The main sign of familial hypercholesterolemia, or FH, is a number: an LDL cholesterol of 190 mg/dL or higher in an adult, usually present since youth. Add a parent, brother, sister or child with very high cholesterol or early heart disease, and FH becomes a real possibility.
FH is an inherited condition in which the body clears LDL cholesterol poorly from birth. Some people develop visible cholesterol deposits. Others have no outward sign, which is one reason the condition is so often missed.
Key takeaways
- An adult LDL cholesterol at or above 190 mg/dL is the usual trigger for asking about FH.
- Most people with LDL that high do not carry an FH gene variant, but those who do face much higher risk.
- Deposits in tendons, around the eyelids or at the edge of the cornea can point to FH.
- Ten-year risk calculators are not meant for people with LDL in this range.
- Each child of a person with FH has a one in two chance of having it, so relatives get tested.
The number that raises the question
Clinicians call an untreated LDL cholesterol of 190 mg/dL or more severe hypercholesterolemia. In a large genetic study, about 7% of US adults had LDL cholesterol that high.1
Only a small part of that group has FH in the genetic sense. When researchers sequenced the three main FH genes in people with LDL of 190 mg/dL or higher, fewer than 2% carried an FH mutation. The rest have high LDL for other reasons, and recent expert guidance stresses a thorough check for other causes before settling on FH.
Why FH is riskier than the same LDL without it
If the LDL number is the same, does the cause matter? The same study says it does. Compared with people whose LDL was under 130 mg/dL and who had no mutation, people with LDL of 190 mg/dL or higher and no mutation had about 6 times the risk of coronary artery disease. Those with LDL that high and an FH mutation had about 22 times the risk.1
The likely reason is time. A person with FH has had high LDL since childhood, so the arteries have been exposed for decades longer than a single adult blood test suggests. The researchers found that mutation carriers had higher cumulative exposure to LDL cholesterol over the years than non-carriers.
The family pattern
FH is usually inherited from one parent. Each child of a person with the common form has a 50% chance of inheriting it.2 The pattern to look for:
- A parent, sibling or child with very high LDL cholesterol, often noticed young.
- Heart attacks, stents or bypass surgery at early ages on one side of the family.
- A relative who died suddenly at a young age from a heart problem.
Our guide to family history of early heart disease explains which relatives and ages count as early. FH is one of the specific things that history can be pointing to.
Physical signs
Cholesterol that stays very high for years can settle in tissues where a doctor can see or feel it.
| Sign | What it looks like |
|---|---|
| Tendon xanthomas | Cholesterol deposits in the Achilles tendons or the tendons of the hands |
| Xanthelasma | Yellowish, waxy patches around the eyelids |
| Corneal arcus | A white, gray or blue ring at the edge of the cornea, appearing at a younger age than usual |
A standard genetics reference describes all three: xanthomas that may be visible in the Achilles tendons or hand tendons and worsen with age, deposits around the eyelids, and a corneal ring that can appear at a younger age in people with FH than in those without it.2
These are possible findings, not required ones. The blood test and the family history carry more weight.
Why risk calculators do not apply
Most people get a 10-year risk percentage before any decision about cholesterol treatment. FH is an exception. The 2018 US cholesterol guideline advised treating adults with LDL cholesterol of 190 mg/dL or higher without calculating 10-year risk at all.3
A calculator sees one cholesterol reading, not a lifetime of exposure, so it can underestimate risk in a younger adult with FH.
The same caution applies to heart scans. A coronary calcium score of zero normally supports waiting, but the 2026 US guideline lists familial hypercholesterolemia among the situations where a zero should not be read that way.4
How FH is confirmed
Diagnosis rests on three things: the LDL level, the family history and a physical exam. Clinicians combine them using formal scoring criteria. Genetic testing can confirm the diagnosis by finding a variant in one of the genes that control LDL clearance, most often LDLR, APOB or PCSK9.
Other causes of high LDL get checked along the way. Our guide on thyroid and heart risk covers one of them.
A European expert panel estimated that fewer than 1% of people with FH had been diagnosed in most countries.5 A 2026 National Lipid Association consensus puts the global prevalence at about 1 in 311 and still describes the condition as severely underdiagnosed.
Cascade testing: why relatives get checked
Because FH is passed down with a one in two chance for each child, finding one person with FH is a reason to test the family. This is called cascade testing: parents, siblings and children are checked first, then the relatives of anyone found to have it.
Relatives can be tested with a gene test when the family variant is known, or with an LDL cholesterol measurement when it is not. The 2026 National Lipid Association consensus recommends systematic cascade screening in families, along with universal cholesterol screening in childhood.6
FH is treatable, and care works best when it starts early. Which treatment fits is a decision for you and your clinician, often with a lipid specialist.
Your next step
If your LDL has been 190 mg/dL or higher, or high cholesterol and early heart disease run together in your family, raise FH by name with your doctor. Then read our guide to heart tests worth having with a family history and our chart of LDL cholesterol levels by risk.
You can also answer the three quick questions in the screener on the Cardio Res-Q program page.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
My LDL is 195. Do I have FH?
Not necessarily. In a large sequencing study, fewer than 2% of adults with LDL cholesterol of 190 mg/dL or higher carried an FH mutation. An LDL that high still deserves attention, and family history helps decide whether FH testing is worthwhile.
Can I have FH without any visible signs?
Yes. Tendon deposits, eyelid patches and an early corneal ring are possible findings, not requirements. FH is identified mainly from LDL cholesterol levels and family history, with genetic testing as confirmation.
Can a healthy diet and exercise bring FH cholesterol down to normal?
Healthy habits matter for everyone with FH, and expert guidance lists them as the first step. FH is caused by an inherited problem with clearing LDL, though, and the same guidance describes medication as part of standard care. Talk through the options with your clinician.
Should my children be tested?
If you have FH, each child has a 50% chance of having it, and expert groups recommend checking close relatives. A recent US lipid consensus also supports cholesterol screening for all children. Your child's pediatrician can advise on timing.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
