Aldosterone Plasma Renin Activity Ratio (ARR) LC–MS/MS Biomarker Testing
It measures aldosterone, renin activity, and their ratio to screen for primary aldosteronism; order through Vitals Vault with Quest lab access.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
This test looks at two hormones that help control your blood pressure and salt balance: aldosterone and renin. It also calculates a ratio between them (often called the aldosterone–renin ratio, or ARR).
The ARR is most useful when you have high blood pressure that is hard to control, low potassium, or a pattern that makes your clinician wonder about “primary aldosteronism” (also called Conn syndrome). That condition can be missed for years because the symptoms can look like typical hypertension.
Because aldosterone and renin change with posture, salt intake, and many common blood pressure medications, the most important part of this test is getting the right prep and interpreting the result in context rather than treating the ratio as a standalone diagnosis.
Do I need a Aldosterone Plasma Renin Activity Ratio LC MS MS test?
You may want an aldosterone plasma renin activity ratio (ARR) test if you have high blood pressure that started at a younger age, needs multiple medications, or stays high despite good adherence. The test is also commonly considered when you have unexplained low potassium, muscle weakness or cramps, frequent urination, or headaches alongside hypertension.
This test can be especially helpful if your clinician suspects a hormone-driven cause of high blood pressure. Primary aldosteronism is one of the more treatable causes, and identifying it can change what “best treatment” looks like, including whether you need different medications, confirmatory testing, or imaging.
You might also be a candidate if you have an adrenal nodule found incidentally on imaging, or if you have a family history of early strokes or severe hypertension. In those situations, an ARR can help decide whether further endocrine evaluation is warranted.
Your result should support clinician-directed care rather than self-diagnosis, because medication effects and collection conditions can shift aldosterone, renin, and the ratio in ways that mimic disease.
This is a laboratory-developed test performed in a CLIA-certified lab; results are used for screening and risk assessment and are not, by themselves, a diagnosis.
Lab testing
Order the aldosterone–renin ratio test through Vitals Vault and complete your draw at Quest.
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
With Vitals Vault, you can order an aldosterone–plasma renin activity ratio test without waiting for a separate lab referral, then complete your draw at a participating Quest location.
Once results are in, you can use PocketMD to review what “low,” “in range,” or “high” patterns may suggest, and to generate a focused list of follow-up questions for your clinician—especially around medication effects, potassium status, and whether confirmatory testing is appropriate.
If your numbers are borderline or your prep was not ideal (for example, you were on a medication that suppresses renin), Vitals Vault makes it easy to reorder the same test after you and your clinician decide on a safer, more interpretable retest plan.
- Convenient blood draw at Quest locations
- PocketMD guidance for next-step questions and retest planning
- Clear, shareable results you can bring to your clinician
Key benefits of Aldosterone Plasma Renin Activity Ratio LC MS MS testing
- Helps screen for primary aldosteronism, a common and treatable cause of secondary hypertension.
- Clarifies whether your blood pressure pattern looks more “aldosterone-driven” (high aldosterone with low renin) versus other causes.
- Supports smarter medication decisions by showing how strongly renin is suppressed or stimulated.
- Adds context when potassium is low or fluctuating, even if you feel fine.
- Guides whether confirmatory testing (suppression tests) may be worth pursuing with your clinician.
- Improves interpretation when paired with electrolytes and kidney markers that affect the renin–angiotensin–aldosterone system.
- Makes it easier to track trends over time when you repeat the test under consistent prep conditions.
What is Aldosterone Plasma Renin Activity Ratio LC MS MS?
This test measures plasma aldosterone and plasma renin activity (PRA), then reports a calculated aldosterone-to-renin ratio (ARR). Aldosterone is a hormone made by your adrenal glands that tells your kidneys to retain sodium and water and to excrete potassium. Renin is an enzyme released by the kidneys that helps regulate aldosterone through the renin–angiotensin–aldosterone system (RAAS).
In many people with primary aldosteronism, aldosterone is inappropriately high for the body’s needs, while renin is suppressed because the body senses higher blood volume and blood pressure. That “high aldosterone + low renin” pattern is why the ratio can be a useful screening tool.
The “LC–MS/MS” part refers to liquid chromatography–tandem mass spectrometry, a measurement method often used for hormones because it can improve analytical specificity compared with some immunoassays. Even with strong analytical methods, clinical interpretation still depends heavily on collection conditions and medications.
Why the ratio matters (not just the aldosterone number)
Aldosterone can be mildly elevated for many reasons, including low sodium intake, diuretics, or standing upright before the draw. The ARR uses renin as the counterbalance. When aldosterone is high but renin is also high, the body may simply be responding appropriately to a stimulus. When aldosterone is high while renin is low, that mismatch is more suspicious for autonomous aldosterone production.
Plasma renin activity vs renin concentration
Some labs report renin as plasma renin activity (PRA), while others report direct renin concentration (DRC). The ratio cutoffs and units differ between PRA-based and DRC-based testing, so you should not compare ratios across methods without guidance. This page is specific to a PRA-based ARR.
What do my Aldosterone Plasma Renin Activity Ratio LC MS MS results mean?
Low ARR (or low aldosterone relative to renin)
A low ratio usually means aldosterone is not elevated compared with renin. This pattern can be seen when your RAAS is appropriately activated (for example, dehydration, low salt intake, or certain diuretics) and renin rises more than aldosterone. It can also occur if aldosterone is suppressed from medications or from conditions that reduce adrenal aldosterone production. A low ARR generally makes primary aldosteronism less likely, but it does not rule out other causes of hypertension.
ARR in the expected range
An in-range ratio suggests aldosterone and renin are in a more typical relationship for the collection conditions. If your blood pressure is still high, your clinician may look for other contributors such as sleep apnea, kidney disease, thyroid issues, medication effects, or lifestyle factors. If suspicion for primary aldosteronism remains high (for example, resistant hypertension with low potassium), your clinician may still consider repeat testing with stricter prep or additional evaluation.
High ARR (especially with high aldosterone and low renin)
A high ratio means aldosterone is elevated relative to renin, which can be a screening signal for primary aldosteronism. Many clinicians look not only at the ratio but also at whether aldosterone is clearly elevated and whether renin is suppressed, because a high ratio can sometimes be driven by very low renin alone. If your result is high, typical next steps include confirming potassium status, reviewing medications and salt intake, and discussing confirmatory suppression testing or referral to an endocrinologist or hypertension specialist.
Factors that influence aldosterone, renin, and the ARR
Many blood pressure medications can change renin and aldosterone for weeks, including diuretics, ACE inhibitors, ARBs, beta blockers, mineralocorticoid receptor antagonists (such as spironolactone or eplerenone), and some calcium channel blockers. Salt intake, hydration, time of day, recent exercise, stress, and whether you were seated or upright before the draw can also shift results. Kidney function and potassium levels strongly affect the RAAS and can change interpretation. For the most interpretable result, follow the collection instructions provided with your order and review your medication list with your clinician before you test.
What’s included
- Aldo/Pra Ratio
- Aldosterone, Lc/Ms/Ms
- Plasma Renin Activity, Lc/Ms/Ms
Frequently Asked Questions
What is the aldosterone–renin ratio (ARR) used for?
The ARR is mainly used to screen for primary aldosteronism, a condition where your adrenal glands make too much aldosterone. It is most often considered in resistant hypertension, hypertension with low potassium, early-onset hypertension, or when an adrenal nodule is found.
Do I need to fast for an aldosterone and renin activity test?
Fasting requirements vary by lab protocol, but many ARR collections do not require strict fasting. What usually matters more is posture (seated vs upright), time of day, salt intake, and medication effects. Follow the instructions that come with your order and confirm with your clinician if you are unsure.
Which medications can affect aldosterone, renin, or the ARR?
Common medications that can significantly affect results include diuretics, ACE inhibitors, ARBs, beta blockers, mineralocorticoid receptor antagonists (spironolactone/eplerenone), and some calcium channel blockers. Do not stop any medication on your own; ask your clinician whether a medication adjustment is safe and appropriate before testing or retesting.
What does a high ARR mean if my aldosterone is normal?
A high ratio can sometimes happen because renin is very low, even if aldosterone is not clearly elevated. Many clinicians interpret the ARR alongside the absolute aldosterone value, the renin value, potassium level, and collection conditions. If the pattern is borderline, a repeat test with optimized prep or confirmatory testing may be discussed.
How is primary aldosteronism confirmed after an abnormal ARR?
Confirmation typically involves additional testing directed by a clinician, such as suppression testing (for example, saline infusion or oral salt loading protocols), and then determining whether excess aldosterone is coming from one adrenal gland or both. Imaging and specialized procedures may be used depending on the case.
When should I retest the ARR?
Retesting is often considered when the first draw was done under non-ideal conditions (recent medication changes, unclear posture timing, abnormal potassium, or inconsistent salt intake) or when results are borderline but clinical suspicion remains. Your clinician can advise on timing because some medication effects can persist for weeks.