Triglycerides are fat molecules that circulate in the blood. High levels of these fats are often associated with high levels of LDL, or 'bad,' cholesterol and low levels of HDL, or 'good,' cholesterol. Normal triglyceride levels are those below 150 milligrams per deciliter (mg/dL), which is also sometimes measured as 1.7 millimole/liter (mmol/L). Levels higher than that can pose a risk factor for heart disease or diabetes.
Groups such as the American Heart Association advise that anyone over 20 years of age should get blood work done to measure triglyceride and cholesterol levels. Only one sample of blood needs to be drawn for various tests. A person undergoing such tests should fast overnight before the blood is drawn. Typically, eight hours is considered adequate time to fast. False high readings are a common problem with the measurement of triglyceride levels, and several factors can interfere with obtaining measurements of a person’s normal triglyceride levels.
For instance, consuming a rich meal can temporarily increase triglyceride levels in the blood. It can take longer than eight hours to metabolize all of the fat in some cases. Thus, it is now advised to fast for 14 hours before having blood drawn for triglyceride testing. Also, one should avoid alcohol for at least 24 hours in advance, since it can cause a substantial transient increase in triglyceride levels. Vitamin supplements are another item to be avoided for 24 hours before this test.
Borderline high levels of triglycerides are generally considered to range from 150 to 199 mg/dL (1.7 to 2.25 mmol/L). These high levels frequently coincide with high levels of undesirable cholesterol (LDL) and low levels of desirable cholesterol (HDL). This can make it difficult to sort out exactly which component of the increased lipids contributes to increased risks of heart disease and stroke, due to the elevated levels of triglycerides.
There are different standards of triglyceride levels for each gender. Women should have a lower level of triglycerides in their blood than men. One estimate sets female normal triglyceride levels at 82.5% lower than that of men. This would make women's desired level 124 mg/dL (1.4 mmol/L), if one adheres to American Heart Association standards.
While normal triglyceride levels have traditionally been targeted at less than 150 mg/dL (1.7 mmol/L), there are some medical experts who feel that this is too high. These people believe that, while this value is normal, it includes a proportion of people who are unhealthy. Other health professionals consider levels above 100 mg/dL (1.1 mmol/L) to contribute to risks for heart problems and diabetes.