule on one side actually had their aldosterone overproduction coming from the other adrenal gland entirely.14The Journal of Clinical Endocrinology & Metabolism. Significance of Computed Tomography and Serum Potassium in Predicting Subtype Diagnosis of Primary Aldosteronism Operating on the wrong side based on CT alone would be a serious error.
This is why adrenal vein sampling (AVS) is recommended as the standard-of-care for subtyping. AVS is a specialized interventional radiology procedure where catheters are threaded into the veins draining each adrenal gland to measure aldosterone levels directly. If one side’s aldosterone concentration is dramatically higher than the other’s (typically a lateralization index of 2 to 4 or above), that side is the culprit.16PubMed Central. Multifocal, Asymmetric Bilateral Primary Aldosteronism Cannot be Excluded by Strong Adrenal Vein Sampling Lateralization: An International Retrospective Cohort Study Expert consensus statements emphasize AVS as essential for identifying surgically curable disease, though it remains markedly underused.17PubMed. An expert consensus statement on use of adrenal vein sampling for the subtyping of primary aldosteronism
AVS is technically demanding. Success rates vary between centers, and not every hospital has a radiologist experienced enough to cannulate both adrenal veins reliably. The right adrenal vein in particular is notoriously difficult to catheterize due to its anatomy. Failed or ambiguous AVS results are not uncommon and sometimes require a repeat procedure.
Emerging Imaging Alternatives to Adrenal Vein Sampling
Because AVS is invasive, technically challenging, and not available everywhere, researchers have been working on imaging techniques that could identify the source of aldosterone overproduction noninvasively. Two approaches stand out.
The first is 11C-metomidate PET-CT, which uses a radiotracer that binds to enzymes in the adrenal cortex. A prospective clinical trial comparing this scan head-to-head with AVS found that PET sensitivity was around 80% and AVS sensitivity was about 75%, suggesting the imaging approach was at least competitive.18PubMed. 11C-Metomidate PET-CT versus adrenal vein sampling to subtype primary aldosteronism: a prospective clinical trial However, the short half-life of the carbon-11 tracer limits this technique to centers with an on-site cyclotron, which is a major practical barrier.
A more accessible option may be 68Ga-pentixafor PET/CT, which targets a receptor found on aldosterone-producing cells. A pooled analysis of diagnostic accuracy studies found sensitivity of 83% and specificity of 94%, with performance remaining stable across different study designs and protocols.19PubMed. Pooled diagnostic accuracy of (68)Ga-pentixafor PET/CT for aldosterone-producing lesions in primary aldosteronism The gallium-68 tracer can be produced with a generator, making it feasible at a wider range of medical centers. Neither technique has replaced AVS in guidelines yet, but they represent a significant shift toward less invasive subtyping.
When Genetics Enters the Workup
Most primary aldosteronism is caused by somatic mutations, meaning the genetic changes are only in the adrenal gland tissue, not inherited. But a small fraction of cases are familial, caused by germline mutations that run in families. The genes implicated include CYP11B1/B2 (the chimeric gene responsible for the form known as glucocorticoid-remediable aldosteronism, or familial hyperaldosteronism type I), KCNJ5, CLCN2, CACNA1H, and CACNA1D.20PubMed Central. Genetics of Primary Aldosteronism
Genetic testing is most relevant for young patients, those with a strong family history of early hypertension or stroke, and anyone suspected of familial hyperaldosteronism type I. The gold standard for diagnosing that specific form is sequencing the chimeric CYP11B2/CYP11B1 gene. For familial hyperaldosteronism type III, the key test is sequencing for KCNJ5 mutations. Other familial forms exist but lack specific genetic tests and are diagnosed by excluding the first and third types.21PubMed Central. Genetics of Primary Aldosteronism
Familial hyperaldosteronism type I has a unique therapeutic implication: because aldosterone production in this form is driven by the same hormonal signal that drives cortisol, it can be suppressed with low-dose glucocorticoids like dexamethasone. An older approach to diagnosis used a dexamethasone suppression test, which showed good sensitivity and specificity for identifying these patients.22PubMed. Evaluation of the dexamethasone suppression test for the diagnosis of glucocorticoid-remediable aldosteronism However, subsequent work showed that dexamethasone can also suppress aldosterone in some patients with ordinary adenomas or bilateral hyperplasia, which can be misleading.23PubMed. Diagnosis of glucocorticoid-remediable aldosteronism in primary aldosteronism: aldosterone response to dexamethasone and long polymerase chain reaction for chimeric gene The genetic test is now preferred as definitive.
Conditions That Mimic Hyperaldosteronism
Part of the workup involves making sure you are dealing with genuine primary aldosteronism rather than a look-alike condition. The distinction between primary and secondary hyperaldosteronism is fundamental: in secondary disease, high aldosterone is being driven by high renin (from kidney disease, renal artery narrowing, or other causes), while in primary disease, aldosterone is elevated and renin is suppressed.24American Heart Journal. Low-renin (“primary”) hyperaldosteronism: Differential diagnosis and distinction of sub-groups within the syndrome Measuring both hormones simultaneously sorts this out.
A more subtle mimic is pseudohyperaldosteronism, where you see the classic signs of aldosterone excess (high blood pressure and low potassium) but aldosterone itself is actually low. The most commonly cited cause is licorice. Real licorice contains a compound that blocks the enzyme responsible for deactivating cortisol in the kidney, allowing cortisol to flood mineralocorticoid receptors and mimic aldosterone’s effects.25PubMed Central. Pseudohyperaldosteronism, liquorice, and hypertension The diagnostic giveaway is that both renin and aldosterone are suppressed, unlike primary aldosteronism where only renin is low.26Kidney International Reports. Nephrology Rounds Licorice-Induced Pseudohyperaldosteronism Highlights an Underestimated Etiology of Hypertension Other rare genetic conditions (like Liddle syndrome or apparent mineralocorticoid excess) can also produce this picture, though these are uncommon enough that most clinicians encounter them rarely.
Diagnosing Primary Aldosteronism During Pregnancy
Pregnancy presents a particularly challenging scenario. The renin-angiotensin-aldosterone system undergoes dramatic physiological changes during normal pregnancy: both renin and aldosterone rise substantially, which makes the usual screening ratio much harder to interpret. On top of that, the standard confirmatory tests (saline infusion, salt loading) are generally contraindicated in pregnancy, and subtype differentiation with AVS is also off the table.27PubMed Central. Primary aldosteronism in pregnancy
Diagnosis during pregnancy therefore relies on a simpler pattern: suppressed renin that stays low despite the physiological increases pregnancy normally brings, combined with aldosterone levels disproportionately high even by pregnancy standards. Researchers have developed nomograms to help identify cases by adjusting for the expected hormone changes across trimesters.28PubMed. Management and Outcomes of Primary Aldosteronism in Pregnancy: A Systematic Review In most cases, definitive workup is deferred until after delivery, and the focus during pregnancy shifts to safe blood pressure control.
Why Completing the Full Workup Changes Outcomes
The effort invested in moving through screening, confirmation, and subtyping pays off in treatment outcomes. A meta-analysis comparing surgery with targeted medical therapy (primarily mineralocorticoid receptor antagonists like spironolactone) found that surgery was associated with roughly a 66% lower risk of death and a 45% lower risk of major adverse cardiovascular events. Surgery also significantly reduced the risk of heart failure hospitalization and progression to chronic kidney disease.29PubMed Central. Time to Benefit of Surgery vs Targeted Medical Therapy for Patients With Primary Aldosteronism: A Meta-analysis These benefits emerge relatively quickly: in absolute terms, treating 200 patients with surgery instead of medical therapy prevented one death within about a year.
On the structural heart level, a separate meta-analysis confirmed that adrenalectomy produces significantly greater reduction in heart muscle thickness compared to drug therapy, with shorter hypertension duration predicting greater improvement. Patients who had surgery also saw modest improvement in heart pump function, while high dietary sodium blunted the effectiveness of medications.30PubMed. Adrenalectomy Versus Medical Therapy in Primary Aldosteronism: A Meta-Analysis of Long-Term Cardiac Remodeling and Function: Medical versus Adrenalectomy Treatment Compared in Hyperaldosteronism (MATCH) Study None of these surgical benefits are available to patients who are never properly subtyped, because without knowing which gland is overproducing, surgery cannot be offered.
Defining Success After Treatment
Once a patient undergoes adrenalectomy or starts medical therapy, the workup is not entirely over. Clinicians need standardized ways to evaluate whether the treatment actually worked. The Primary Aldosteronism Surgical Outcome (PASO) study established consensus criteria covering six possible outcomes, ranging from complete biochemical and clinical success to absent success. These criteria examine blood pressure, antihypertensive drug use, potassium levels, aldosterone, and renin after treatment.31The Lancet Diabetes & Endocrinology. The Primary Aldosteronism Surgical Outcome (PASO) study: methods, criteria and outcomes
Complete biochemical success means aldosterone and renin have normalized without mineralocorticoid receptor antagonists. Complete clinical success means blood pressure has normalized without any antihypertensive drugs. Many patients achieve biochemical cure after surgery but still need some blood pressure medication afterward, reflecting the fact that long-standing hypertension from any cause can leave lasting vascular changes. Partial success is still valuable: fewer pills, lower blood pressure, and normalized potassium all translate to reduced cardiovascular risk over time, even if the patient is not completely medication-free.