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PubMed This is a summary of 83 peer-reviewed journal articles Updated
Endocrinology

Familial Hyperaldosteronism Type II: A Patient Guide

At a Glance

Familial hyperaldosteronism type II is an inherited cause of excess aldosterone, often linked to a CLCN2 gene variant. Long-term treatment with medicines that block aldosterone’s effects, blood pressure and potassium checks, and targeted testing for close relatives help reduce heart and kidney risks.

Familial Hyperaldosteronism Type II (FH-II) is a rare, inherited condition that causes your adrenal glands to produce an excessive amount of the hormone aldosterone [1]. In many cases, this hormonal overproduction is driven by a pathogenic variant (a mutation) in the CLCN2 gene, which acts as a faulty switch in the adrenal cells, causing them to hold onto salt and flush out potassium [2][3]. Because this process looks and feels exactly like the more common, non-inherited version of Primary Aldosteronism (PA), FH-II often remains a “hidden” diagnosis for years, frequently masked as standard high blood pressure until a doctor looks closer at your age or family history [4][5]. It is important to note that the FH-II label has historically included various genetic causes, but this guide focuses on CLCN2-associated familial primary aldosteronism, which is currently the most well-defined subtype.

Living with FH-II requires a shift in perspective from managing a single number on a blood pressure cuff to protecting your entire cardiovascular system. The core of this management rests on three pillars: recognizing when symptoms require urgent attention versus routine care, pursuing a precise diagnosis for yourself and appropriate relatives, and maintaining long-term medical therapy. While the daily reality of the condition often involves routine high blood pressure or fatigue, it can occasionally lead to urgent issues like severe muscle weakness or a hypertensive crisis [6][7]. Understanding the difference between these situations is the first step in regaining a sense of control over your health [8].

Because FH-II is a genetic condition, your diagnosis serves as a roadmap for your family. Through a process called cascade testing, your parents, siblings, and children can be offered targeted screening and genetic counseling for the same genetic markers. This can potentially prevent the heart and kidney damage that occurs when high blood pressure goes untreated for decades [9][10]. This clarity allows your care team to move past the generic treatments used for essential hypertension and focus on the specific biological mechanisms driving your disease [1].

For most people with CLCN2-associated disease, health is maintained through lifelong medical management using Mineralocorticoid Receptor Antagonists (MRAs), such as spironolactone or eplerenone [11]. The goal of this therapy is threefold: to safely lower your blood pressure, to bring your potassium levels into an individualized normal range, and to gradually “unsuppress” your renin levels [12][13]. An unsuppressed renin level is used by many specialists as a helpful adjunctive marker to show that your medication is shielding your body from the effects of excess aldosterone, though it must always be interpreted alongside your blood pressure and kidney function [13][14]. With an individualized monitoring plan and a dedicated care team, you can manage the risks of FH-II and live a full, active life.

Note: This guide is meant to supplement, not replace, an endocrinologist’s or genetic counselor’s care plan. Never change your blood pressure, MRA, or potassium medications on your own.

In this guide

6 chapters

01

Understanding Familial Hyperaldosteronism Type II and Red Flags

Learn about familial hyperaldosteronism type II, CLCN2 testing, family clues, blood pressure and potassium warning signs, and when to seek emergency care.

02

Symptoms and Look-Alikes: Identifying Your Type of PA

Learn how familial hyperaldosteronism type II is distinguished from sporadic primary aldosteronism through symptoms, family history, and genetic testing.

03

The Biology of FH-II: How the CLCN2 Gene Drives Aldosterone

Learn how CLCN2 variants cause familial hyperaldosteronism type II, how FH-II is inherited, and what genetic results mean for treatment and family testing.

04

Navigating Your Diagnosis: From Screening to Adrenal Mapping

Learn how familial hyperaldosteronism type II is diagnosed, from ARR screening and confirmatory tests to CT imaging, adrenal venous sampling, and surgery.

05

Managing FH-II: Medication Goals and Safety

Learn how familial hyperaldosteronism type II treatment uses MRAs to control blood pressure, manage potassium, restore renin, and monitor kidney function.

06

Protecting Your Long-Term Health and Your Family

Learn how Familial Hyperaldosteronism Type II affects long-term heart and kidney health, how MRAs are monitored, and why CLCN2 family testing matters.

Common questions in this guide

What is familial hyperaldosteronism type II?
Familial hyperaldosteronism type II is a rare inherited condition in which the adrenal glands produce too much aldosterone. The excess hormone can raise blood pressure and cause the body to lose potassium. The best-defined form discussed here is associated with a pathogenic variant in the CLCN2 gene.
How might doctors distinguish FH-II from ordinary primary aldosteronism?
Both conditions can cause excess aldosterone, high blood pressure, and similar potassium or renin findings. A young age at diagnosis, several relatives with early high blood pressure, or a known familial variant may prompt genetic counseling and targeted testing. The diagnosis should be based on the complete medical, family, laboratory, and genetic picture.
What medicines are commonly used to treat CLCN2-associated FH-II?
Treatment usually involves long-term use of a mineralocorticoid receptor antagonist, such as spironolactone or eplerenone. These medicines help counter aldosterone’s effects, lower blood pressure, and support a safe potassium level. The dose must be individualized and monitored by the care team.
Why does renin monitoring matter in FH-II?
Renin is a hormone measured as part of follow-up for aldosterone excess. Some specialists use a rise from a suppressed renin level as an additional sign that treatment is blocking aldosterone’s effects, but renin must be interpreted with blood pressure and kidney function. The appropriate target is individualized.
Should my relatives be tested for FH-II?
Close relatives such as parents, siblings, and children may be offered genetic counseling and targeted testing when a familial variant is identified. This cascade testing can find affected relatives earlier and may help prevent heart and kidney damage from untreated high blood pressure. A genetics professional can explain which relatives should be tested and how results may affect care.
Which FH-II symptoms should receive urgent medical attention?
Severe muscle weakness or a hypertensive crisis can signal a potentially urgent problem and should not be managed by changing medicines on your own. Routine high blood pressure or fatigue still deserves timely follow-up because untreated high blood pressure can harm the heart and kidneys. Contact your clinician or seek urgent care based on symptom severity and their instructions.

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Since FH-II can be a 'hidden' diagnosis, what specific findings in my history made you suspect a genetic cause over sporadic primary aldosteronism?
  2. 2.How will my treatment plan differ if we determine my condition is bilateral, as is common with CLCN2-associated disease?
  3. 3.What is our individualized long-term target for my renin levels, and how will we monitor them to ensure my medication dose is correct without risking side effects?
  4. 4.Can you help me coordinate genetic counseling and targeted testing for my siblings and children?

References

References (14)
  1. 1

    CLCN2 chloride channel mutations in familial hyperaldosteronism type II.

    Scholl UI, Stölting G, Schewe J, et al.

    Nature genetics 2018; (50(3)):349-354 doi:10.1038/s41588-018-0048-5.

    PMID: 29403011
  2. 2

    A gain-of-function mutation in the CLCN2 chloride channel gene causes primary aldosteronism.

    Fernandes-Rosa FL, Daniil G, Orozco IJ, et al.

    Nature genetics 2018; (50(3)):355-361 doi:10.1038/s41588-018-0053-8.

    PMID: 29403012
  3. 3

    Elevated aldosterone and blood pressure in a mouse model of familial hyperaldosteronism with ClC-2 mutation.

    Schewe J, Seidel E, Forslund S, et al.

    Nature communications 2019; (10(1)):5155 doi:10.1038/s41467-019-13033-4.

    PMID: 31727896
  4. 4

    Differences in the clinical and hormonal presentation of patients with familial and sporadic primary aldosteronism.

    Araujo-Castro M, Parra P, Martín Rojas-Marcos P, et al.

    Frontiers in endocrinology 2024; (15()):1336306 doi:10.3389/fendo.2024.1336306.

    PMID: 38495792
  5. 5

    Pathogenesis of Familial Hyperaldosteronism Type II: New Concepts Involving Anion Channels.

    Stowasser M, Wolley M, Wu A, et al.

    Current hypertension reports 2019; (21(4)):31 doi:10.1007/s11906-019-0934-y.

    PMID: 30949771
  6. 6

    Normotensive hypokalemic primary hyperaldosteronism mimicking clinical features of anorexia nervosa in a young patient: A case report.

    Huang YC, Tsai MH, Fang YW, Tu ML

    Medicine 2020; (99(29)):e20826 doi:10.1097/MD.0000000000020826.

    PMID: 32702825
  7. 7

    Lethal Arrhythmia Induced by Severe Hypokalemia with Primary Aldosteronism: A Case Report and Literature Review.

    Hirose R, Tsurutani Y, Nakatsue T, et al.

    Internal medicine (Tokyo, Japan) 2024; (63(10)):1405-1413 doi:10.2169/internalmedicine.1931-23.

    PMID: 37813618
  8. 8

    Prevalence of Primary Aldosteronism in Newly Diagnosed Hypertensive Patients in Primary Care.

    Asbach E, Kellnar A, Bekeran M, et al.

    Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association 2022; (130(12)):801-805 doi:10.1055/a-1938-4242.

    PMID: 36070803
  9. 9

    Aldosterone and Cardiovascular Risk Across the Lifespan.

    Ananda RA, Mori TA, Yang J

    Metabolites 2025; (15(8)) doi:10.3390/metabo15080553.

    PMID: 40863169
  10. 10

    Familial hyperaldosteronism: an European Reference Network on Rare Endocrine Conditions clinical practice guideline.

    Mulatero P, Scholl UI, Fardella CE, et al.

    European journal of endocrinology 2024; (190(4)):G1-G14 doi:10.1093/ejendo/lvae041.

    PMID: 38571460
  11. 11

    Taiwan mini-frontier of primary aldosteronism: Updating treatment and comorbidities detection.

    Chan CK, Chang YY, Tsai YC, et al.

    Journal of the Formosan Medical Association = Taiwan yi zhi 2021; (120(10)):1811-1820 doi:10.1016/j.jfma.2021.03.032.

    PMID: 33906783
  12. 12

    Treatment of Primary Aldosteronism.

    Parisien-La Salle S, Hundemer GL, Nehs MA, et al.

    Hypertension (Dallas, Tex. : 1979) 2026; (83(5)):e26238 doi:10.1161/HYPERTENSIONAHA.126.26238.

    PMID: 41808633
  13. 13

    Cardiometabolic outcomes and mortality in medically treated primary aldosteronism: a retrospective cohort study.

    Hundemer GL, Curhan GC, Yozamp N, et al.

    The lancet. Diabetes & endocrinology 2018; (6(1)):51-59 doi:10.1016/S2213-8587(17)30367-4.

    PMID: 29129576
  14. 14

    Incidence of Atrial Fibrillation and Mineralocorticoid Receptor Activity in Patients With Medically and Surgically Treated Primary Aldosteronism.

    Hundemer GL, Curhan GC, Yozamp N, et al.

    JAMA cardiology 2018; (3(8)):768-774 doi:10.1001/jamacardio.2018.2003.

    PMID: 30027227

This page explains FH-II, including inherited causes, family testing, and long-term treatment, for informational purposes only and does not constitute medical advice. Do not change blood pressure or potassium medicines without guidance from your healthcare team.