An article in a recent issue of the British Medical Journal warns physicians that those people at greatest risk for heart attack may have dangerously high blood levels of cholesterol and not even be aware of it. Familial hypercholesterolemia is an inherited disorder marked by lifelong elevated levels of blood cholesterol. Left untreated, up to one-half of men and one-third of women with this condition will suffer a heart attack.

In an attempt to determine the scope of this problem, researchers in England examined the medical records of people thought to have a family history of high cholesterol. People were considered to be at high risk for familial hypercholesterolemia if they had a total cholesterol level greater than 7.5 mmol/l (equal to 276 mg/dl in American measurements) or an LDL cholesterol level greater than 4.9 mmol/l (equal to 180 mg/dl in American measurements). Researchers also checked the medical records for mention of tendon xanthomas, which are painful nodules or deposits commonly found in or near the joints of those with familial hypercholesterolemia.

The researchers then compared the number of people known to have an inherited tendency toward high cholesterol with the number of people they would expect to see given the estimated occurrence of one in every 500 people. They found that only 25% of the cases had been detected through routine medical care, and most of those people were identified in middle-age, after years of high cholesterol levels had damaged their blood vessels.

Prompt treatment aimed at controlling high blood cholesterol levels can decrease or delay the development of heart disease. For some people with familial hypercholesterolemia, a low-fat, low-cholesterol diet and drug therapy are enough to keep elevated cholesterol levels under control. Others with a more severe form of this condition are treated with a procedure that "cleans" their blood of excess LDL cholesterol.

The authors of this study say that early detection is the key to successfully treating people with familial hypercholesterolemia, but few healthcare systems are equipped to test everyone--especially young, apparently healthy individuals-- for high cholesterol levels. They say that a more practical approach would be to encourage testing of those with a family history of early onset heart disease. Middle-aged and older people who have battled high cholesterol levels for years may want to encourage younger family members to have their blood cholesterol levels tested, since those who catch the condition early stand the best chance of staying "heart healthy."