Physical examination tips: What is considered fasting? How long should you be “fasting”?

Author: Chu Xi, Chief Physician, Xuanwu Hospital, Capital Medical University

Reviewer: Zhang Haicheng, Chief Physician, Peking University People's Hospital

As we all know, physical examinations require blood draws on an empty stomach, but many people are unclear about what fasting means.

1. How long without eating is considered fasting?

Physical examinations are usually scheduled in the morning, that is, the examinee gets up in the morning and goes to the hospital for a blood test without eating.

Generally speaking, blood drawing in the morning on an empty stomach requires fasting for at least 8 hours, preferably 12-14 hours, but it is not recommended to exceed 16 hours.

Therefore, if you go to the hospital for a blood test at 8 o'clock the next morning, you should not eat after 8 o'clock the night before.

Figure 1 Original copyright image, no permission to reprint

Different from the traditional concept, you cannot drink a lot of water during the fasting period, but you can drink a small amount of water if there is special need.

For example, for those with high blood pressure, if they need to take antihypertensive drugs on the morning of the examination, they can take them with a small amount of water, but it is recommended that the amount of water should not exceed 100 ml.

It is important to remind you that hypoglycemic drugs are usually taken before or during meals, and they mainly lower blood sugar by promoting insulin secretion. Since you are fasting on the morning of the physical examination, you cannot take hypoglycemic drugs to avoid hypoglycemia. Instead, you should take hypoglycemic drugs after checking the fasting items and before or during meals.

2. What should you pay attention to in your diet the day before a physical examination?

It is generally recommended not to eat high-calorie or high-fat foods or drinks one day or three days before the physical examination to avoid affecting the physical examination results. If you eat a lot of sweets such as milk tea, candied fruit, etc. one day before the physical examination, it will produce a lot of calories and may affect the blood sugar results.

In addition, foods such as large amounts of fish, meat, fried chicken, barbecue, etc. may affect the levels of triglycerides in the blood.

In addition, do not eat high-purine foods before the physical examination, such as seafood, hot pot, beef and mutton broth, etc. These high-purine foods may affect the results of blood uric acid.

Some foods such as animal blood (such as duck blood), or vegetables with high chlorophyll content (spinach, amaranth, etc.), or certain medicines such as iron-containing medicines may cause false positive results in fecal occult blood tests. Try to avoid eating or taking them before a physical examination.

In short, you should eat a light diet before a physical examination.

3. What examination items are generally included in the physical examination?

Physical examination items may include basic items and optional items. Basic items are some items that must be checked in the physical examination, such as questionnaires, physical examinations, basic laboratory tests, chest X-rays, electrocardiograms, abdominal B-ultrasound, etc. Optional items are some other items added on the basis of basic items according to each person's different health conditions.

The purpose of basic examination is to understand the basic health status of the body, including the following categories:

The first part is the health questionnaire. Many physical examination centers or physical examination personnel may not pay much attention to the questionnaire. In fact, through the questionnaire, we can understand the physical examination person's living habits, previous medical history, family history, personal history, and surgical history. This information is very important for analyzing the results of the entire physical examination report.

The second part is the physical examination. The physical examination includes general examinations, such as height, weight, waist circumference, abdominal circumference, blood pressure and other items. In addition, it also includes physical examinations, which are several basic departments that must be checked in the physical examination, such as internal medicine, surgery, ophthalmology, otolaryngology, dentistry, and gynecological examinations for women. Each department has corresponding basic examination content.

The third part is laboratory examination, which is what we call chemical examination, including blood test, urine test, stool test, cytological examination, and some marker examination.

The fourth part is imaging examination, such as chest X-ray or CT, as well as various B-ultrasound, electrocardiogram examinations, etc.

Figure 2 Original copyright image, no permission to reprint

In addition to the basic items of health check-up, there are also some optional items. Depending on each person's basic health condition, medical history, family history of tumors or cardiovascular diseases, etc., as well as personal financial situation, the optional physical examination items are different.

Make a comprehensive analysis based on the above situation, and then choose the physical examination items that suit you, so as to have a more comprehensive understanding of your health status.