Blood tests – Morphology


Blood is a very important component of the human body. It makes up about 7% of the body weight, so in an adult it corresponds to 5 liters. Most of the blood is plasma (55% by volume). The most important function of blood is to supply oxygen, hormones, nutrients and enzymes to every cell in the body.

Blood tests - Morphology

In addition, blood transports such substances as sugars, proteins,
immunoglobulins (proteins responsible for the body’s immunity), amino acids, lipoproteins (combinations of proteins and fats), triglycerides, vitamins, minerals, waste products such as CO2, urea, and others: CO2, urea and others. Blood also protects the body against the entry of pathogenic microorganisms into the body. Thanks to its coagulability, it takes part in the healing of wounds.

The blood consists of:

  • red blood cells – erythrocytes
  • white blood cells – leukocytes
  • platelets – thrombocytes
  • plasma – the liquid part of blood.

Tests of individual blood parameters significantly facilitate the diagnosis of many diseases. They provide information on the functioning of almost all organs of the body. They also allow the appropriate selection of drugs for a given disease.

Once you have gone through the blood draw procedure, all you have to do is wait for the blood test results, which are usually available within a few hours – for basic determinations. With the results you should go to the doctor in charge even if none of the norms was exceeded. It is worthwhile for the specialist to have an overview of the results in order to prevent illnesses. With the help of the blood count it is possible to practically exclude or confirm infections, pregnancy, anemia, inflammatory conditions, cancer or drug overdose.

When do we do blood count?

It is worth noting that every adult person should prophylactically perform a blood count at least once a year, even if nothing ails him. It happens that some diseases are visible in the blood picture at the beginning, and only after some time their symptoms become physically noticeable to us. The old rule says that ‘prevention is better than cure’, so it is possible to prevent the development of the disease if it can be diagnosed during the blood test. And if the disease process has already begun, but the examined person has not yet directly felt its effects, there is a chance for faster and more effective treatment than in the case of a disease already developed in the body.

It should also be mentioned here that the prophylactic blood test is performed only by adults, while children undergo a basic blood test on the express recommendation of the doctor, when we see that something worrying is happening with the health of a child. However, if we perform a blood test because of already existing health problems, this test can be performed privately – then we do not need a referral from a doctor, we simply come to the facility performing the test and pay (fees for a basic blood test, i.e. blood count, are not high). Otherwise, if you want this test done free of charge, you need a referral from your doctor (there are other tests that can be done free of charge with a referral from your general practitioner).

How to prepare for a blood count?

It is obvious that in order to obtain a reliable blood count result, it is not possible to come for the examination ‘on the spur of the moment’. It is important to prepare the examined person, which begins 24 hours before the scheduled blood sampling. The first important rule – blood is usually taken in the morning hours. Why? First of all, because in the morning the levels of individual blood indicators are the most reliable. In addition, a person should go for a blood test on an empty stomach, i.e. at least 6 hours after the last meal.

Therefore, it is best to perform a blood count first thing in the morning. Immediately before the test you should not do any physical activity – it is advisable to plan your journey to the blood collection centre in advance in order to avoid strenuous running, which may significantly affect e.g. your white blood cell count and thus falsify the result of the blood count. As far as food and drinks are concerned, only non-carbonated mineral water is allowed to be drunk at least 6 hours before the blood sample is taken.

It is also advisable to limit very fatty and/or sugary foods even 24 hours prior to a blood draw. You should not limit the amount of food, but only take care of the quality. The same applies to alcohol – the day before the blood test it is best not to consume alcohol at all. Immediately before the examination it is also advisable to inform the person performing the test if you are sensitive to the sight of blood or if you have previously had episodes of fainting during a blood draw. This will avoid unnecessary stress for both the person being examined and the examiner.

What does a blood test look like – blood count?

Now that we know why a blood test is performed, let’s trace its course. Blood morphology is performed in specialized institutions (hospitals, clinics, laboratories) by people and equipment qualified in this field. After registration and verification of identity, the examined person sits in a chair (people sensitive to the sight of blood can lie down) and the person taking the blood puts a tourniquet on top of the limb from which the blood is taken – usually this is the hand, and the blood is taken from the vein in the elbow bend. The subject is asked to straighten his or her arm and clench his or her fist to better visualize the vein. The examination person disinfects the site of injection (e.g. with ethyl alcohol solution), stretches the skin of the examined person, and inserts the needle into the vein. He or she also releases the pressure of the bandage. Blood may be drawn with a syringe, or it may drip directly into a tube. Once enough blood has been drawn, the examiner withdraws the needle from the vein and the subject is asked to press a sterile gauze pad firmly against the puncture site. This is to prevent hematoma formation at the puncture site. For this reason you should also not bend your elbow, but keep your arm straight for a few minutes. The test is over – now you only have to wait for the results – you can do it in person, usually the same day. An increasingly popular form of obtaining blood test results is their receipt in electronic form, after logging into the appropriate panel on the website of the facility performing the test. All information can be obtained at the facility where the blood test is performed.


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