Familial hyperaldosteronism type IV: A Patient Guide

Familial Hyperaldosteronism Type IV (FH4) is an exceptionally rare genetic condition that fundamentally changes how the body regulates blood pressure and mineral balance. At its core, FH4 is a disorder of the adrenal glands, the two small organs that sit atop the kidneys and produce essential hormones. In people with this condition, a specific genetic change—a pathogenic or likely pathogenic germline variant in the CACNA1H gene—causes these glands to produce an excessive, inappropriately regulated supply of aldosterone ^[1]. This hormone acts to tell the kidneys to hold onto salt and flush out potassium, a combination that forces blood pressure to rise, often starting in early childhood ^[2].

Because the root cause is a germline variant present in the DNA of every cell, the adrenal glands overproduce aldosterone regardless of the body’s actual needs ^[3]. This is why the condition typically appears much earlier than common forms of high blood pressure, frequently being identified in children before the age of ten ^[4]. While some children may experience muscle weakness or fatigue due to low potassium levels, others may appear completely healthy despite having high blood pressure ^[2]. This variability makes a precise diagnosis through genetic testing essential, as the symptoms alone can look like many other more common childhood illnesses. A Variant of Uncertain Significance (VUS) is not enough to confirm the disease.

Understanding that FH4 is a systemic genetic issue is the most important factor in choosing the right treatment. In many other adrenal disorders, surgery to remove a single gland can provide a cure; however, in FH4, this approach is generally avoided without specialist review and functional localization ^[2]. Because the altered calcium channels are present in both adrenal glands, removing one usually fails to stop the overproduction of hormones, and high blood pressure often returns quickly. Instead, the standard of care is lifelong medical management using medications called mineralocorticoid receptor antagonists (MRAs), such as spironolactone or eplerenone, which act to block the extra aldosterone from affecting the body ^[2][5].

Living with FH4 requires a partnership between the family and a specialized medical team to monitor blood pressure, kidney function, and hormone levels as a child grows. Because the condition is inherited in an autosomal dominant pattern, if a parent has the pathogenic variant, each pregnancy has a 50% chance of inheriting it ^[2][3]. Identifying these family members through cascade screening allows them to begin monitoring early, protecting them from the long-term silent damage that untreated high blood pressure can cause. With the right combination of medication and a low-sodium lifestyle, children with FH4 can manage their condition effectively and live healthy, active lives.