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PubMed This is a summary of 23 peer-reviewed journal articles Updated
Endocrinology

Navigating Your Diagnosis: From Screening to Adrenal Mapping

At a Glance

Familial hyperaldosteronism type II is diagnosed in stages: an aldosterone-renin ratio screens for excess aldosterone, confirmatory testing may follow, and CT or adrenal venous sampling helps determine whether one or both adrenal glands are involved and whether surgery is appropriate.

Diagnosing Primary Aldosteronism (PA) is a multi-step process designed to prove that your body is producing too much aldosterone and to find out exactly where it is coming from [1]. Because Familial Hyperaldosteronism Type II (FH-II) is clinically similar to the sporadic version of the disease, the testing path starts with biochemical screening, moves to confirmation if needed, and proceeds to imaging and localization if surgery is a consideration [2][3].

Phase 1: Screening with the ARR

The first step is the Aldosterone-Renin Ratio (ARR) [1]. This screening test compares the amount of aldosterone in your blood to the amount of renin. In PA, your aldosterone is typically elevated or inappropriately normal, while your renin is suppressed [4]. The ARR is a screening tool, not a definitive diagnosis on its own; it must be interpreted alongside the absolute aldosterone levels and your clinical context.

The ARR Preparation Checklist

To get the most accurate ARR result, your internal chemistry must be accounted for.

  • Correct Potassium: Low potassium levels can artificially lower your aldosterone. If possible, your clinician will aim to correct your potassium before the draw [5][6].
  • Morning Timing: Samples are usually collected in the morning [5].
  • The “Sit Still” Rule: You should be seated for 5 to 15 minutes before the draw [5][7].
  • Salt Intake: Do not artificially restrict your salt intake before the test, as low salt can confuse the results [5][8].
  • Medication Review: Certain medications interfere with the ARR. Never stop a medication without a doctor’s supervision, as stopping antihypertensives can be dangerous. Your prescribing team will decide if it is safe to pause certain drugs (like MRAs or diuretics) or switch to “neutral” alternatives (like verapamil or alpha-blockers) prior to testing [3][9]. Sometimes, a washout is unsafe, and the test must be interpreted while you remain on your current medications.

Phase 2: Confirming the Diagnosis

If your ARR suggests PA, your doctor may order a confirmatory test to prove that your aldosterone stays high even when it should naturally suppress [10][11].

  • Saline Infusion Test: You receive 2 liters of salt water through an IV. This extra salt normally makes aldosterone drop; in PA, it stays elevated [12]. Note: This test may be unsafe if you have severe uncontrolled hypertension, heart failure, or advanced kidney disease.
  • Captopril Challenge: You take a dose of a specific medication (Captopril), and your blood is tested afterward [13].
  • Bypassing Confirmation: Under the 2025 Endocrine Society guidelines, if your screening indicates a very high probability of PA (for example, spontaneous hypokalemia, undetectable renin, and aldosterone >20 ng/dL depending on the assay), your doctor may bypass confirmation and move straight to imaging [14][15].

Phase 3: Localization (Finding the Source)

Once PA is confirmed, the goal is to determine if the problem is in one gland (unilateral) or both (bilateral). In CLCN2-associated FH-II, it is most often bilateral, but if surgical cure is being considered, exact localization is required [16][17].

  • CT Scan: A CT scan looks for growths (nodules) on the adrenal glands. However, CT scans can be misleading—they might show a non-functioning “lump” or miss small areas of hyperactivity [18][19].
  • Adrenal Venous Sampling (AVS): AVS is the preferred test if you are a potential candidate for surgery [17]. A specialist inserts a small tube into the veins draining each adrenal gland to measure aldosterone levels directly [20].
    • If AVS shows unilateral disease, surgery (adrenalectomy) is an option that improves or cures PA in many patients [21].
    • If AVS shows bilateral disease (common in FH-II), or if you are not a surgical candidate, the condition is managed with life-long medication [22][23].

Because AVS has technical limitations and carries risks, it is a shared decision made with a specialist endocrine team, factoring in your genetic diagnosis and overall health.

Common questions in this guide

What does the aldosterone-renin ratio show in FH-II?
The aldosterone-renin ratio compares the amount of aldosterone in your blood with renin, a hormone that helps regulate blood pressure. In primary aldosteronism, aldosterone is often high or inappropriately normal while renin is low. A high ratio is a screening result, not a diagnosis by itself, so clinicians also consider the absolute hormone levels, potassium, medicines, and clinical context.
How should I prepare for an ARR blood test?
Your clinician may correct low potassium before testing, usually collect the sample in the morning, and ask you to sit for 5 to 15 minutes first. Do not deliberately restrict salt before the test. Tell your care team about every medicine you take, and never stop a blood-pressure medicine without medical supervision.
What confirmatory tests may follow an abnormal ARR?
A saline infusion test gives salt water through an IV and checks whether aldosterone falls, while a captopril challenge measures aldosterone after you take captopril. Saline infusion may be unsafe with severe uncontrolled hypertension, heart failure, or advanced kidney disease. When the results make primary aldosteronism very likely, a clinician may decide to move forward without confirmatory testing.
Can a CT scan show which adrenal gland is causing FH-II?
A CT scan can identify an adrenal nodule, but the nodule may not be producing hormones, and CT can miss small overactive areas. If surgery is being considered, adrenal venous sampling is usually preferred because it directly compares aldosterone production from each adrenal gland.
What is adrenal venous sampling, and why might I need it?
During adrenal venous sampling, a specialist places a small catheter in the veins draining each adrenal gland and measures aldosterone from each side. The results help distinguish disease in one gland from disease in both glands, which can guide the choice between adrenalectomy and lifelong medication. Because the procedure has technical limitations and risks, an endocrine team should weigh its potential benefits for you.
Does FH-II usually affect one adrenal gland or both?
CLCN2-associated FH-II most often affects both adrenal glands. If testing confirms that one gland is responsible, adrenalectomy may be considered; disease affecting both glands or people who are not surgical candidates is generally managed with lifelong medication.

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my potassium fully corrected before my ARR blood draw, and how might my current level have influenced the result?
  2. 2.Which of my current blood pressure medications could cause a false-positive or false-negative result, and is it safe to adjust them, or should we interpret the ARR as is?
  3. 3.Based on my renin and absolute aldosterone levels, do I meet the criteria to bypass confirmatory testing?
  4. 4.If my CT scan shows a nodule on only one side, do we still need AVS to confirm if the other gland is also overproducing aldosterone?
  5. 5.Given my suspected FH-II diagnosis, what are the expected outcomes and risks if we pursue AVS and possible surgery versus medical management?

References

References (23)
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    Differences in the clinical and hormonal presentation of patients with familial and sporadic primary aldosteronism.

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This page is for informational purposes only and does not constitute medical advice about familial hyperaldosteronism type II. Your endocrinology team should interpret your ARR and imaging and decide whether medication changes, AVS, or surgery are safe for you.