Can't eat for a few hours before the blood test?

The fasting standard is: if you want to draw blood at 8: 00 in the morning, don't eat after 8: 00 the night before. It is best to draw blood on an empty stomach between 7: 30 and 8: 30 in the morning. Many people draw blood after 10, which easily leads to blood sugar distortion.

Taking triglycerides as an example, the triglyceride concentration reaches its peak 2-4 hours after meals, but it will basically return to the fasting level after 8 hours. Because the individual's metabolic ability is different, it is best to test it again on an empty stomach 10~ 12 hours. However, the fasting time should not be too long. Once the fat stored in the body is "mobilized", the triglyceride concentration will also increase. At the same time, serum bilirubin may increase and blood sugar may decrease.

Stress and emotional excitement can affect neuroendocrine function, leading to the increase of serum non-esterified fatty acids, lactic acid and blood sugar. Therefore, before the physical examination, you should control your emotions, keep your emotions stable before the exam, don't walk around, don't eat cold drinks, and don't smoke.

Extended data:

Taboos before physical examination:

1 to avoid drawing blood too late:

During the day, people's metabolism always fluctuates, and the metabolic rate is not at the same level. Therefore, the physical examination requires blood to be drawn on an empty stomach at 7: 30 ~ 8: 30 in the morning, and it cannot exceed 12: 00 at the latest. It's too late, because of the influence of physiological endocrine hormones in the body, the test value will be distorted.

2. Avoid strenuous exercise:

Exercise will cause changes in blood and body fluid components, even a slight activity will lead to an increase in physiological blood sugar and changes in endocrine hormone levels, thus affecting performance. So don't do strenuous exercise two days before physical examination, and don't do light activities such as walking before 1 hour.

3, avoid greasy diet:

Diet is the most important factor affecting blood lipids. Blood lipids should be checked after fasting 12 hours. Generally, after dinner, don't eat other food except water. In addition, in order to ensure the objective and accurate results of the physical examination, the subjects must eat less or not eat high-fat food and drink alcohol within 3 days before the physical examination.

4. Avoid the physiological period:

Women's menstrual period, pregnancy and other physiological conditions will affect the blood test results, so women should not do gynecological examination, blood routine examination and liver function examination before and after menstruation. Breast infrared examination is also best chosen one week after menstruation is clean.

5, avoid blind withdrawal:

Blood collection should be on an empty stomach, but patients with chronic diseases should be treated differently. For example, some patients with hypertension have to take antihypertensive drugs every morning. Stopping drugs or delaying taking drugs rashly will lead to a sharp rise in blood pressure, which is dangerous. Therefore, patients with hypertension should take antihypertensive drugs as usual before receiving physical examination. If you are taking antibiotics, vitamin C and diet pills, you should wait for 3 days after stopping taking them.

People's Daily Online-There are 7 taboos about fasting too much and drawing blood too late before physical examination.

People's Network-Does the physical examination need an empty stomach? Remember the precautions before physical examination.