The ratio of total cholesterol to HDL cholesterol is useful for assessing risk of heart disease, according to Mayo Clinic. The higher the ratio, the more likely it is that a patient is in danger of developing a heart condition.
The ratio is determined by dividing the total cholesterol number by the "good" HDL cholesterol result, Mayo Clinic explains. Total cholesterol is a combination of HDL and LDL cholesterol levels plus 20 percent of the triglycerides score, states Healthline. The ideal is a ratio of 3.5-to-1, although 5-to-1 or less is acceptable. For men, a ratio of 3.4 cuts the risk of heart disease in half, while a 9.6 result doubles the chances. A 3.3 score significantly lowers the risk in women, while 7 suggests heart disease is twice as likely.
This ratio, however, is not useful for determining treatment to lower the likelihood of heart disease, Mayo Clinic observes. For this, doctors use all levels: total cholesterol, HDL and LDL, which is the "bad" cholesterol. Too much LDL coats arteries with plaque, making them stiff and narrow, reports WebMD. A blood clot in the artery often leads to a heart attack or stroke. High levels of HDL are beneficial for a person's health, because HDL helps remove LDL from the bloodstream.