V. BLOOD TESTS
A. Total Cholesterol
What is a normal blood cholesterol, and when does the level produce a risk of coronary heart disease? Blood cholesterol is not necessarily very high, that is, greater than 265 mg (6.9 mmol), in those who have heart attacks. In fact, most heart attacks occur in individuals with blood cholesterol around the average of 220–250 mg (5.7–6.5 mmol). In the LIPID study described above, only 3806 men with a blood cholesterol greater than 265 mg could be found from a screening of 480,000. The remainder had cholesterol levels of less than 265 mg and most likely in the range of 200 to 250 mg.
Between 1970 and 1989, laboratories in North America reported a normal cholesterol as between 150 (3.9 mmol) and 250 (6.5 mmol). But it is now established that individuals with so-called normal cholesterol in the range of 220–250 are at increased risk, and heart attacks are common in individuals with such levels. A blood cho¬lesterol of 220–250 mg (5.7–6.5 mmol) is considered high by world standards. Most doctors now talk about an optimal safe total cholesterol level of less than 190 mg/dl (4.9 mmol/l) or LDL less than 120 mg (3 mmol). Heart attacks are uncommon in individuals with a cholesterol level less than 160 mg (4.2 mmol).