Understanding Familial Hypercholesterolemia (FH)

Updated July 2026

Imagine a condition that quietly clogs your arteries from the day you are born, no matter how many salads you eat or miles you run. That is the reality for people living with familial hypercholesterolemia, or FH, a genetic disorder that keeps the body from clearing LDL cholesterol out of the blood.

FH is often invisible until something dramatic, like a heart attack, brings it to light. The good news is that screening is simple. A very high LDL level on a routine cholesterol panel, more on that below, is the first tip-off that you may have it.

What causes FH?

FH is a genetic inability to clear LDL from the blood. High LDL in general comes down to three main factors. We make too much, we clear too little, or we do not use enough. FH is a problem with clearance. A person with FH has a very hard time pulling LDL back out of circulation.

LDL is removed from the bloodstream when it attaches to receptors on your cells. The fewer of those receptors you have, or the less well they work, the higher your LDL climbs. Three genetic glitches can cause this. The most common, behind about 85 to 90 percent of cases, is a mutation in the LDLR gene, which builds the LDL receptors, so there simply are not enough of them. A second involves PCSK9, a protein that breaks down LDL receptors. Some people are born making too much of it, and their receptors get destroyed before they can do their job. The third involves ApoB, a protein that sits on every LDL particle and works like a key that locks it into the receptor. If the key is misshapen, the receptor cannot grab hold.

How common is FH, and is your high LDL actually FH?

FH is uncommon, and most high LDL is not FH at all. People often assume that because their cholesterol is high, it must be genetic, especially if it has not budged much despite some lifestyle changes. That assumption is usually wrong.

Here is the fact worth holding onto. Not all high LDL is FH, but all FH comes with very high LDL. Genetic screening studies estimate that FH affects about 1 in 250 people, which is under half a percent of the population. That means the other 99.5 percent of us have real room to move our cholesterol with strategic lifestyle change, and nutrition in particular.

FH is inherited in an autosomal dominant pattern, so if one parent has it, each child has a 50 percent chance of inheriting it.

How is FH diagnosed?

It starts with a standard cholesterol test, can be supported by physical signs, and is confirmed with genetic testing.

The cholesterol panel is the first red flag. In adults, an LDL at or above 190 mg/dL raises suspicion for FH. In children, the threshold is around 160 mg/dL. One important caveat for women. Many see their LDL jump after menopause, but a number that climbs above 190 only later in life is not FH. To point to FH, the LDL needs to have been at or above 190 for most of a person's life, including well before menopause.

Doctors can also look for physical clues of cholesterol building up in the body:

• Xanthomas, firm cholesterol deposits on the Achilles tendons or knuckles.
• Corneal arcus, a white or gray ring around the colored part of the eye, which is meaningful when it appears before age 45.
• Xanthelasma, yellowish cholesterol deposits around the eyelids.

Genetic testing is the gold standard for confirmation. It sequences the LDLR, PCSK9, and ApoB genes. Once someone is found to carry one of these markers, guidelines call for cascade testing, which means checking all first-degree relatives, parents, siblings, and children, so the condition can be caught early across the family.

How is FH treated?

Aggressively, and with a combination of medication and lifestyle. The 2026 ACC/AHA cholesterol guidelines shifted toward lower-for-longer goals to counter the damage of a lifetime of LDL exposure. For people with FH, the targets are:

• FH alone, for primary prevention: LDL under 70 mg/dL.
• FH with existing heart disease, high risk: LDL under 55 mg/dL.
• Children with FH: LDL under 100 mg/dL, with treatment sometimes starting as early as age 8 to 10.

Statins are the mainstay of treatment, even for children. When statins alone are not enough to reach the goal, the guidelines add ezetimibe and, if needed, PCSK9 inhibitors.

But there is far more you can do alongside those drugs. Lifestyle is central to every treatment plan, for anyone with high cholesterol and especially for those with FH. A heart-healthy diet and regular exercise help head off additional risk factors like obesity and high blood pressure. They also help your medications work at full strength, so you can often reach your goal on a lower dose, or on fewer drugs.

I have seen plenty of patients start with an LDL at or above 200 mg/dL and get dramatic reductions with Step One. I have also seen a low-dose statin paired with Step One produce eye-popping results. Not everyone gets a miraculous response, but you can test whether this approach delivers the impact you are hoping for. That is especially worth doing if you are young and looking at a lifetime of drug therapy.

The bottom line

FH is uncommon, but when it is present it calls for aggressive cholesterol lowering. A simple cholesterol panel is enough to screen for it, and a confirmed diagnosis should set off cascade screening of first-degree relatives. It is very treatable with a combination of medication and lifestyle. And as with every form of high cholesterol, optimizing nutrition is central to lowering the lifetime burden of medication.

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