The normal value of free fatty acids is 0.3-0.9 mmol/L. It is important to fast before checking free fatty acids to avoid affecting the test results. If the test results are normal, it is important to review them regularly. Some people may have elevated or decreased levels. Elevated free fatty acid can be seen in physiological elevation, such as hunger, exercise, late pregnancy, emotional excitement, etc. In addition, there are some pathological factors that can cause its elevation: 1. Endocrine diseases: such as hyperthyroidism, diabetes; 2. Drug effects: taking caffeine, ethanol and drugs such as toluene sulfobutylurea, heparin, niacin, or after injection of epinephrine, norepinephrine, growth hormone, etc.; 3. Others: severe liver damage, myocardial infarction, obstructive jaundice, hepatitis, liver cirrhosis, etc. The decrease of free fatty acid can also be seen in physiological decrease, such as after meals, after taking glucose, etc. There are also pathological factors causing its decrease: 1. Endocrine diseases: seen in hypothyroidism, islet cell tumor, hypopituitarism, etc.; 2. Drugs: taking drugs such as aspirin, clofibrate and propranolol.