Did you know that you need to be on an empty stomach for these hematology tests?

In daily life, many examination items need to be performed on an empty stomach, especially hematology examinations, including blood sugar, glycosylated serum protein, and blood lipids. This is because eating will affect the test results, causing the test results to deviate from the actual values, which is not conducive to the doctor's judgment of the physical condition. Therefore, people must pay attention to fasting before undergoing a hematology examination.

1. Why do we need to draw blood on an empty stomach?

Since the gastrointestinal digestion and absorption activities are basically completed 12-14 hours after a meal, the various biochemical components in the blood are relatively stable. The various data measured at this time can truly reflect the physiological changes of the body and help diagnose the disease. Otherwise, if blood is drawn after eating, the test results will not be judged due to the influence of food.

1. After eating, due to digestion and absorption by the digestive system, the biochemical components in the blood, such as sugar, protein, lipids and various inorganic ions, show temporary changes. Therefore, the various results measured using this blood sample cannot reflect the true condition of the body. On the other hand, it is impossible to compare with the normal values ​​measured by fasting blood, so accurate clinical judgment cannot be obtained.

2. The serum of fasting blood is light yellow, clear and transparent. If you have eaten greasy food the night before, a large amount of chylomicrons produced after the digestion of the food will quickly enter the blood. At this time, the supernatant will be "turbid" after centrifugation, which is medically called "fatty blood" or chylomicron. Such a blood test is bound to cause a significant increase in triglycerides in the blood lipids.

3. Due to changes in the human body's biological cycle, the examination results of certain items may vary greatly depending on the time of blood collection. Fasting blood draw can help to measure at the same time, making the test results more comparable.

2. Which examination items need to be performed on an empty stomach?

1. Blood glucose and glycosylated serum protein

Fasting blood sugar level is a necessary indicator for screening diabetes. As the name suggests, this indicator reflects the level of blood sugar when fasting. Therefore, once checked after eating, it will inevitably lead to a significant increase in blood sugar, which will seriously affect the interpretation of the results and even mislead doctors to make wrong judgments. Glycated serum protein can reflect the average blood sugar level in the past 4 weeks. The result is positively correlated with blood sugar concentration and requires fasting blood. It should be noted that the fasting time should not be deliberately extended, which is medically known as super fasting. Because this can also cause low blood sugar due to excessive consumption.

2. Blood lipids

There are many factors that affect blood lipid tests, among which food has the greatest influence. Because after eating, the body's triglyceride content will increase significantly, and the enhanced fat metabolism will lead to changes in other blood lipid items such as cholesterol, high-density lipoprotein and low-density lipoprotein. Therefore, only fasting blood tests can reflect stable blood lipid levels.