Blood normally contains 150 milligrams of triglycerides or less per deciliter, according to Mayo Clinic. Levels closer to 100 milligrams per deciliter are better for heart health. A blood test performed after fasting for 8 to 12 hours assesses triglyceride levels, states MedlinePlus.
Triglycerides are necessary, but excess amounts in the blood increase the risk of heart disease, says MedlinePlus. Triglyceride levels between 150 and 199 milligrams per deciliter are borderline high. Levels between 200 and 499 milligrams per deciliter fall into the high range, while anything above 500 milligrams per deciliter is very high. High triglyceride levels often occur with other risk factors, such as high cholesterol levels and type 2 diabetes.