Can blood sampling during a physical examination lead to anemia? Finally figured it out!

An essential part of every physical examination is... drawing blood!

Blood tests, also known as "blood sampling", are very important testing methods in health checkups. Why can't peripheral blood be collected when you grow up? Will blood sampling cause anemia? Why do we have to draw several tubes of blood each time?

Today, follow Ke Xiaoer to learn about blood drawing during physical examinations.

Can peripheral blood be collected from adults?

According to the "Chinese Peripheral Blood Collection Operation Consensus", peripheral blood collection is for pediatric patients under 6 years old and special adult patients, and venous blood testing should be given priority for patients over 6 years old . Compared with venous blood, peripheral blood has more influencing factors, and the collection process is not standardized, which can easily lead to variation or inaccuracy in the test results .

Mainly manifested in:

1. When peripheral blood is collected, due to the small amount of blood collected or the difficulty in bleeding, tissue fluid is easily mixed into the blood when a certain pressure is applied, causing abnormal results (increase or decrease) in certain blood routine tests.

2. The amount of peripheral blood collected is small, sometimes the sample is not sufficiently anticoagulated, or excessive squeezing of the fingers and slow blood flow produce clots, leading to a false decrease in platelets.

3. The reproducibility of peripheral blood is poor. When abnormal results require re-examination or smear testing, the amount of blood collected is often insufficient and blood needs to be drawn again.

4. Peripheral blood circulation is poor and is more affected by temperature in winter.

Therefore, except for the special circumstances mentioned above where peripheral blood needs to be collected, for adults, collecting venous blood for testing has fewer influencing factors, the results are more accurate and stable , and are more valuable for diagnosis and treatment.

Will having blood drawn cause anemia ?

Blood drawing is one of the common items in physical examinations, but some people may worry that blood drawing may cause anemia. Generally speaking, the total amount of blood in an adult's body is closely related to their body weight. The weight of blood in an adult's body accounts for about 7% to 8% of their body weight. The heavier the person, the more blood they have in their body.

An adult weighing about 70kg has about 5000mL of blood in his body. Generally, each blood collection tube requires about 2~4mL of blood, and drawing 10 tubes of blood means about 20~40mL. For an adult, this amount of blood is insignificant, and the human body can recover through self-regulation, so it will not cause anemia.

Why do we have to draw several tubes of blood each time?

Some people may think that drawing several tubes of blood each time is redundant, so why do doctors do this?

In fact, the amount of blood that needs to be drawn each time depends on the test items that need to be performed. **Different blood collection tubes represent different types of additives and test purposes, the purpose is to ensure the accuracy of the patient's test results. **Using the wrong blood collection tube or the wrong blood collection order will lead to errors or mistakes in the test results.

Physical examination is not only a kind of health protection, but also a kind of cherishing life and taking responsibility for the future. Every physical examination is an attention and care for your own health, and a responsibility and commitment to your family.

Let us start from now on, pay attention to our physical condition, have regular physical examinations, discover and deal with health problems in a timely manner, protect our health together, and build a better life together! Let health become the most moving melody in our lives, let every physical examination become our strong belief, and play the most beautiful movement for a happy tomorrow!

References:

[1] Zhao Yunna, Liu Baoxin, Ke Jingjing. Analysis of health examination results of 2 393 elderly people[J]. Chinese Journal of Urban and Rural Enterprise Health, 2024, 39(03): 40-42. DOI:10.16286/j.1003-5052. 2024. 03. 014.

[2] Liang Xinyue, Chen Xiaoxiao, Wang Liangyou, et al. Common chronic health problems and related factors of coexistence of multiple diseases among people aged ≥45 years in a community in Taizhou City[J]. Chinese Journal of Disease Control, 2024, 28(02): 233-240. DOI:10.16462/ j.cnki.zhjbkz. 2024. 02. 017.

[3] Yu Hu, Zhou Song, Huang Ying. Why are the elderly reluctant to go for physical examinations? [N]. Chongqing Daily, 2024-01-11(005). DOI:10.28120/n.cnki.ncqrb. 2024. 000396.

Science experts:

Ying Furong (Department of Laboratory, the First Affiliated Hospital of Wenzhou Medical University)

Ma Jun (Department of Pathology, the First Affiliated Hospital of Wenzhou Medical University)

Zhao Zhichao (Resident Physician, Department of Critical Care Medicine, Yuyao People's Hospital)

Chen Chen, Chen Wei (Wenzhou Medical University)