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PubMed This is a summary of 17 peer-reviewed journal articles Updated
Endocrinology · Primary Aldosteronism

The Diagnostic Journey: Screening and Confirmatory Testing

At a Glance

Diagnosing Primary Aldosteronism starts with an Aldosterone-to-Renin Ratio (ARR) blood test to check for high aldosterone and suppressed renin. Patients often need a medication washout before testing. If the ARR is high, a confirmatory saline infusion test may follow.

The journey to diagnosing Primary Aldosteronism (PA) is a precise process. Because your hormones are sensitive to everything from the medications you take to how you are sitting when your blood is drawn, preparation is the most important part of the journey [1][2].

Step 1: The Screening Test (ARR)

The first step is a blood test called the Aldosterone-to-Renin Ratio (ARR) [3]. This test measures two things at once to see if they are out of balance:

  • Aldosterone: The hormone that is being overproduced.
  • Renin: The enzyme that should be low if you have PA.

The key to a PA diagnosis is renin suppression. In a healthy person, if aldosterone is high, renin should also be high to trigger it. In PA, your adrenal glands pump out aldosterone “autonomously,” which signals your body to shut down renin production [4][5]. Therefore, a high ARR usually means you have high aldosterone and very low renin.

Preparing for the Blood Draw

To ensure your ARR result is accurate, your doctor will ask you to follow specific “standardized conditions” [6]:

  • Timing: Testing is typically done in the morning, usually within a few hours of waking up [2].
  • Posture: You will likely be asked to sit quietly for 5 to 15 minutes before the blood is drawn, as standing or lying down can change your hormone levels [7].
  • Medication Washout: This is often the most challenging part. Many common blood pressure drugs—especially “water pills” (diuretics) and medications like spironolactone—can cause false results [2][8]. Your doctor may ask you to stop these for 2 to 4 weeks, switching you to “safe” alternative medications that don’t interfere with the test [9][10].

Step 2: Confirmatory Testing

If your ARR screening is positive, the next step is usually a confirmatory test [11]. The goal of these tests is to see if your body can “turn off” aldosterone production when it is given a high dose of salt. In a healthy person, salt suppresses aldosterone; in someone with PA, the aldosterone stays high regardless [12].

Common confirmatory tests include:

  • Saline Infusion Test (SIT): You receive a high volume of salt water through an IV over 4 hours, and your aldosterone is measured afterward [12][13].
  • Oral Salt Loading Test: You eat a high-salt diet for several days, then provide a 24-hour urine sample to measure aldosterone levels [14].

When Can You Skip the Second Step?

Not every patient needs a confirmatory test. According to recent clinical guidelines, if your screening results are very clear—meaning you have very high aldosterone, a high ARR, and low potassium—your doctor may “bypass” the confirmatory test and move straight to identifying the subtype [15][16]. This is because the probability of PA is so high in these cases that further proof isn’t needed before starting the next phase of care [17].

Common questions in this guide

What is the ARR test for Primary Aldosteronism?
The Aldosterone-to-Renin Ratio (ARR) is a blood test that measures both aldosterone and renin levels. In Primary Aldosteronism, aldosterone is inappropriately high while renin is very low, indicating the adrenal glands are overproducing aldosterone autonomously.
Do I need to stop my blood pressure medication before an ARR test?
Yes, many common blood pressure medications, especially diuretics and spironolactone, can interfere with the test results. Your doctor will likely have you complete a medication washout for 2 to 4 weeks and switch you to safe alternative medications that do not affect the ARR.
How do I prepare for my aldosterone and renin blood draw?
Hormone blood tests are highly sensitive to timing and posture. Testing is usually done in the morning within a few hours of waking up. You will also need to sit quietly for 5 to 15 minutes before the blood is drawn, as standing or lying down can change your hormone levels.
What happens during a confirmatory test for Primary Aldosteronism?
A confirmatory test, such as a saline infusion or oral salt loading test, checks if your body can turn off aldosterone production when exposed to a high dose of salt. In a healthy person, salt suppresses aldosterone, but in someone with Primary Aldosteronism, the aldosterone stays high.
Are confirmatory tests always required for a diagnosis?
Not always. If your initial screening results show very high aldosterone combined with low potassium and a high ARR, your doctor may bypass the confirmatory test. In these cases, the probability of the condition is high enough to move directly to identifying the specific subtype.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.How long do I need to be off my current blood pressure medications (like diuretics or beta-blockers) before the ARR test is accurate?
  2. 2.Are there 'safe' blood pressure medications I can switch to during my medication washout period?
  3. 3.What specific preparation (like fasting or sitting for a certain time) should I follow on the morning of my blood draw?
  4. 4.Given my high aldosterone and low renin levels, do I definitely need a confirmatory test, or can we move straight to subtyping?
  5. 5.If we do a confirmatory test, which one (saline infusion or salt loading) do you recommend for me, and what are the risks?

Questions For You

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References

References (17)
  1. 1

    SFE/SFHTA/AFCE primary aldosteronism consensus: Introduction and handbook.

    Amar L, Baguet JP, Bardet S, et al.

    Annales d'endocrinologie 2016; (77(3)):179-86.

    PMID: 27315757
  2. 2

    The effect of medication on the aldosterone-to-renin ratio. A critical review of the literature.

    Alnazer RM, Veldhuizen GP, Kroon AA, de Leeuw PW

    Journal of clinical hypertension (Greenwich, Conn.) 2021; (23(2)):208-214 doi:10.1111/jch.14173.

    PMID: 33460525
  3. 3

    A renin-ssance in primary aldosteronism testing: obstacles and opportunities for screening, diagnosis, and management.

    Raizman JE, Diamandis EP, Holmes D, et al.

    Clinical chemistry 2015; (61(8)):1022-7 doi:10.1373/clinchem.2015.242990.

    PMID: 26106077
  4. 4

    Comparing ARR Versus Suppressed PRA as Screening Tests for Primary Aldosteronism.

    Marcelli M, Bi C, Funder JW, McPhaul MJ

    Hypertension (Dallas, Tex. : 1979) 2024; (81(10)):2072-2081 doi:10.1161/HYPERTENSIONAHA.124.22884.

    PMID: 39041222
  5. 5

    Pathology of Aldosterone Biosynthesis and its Action.

    Gao X, Yamazaki Y, Tezuka Y, et al.

    The Tohoku journal of experimental medicine 2021; (254(1)):1-15 doi:10.1620/tjem.254.1.

    PMID: 34011803
  6. 6

    Case detection in primary aldosteronism: high-diagnostic value of the aldosterone-to-renin ratio when performed under standardized conditions.

    Vorselaars WMCM, Valk GD, Vriens MR, et al.

    Journal of hypertension 2018; (36(7)):1585-1591 doi:10.1097/HJH.0000000000001718.

    PMID: 29528872
  7. 7

    Effect of postural changes on aldosterone to plasma renin ratio in patients with suspected secondary hypertension.

    Barigou M, Ah-Kang F, Orloff E, et al.

    Annales de cardiologie et d'angeiologie 2015; (64(3)):169-74.

    PMID: 26051856
  8. 8

    Mineralocorticoid Receptor Antagonists Decrease the Rates of Positive Screening for Primary Aldosteronism.

    Tezuka Y, Turcu AF

    Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists 2020; (26(12)):1416-1424 doi:10.4158/EP-2020-0277.

    PMID: 33471733
  9. 9

    Effect of Moxonidine on the Aldosterone/Renin Ratio in Healthy Male Volunteers.

    Ahmed AH, Gordon RD, Ward G, et al.

    The Journal of clinical endocrinology and metabolism 2017; (102(6)):2039-2043 doi:10.1210/jc.2016-3821.

    PMID: 28324033
  10. 10

    The Effects of Verapamil, Hydralazine, and Doxazosin on Renin, Aldosterone, and the Ratio Thereof.

    Veldhuizen GP, Alnazer RM, de Leeuw PW, Kroon AA

    Cardiovascular drugs and therapy 2023; (37(2)):283-289 doi:10.1007/s10557-021-07262-3.

    PMID: 34515895
  11. 11

    Quantitative Value of Aldosterone-Renin Ratio for Detection of Aldosterone-Producing Adenoma: The Aldosterone-Renin Ratio for Primary Aldosteronism (AQUARR) Study.

    Maiolino G, Rossitto G, Bisogni V, et al.

    Journal of the American Heart Association 2017; (6(5)) doi:10.1161/JAHA.117.005574.

    PMID: 28529209
  12. 12

    A combination of captopril challenge test after saline infusion test improves diagnostic accuracy for primary aldosteronism.

    Lin C, Yang J, Fuller PJ, et al.

    Clinical endocrinology 2020; (92(2)):131-137 doi:10.1111/cen.14134.

    PMID: 31774187
  13. 13

    Using plasma aldosterone concentrations at 1 h of saline infusion test for the diagnosis of primary aldosteronism.

    Phonanuwong R, Jannoo S, Chanthanuwat S, Soonthornpun S

    Journal of hypertension 2023; (41(9)):1493-1497 doi:10.1097/HJH.0000000000003504.

    PMID: 37432888
  14. 14

    Re-Assessment of the Oral Salt Loading Test Using a New Chemiluminescent Enzyme Immunoassay Based on a Two-Step Sandwich Method to Measure 24-Hour Urine Aldosterone Excretion.

    Ozeki Y, Kinoshita M, Miyamoto S, et al.

    Frontiers in endocrinology 2022; (13()):859347 doi:10.3389/fendo.2022.859347.

    PMID: 35388294
  15. 15

    Sparing confirmatory testing in primary aldosteronism (SCIPA): a multicenter retrospective diagnostic accuracy study.

    Ong Lopez AMC, Tiu LE, Dimayuga DC, et al.

    BMC endocrine disorders 2024; (24(1)):105 doi:10.1186/s12902-024-01638-w.

    PMID: 38978003
  16. 16

    Performance of Confirmatory Tests for Diagnosing Primary Aldosteronism: a Systematic Review and Meta-Analysis.

    Leung AA, Symonds CJ, Hundemer GL, et al.

    Hypertension (Dallas, Tex. : 1979) 2022; (79(8)):1835-1844 doi:10.1161/HYPERTENSIONAHA.122.19377.

    PMID: 35652330
  17. 17

    Development of a Prediction Score to Avoid Confirmatory Testing in Patients With Suspected Primary Aldosteronism.

    Burrello J, Amongero M, Buffolo F, et al.

    The Journal of clinical endocrinology and metabolism 2021; (106(4)):e1708-e1716 doi:10.1210/clinem/dgaa974.

    PMID: 33377974

This page explains diagnostic testing for Primary Aldosteronism for educational purposes only. Always consult your endocrinologist or primary care doctor regarding medication washouts and interpreting your specific ARR test results.

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