Diagnosis

A detailed family history is an important key to diagnosing familial hypercholesterolemia. Doctors will be interested to know if your siblings, parents, aunts, uncles or grandparents ever had high cholesterol levels or heart disease — especially during childhood.

During the physical exam, doctors usually check for cholesterol deposits that may occur in the skin around the hands, knees, elbows and eyes. Tendons in the heel and hand may be thickened, and a gray or white ring may develop around the iris of the eye.

Cholesterol tests

The National Heart, Lung, and Blood Institute recommends that a person's first cholesterol screening should occur between the ages of 9 and 11, and then be repeated every five years after that. Earlier or more-frequent screenings may be suggested for families with a history of childhood heart disease.

In the United States, cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood. In Canada and many European countries, cholesterol levels are measured in millimoles per liter (mmol/L).

Adults who have familial hypercholesterolemia usually have LDL cholesterol levels over 190 mg/dL (4.9 mmol/L). Children who have the disorder often have LDL cholesterol levels over 160 mg/dL (4.1 mmol/L). In severe cases, LDL cholesterol levels can be over 500 mg/dL (13 mmol/L).

LDL cholesterol is also known as bad cholesterol because it can build up in the walls of the arteries, making them hard and narrow. This can increase the risk of heart attacks.

Genetic testing

A genetic test can confirm familial hypercholesterolemia, but it's not always necessary. However, a genetic test can help determine whether other family members also may be at risk.

If one parent has familial hypercholesterolemia, each child has a 50% chance of inheriting it. Inheriting the altered gene from both parents can result in a rarer and more severe form of the disease.

If you are diagnosed with familial hypercholesterolemia, doctors usually recommend that your first-degree relatives — such as siblings, parents and children — be checked for the disorder. This will allow treatment to begin early, if needed.