Blood on an empty stomach. What can you eat and drink before a blood test. General blood test: on an empty stomach or not

General analysis blood test is the easiest and most informative way to find out about your health status. At the same time, it is not necessary to be sick; you can donate biomaterial for prevention purposes. How seriously we approach the issue of preparing for the study depends on its result.

It seems that there is nothing complicated in the process: I got up early in the morning and went to the laboratory. However, the most frequently asked question in patients is the following: "How to take a complete blood count: on an empty stomach or not?" This fact worries many for a reason: after all, a child is unlikely to endure hunger, and a pregnant woman suffering from toxicosis can aggravate an already unenviable state of health.

A few words about analysis

A clinical blood test is a study that is long and long years is the main way to determine the state of all body systems. It shows how all the processes in the body proceed and can reveal hidden pathologies at an early stage.

A complete blood count (sometimes we will call it CBC) is a kind of starting point in identifying the disease and prescribing the appropriate treatment. Just imagine how many liters of blood we would need to donate if the doctor ordered an analysis for each disease or malfunction of any system each time separately. Pledge successful diagnosis lies in the results of the general analysis. If the doctor finds something wrong, a more extensive examination is prescribed.

General analysis shows how the main shaped elements blood: erythrocytes, leukocytes, platelets. The laboratory assistant counts their number, determines the size, calculates the erythrocyte sedimentation rate, or scientifically ESR.

Let's try to delve a little deeper into the composition of the fluid that flows in our veins.

Most of all in it are erythrocytes - red bodies, which give our blood the corresponding color. So many of them that a general blood test determines them as a huge number with twelve zeros. The main supplier of these cells is Bone marrow. Tirelessly, he produces in the amount of 2.4 million every second.
Platelets are the main ones for clotting. Too much liquid blood- a high risk of bleeding even with the slightest damage, thick - the risk of blood clots.
Leukocytes are the guardians of our health. All sorts of viruses, infections, fungi first meet with "defenders" and many of them no longer reach the goal with their sabotage.

UAC, examining blood elements, reflects the work of almost all body systems, which increases the chances of high-quality diagnosis and treatment at times.

How to prepare the body before the study

In order not to be disappointed in the results obtained and not to go for a second blood donation, doctors advise you to follow a number of recommendations before the study.

Medical documentation provides for a certain time for a consultation, which includes a story about the rules for passing laboratory tests. But in reality, the doctor does not have time to tell everything, so you have to turn to other sources.

Stop smoking a couple of hours before going to the lab. The nicotine will cause the blood vessels to constrict, making it difficult for blood to flow out.
Before the procedure, it is better not to drink strong tea and coffee.
Give up fatty foods don't sing alcoholic drinks. This will increase cholesterol levels and affect the erythrocyte sedimentation rate.
Refuse for a while from taking drugs that affect blood clotting. There is no such possibility - warn the attending physician and laboratory assistant.
During a viral or infectious disease, you should not donate blood. The results will be reliable only after seven days after recovery.

We must not forget that external factors may also affect test results. So, for example, on the eve you should not get too carried away with physical activity. You will receive a release of certain hormones into the blood, which will easily blur the true clinical picture.

If before the analysis you performed various “internal” interventions, gastroscopy, dental surgery, colonoscopy, then the biomaterial will most likely show increased content leukocytes. Therefore, it is necessary to wait a week after the procedure and only then go to the laboratory.

Incorrect transport is often the cause of false results.

To be sure of the result of the analysis, take it to one laboratory. Different clinics may have different reagents. You have been assigned a control analysis - take it where the previous ones were taken.

On an empty stomach or not? That's the question…

Sometimes the doctor forgets to say the most important thing: how do they generally take a general blood test - is it necessary on an empty stomach or not?

These disputes cause a lot of bewilderment among the population: how the food eaten before the analysis will affect its results. By the way, the doctors themselves cannot agree on a single opinion: some say that it is necessary on an empty stomach, others argue that a hungry pause of 3-4 hours is enough.

Immediately it is worth deciding on the concept of "on an empty stomach." This does not mean that you need to starve all day the day before, and then go to the laboratory exhausted and hungry. It's not all that scary. Have a good dinner, excluding any harmfulness, get enough sleep, get up early in the morning, cut sandwiches and put them in your bag. Donate blood - start eating. In this case, you will ideally fulfill the requirement "on an empty stomach".

We will take the traditional opinion of the majority medical workers: to avoid possible misunderstandings in the results of the study, blood should be donated on an empty stomach, observing a twelve-hour pause between meals.

However, this requirement cannot be considered strict. The thing is that the KLA examines the formed elements of the blood, which food cannot affect in any way. Therefore, an hour and a half before the delivery of the biomaterial, you can afford a light breakfast without butter and a variety of sausages and smoked meats, and after eating, feel free to go to the procedure.

All these conditions apply if the biomaterial in adults is taken from a finger.

If the blood is for clinical analysis you donate from a vein, which is now becoming a frequent practice, then you should refuse to eat. Even water and chewing gum are excluded.

While waiting for the baby, the load on the body increases significantly, hunger can have a negative impact on the well-being of a woman. That is why you should not take risks and experiment with your health! Pregnant women donate blood three hours after eating.

How to get tested for a child

When it comes time to donate blood to a child, any parent worries whether they donate on an empty stomach or not, whether the conditions for donating are the same for babies and older children.

In any case, preparation begins with a psychological attitude. Fear of people in white coats in the treatment room can cause crying and tantrums, which will lead to the release of hormones into the bloodstream that can change the results.

A general blood test in children is the first analysis that is prescribed in the first days of a baby's life.

Accordingly, the question arises of how to donate blood to a newborn. Of course, for babies who eat every three hours, there can be no question of any hungry pause. Blood can be taken both immediately after feeding, and a little later. It's better if it's three hours.

Children under one year old do not donate blood on an empty stomach!

If the child is more than a year old, then you should try to comply as much as possible with the requirements for preparing for the delivery of biomaterial. The kid can suffer a little and eat later - donate blood, excluding breakfast.

If the baby cannot tolerate hunger, then you should not be nervous. little man, feed him and go in 3 hours to treatment room. Your main task is to distract the child as much as possible at the time of blood sampling. So you eliminate stress and nervousness.

How older child the stricter the requirements. Obviously, a seven-year-old boy or a ten-year-old girl will be able to endure and donate blood on an empty stomach. In this case, the parents will definitely not have any doubts about the reliability of the results.

Blood tests are often done: for diseases during a trip to the hospital, when a person undergoes a planned medical checkup. The demand for such clinical trial in that it is easy to provide, and the diagnostic significance in pathologies is high. But in order to be sure of the reliability of the test for hemoglobin, antibodies, hormones, leukocytes, sugar, screening or hCG, it is important to follow the sampling technique and the correct preparation.

Laboratory blood tests

Why donate blood on an empty stomach?

Whatever blood or urine tests you decide to take, most often a prerequisite for such procedures is an examination on an empty stomach. It may seem counterintuitive to some that stomach fullness is so important when testing for HIV, syphilis, or hepatitis. But this makes sense. If you eat meat, sweets or other foods before taking blood, then the nutrients will begin to be absorbed and dissolved in the blood, affecting the volume of protein, fatty and other substances in the blood. Further, the activation of the work of enzymes occurs, the viscosity of the blood changes and the concentration of the level of hormonal molecules increases. And this involuntarily affects the state of the blood and the result of the analysis.

What tests are done on an empty stomach?

If the doctor has prescribed tests, you must follow the instructions, and not wonder how many hours you can not eat before donating blood, calculating exact time. After all, each study has its own recommendations and features.

For most blood tests important recommendation fasting fence is considered. It is better to exclude salty, peppery, fatty, fried and sweet foods. Avocados, bananas, oranges, coffee, tangerines and lemons are also on the red list of prohibited items. A person must be hungry before donating blood from a finger. Just drink some water. And then in a small amount.

Clinical (general) blood test. It is allowed to eat food for 8-12 hours. Drinking water is allowed, tea is not. If it is difficult to fast, take a light sandwich or fruit with you, then eat.

General blood analysis

Important! There are patients for whom doctors forbid for a long time starve. In this case, it is advised to eat lean porridge without sugar and butter, drink unsweetened tea.

For biochemistry. The study will determine the concentration of certain trace elements, the functional characteristics of the body. V this case it is forbidden to eat before the analysis.
For hormones. The analysis is prescribed in case of hormonal failure in the body. Recommendations for correct delivery analysis are as follows:
the day before, do not go to the sauna and bath, making heat loads on the body;
physical stress is moderate;
avoid stress and negative impact;

Instructions for donating blood on an empty stomach

if research is to be thyroid gland, it is important to completely exclude food containing iodine in three days;
you can not do an analysis when you feel bad;
clinical studies on hormones and iron are carried out until 10 am;
about admission hormonal drugs it is important to tell the attending physician;
Eliminate alcohol intake and do not smoke the day before.
For sugar. The analysis is given on an empty stomach. You can only drink water. And there is a peculiarity: in this case, you can’t even brush your teeth and chew gum. You will do everything later.
For hepatitis and other viral infections. Stop eating 6 hours before the test. Be calm and balanced. Do not smoke one hour before the procedure.
On HCG. The analysis will determine pregnancy, and is given on an empty stomach.
For tumor markers. This procedure is necessary for the detection of cancer antigens. If such a tumor marker is detected, one can speak of the appearance of a pathology - a tumor (benign or malignant). Blood from a vein is taken on an empty stomach. The answer to the question, how many hours you can’t eat a blood test: at least eight and no more than 14. If you wish, you can drink a few sips of water. Such a fence can be taken both from an adult, a child, and during pregnancy. Cancer spares no one, not even babies. Every year millions of people die from oncological pathologies on the planet.

What blood tests do patients take on a non-fasting stomach?

An analysis for the Rh factor is carried out after a clinical study of blood from a vein. The procedure is necessary to determine the blood type. Such analyzes are not given on an empty stomach. But here are the recommendations: it is important to exclude physiotherapy and X-ray examinations the day before.

Why is a blood test for donors taken on an empty stomach?

For people who decide to do a good deed and become donors, it is important to know what is prohibited in this case and how to properly prepare for blood donation. The answer to the question of whether it is necessary to donate blood on an empty stomach in this case is no. But you need to know what to eat.

For this reason, follow the rules:

The day before the procedure, do not eat fatty, salty and smoked, eggs, milk, bananas and nuts. Since the components released by these products can affect the rate of separation of blood into components. This is immediately noticeable, as the blood will be cloudy.

Poor quality cloudy plasma not suitable for transfusion

As a light breakfast can be: fruits and vegetables, sweet tea and cookies, porridge on the water.

Important! Strange as it sounds, if you pulled out a tooth or went to the dentist this year, you will not be able to become a donor. This is a ban!

Alcoholic beverages must not be drunk for 48 hours.
Three days before the procedure, you can not use aspirin and analgin. After all, these pharmaceuticals impair blood clotting.
Do not smoke for a couple of hours before blood sampling.

Important! To avoid dizziness before the procedure, it is better to drink half a liter of warm tea or plain drinking water.

Now it is known why and why a blood test is taken on an empty stomach and how long before a blood test you can not eat anything. After all, then the studied materials will show wrong results, you will not be able to find out, for example: is it sick thyroid whether there are other genetic abnormalities and other pathologies.

What can not be eaten before taking a blood test for biochemistry, sampling rules, and what threatens their non-compliance? Is it possible to drink water before going to donate blood, the influence of factors on the result

A blood test is a common method of examination. It allows you to identify a malfunction individual bodies, identify certain diseases and find out the cause of the symptoms. Before putting serious diagnosis and prescribe treatment, doctors compare the test results with the patient's state of health.

Usually, before taking the tests, the patient is warned that the procedure is carried out on an empty stomach. Neglecting this rule, the analysis may show incorrect results, and the doctor, based on them, will prescribe inappropriate treatment.

As confirmed by multiple studies, eating before taking the test can really distort its result. In some cases, food completely leads to the impossibility of performing the procedure. This is due to the fact that the nutrients that are absorbed into the blood affect the concentration of fats, proteins and other compounds in it. Also, food can activate enzyme systems and change blood viscosity. Also, nutrients increase hormonal levels, which affects the condition of the blood being studied.

As you can see, the procedure for taking a blood test is very important and you need to prepare for it, that is, do not eat for a certain time. The duration of fasting before donating blood depends on the type of analysis.

Donating blood depending on the time of the meal:

General clinical (general blood test) - taken from a finger, determines the level of hemoglobin, ESR, the number of erythrocytes, platelets and leukocytes, the results of a leukogram. After the last meal, 8 hours should pass.
Biochemical - taken from a vein, determines carbohydrates, lipids, proteins, vitamins, nitrogenous compounds. The interval from the last meal should be at least 12 hours.
Blood sugar level - taken from the finger, last appointment food 8-12 hours before analysis.
Serological (for hepatitis, syphilis, HIV) - the analysis is carried out after 8 hours from the last meal.
Tests for hormones - on an empty stomach, 5-6 hours should pass from the last meal.
Analysis for the Rh factor - food intake does not depend on the result.
Analysis for tumor markers - you will have to refrain from eating for 3-8 hours.

No big sacrifices are needed to take a blood test. In order not to have to starve on purpose, just eat in the evening, and head to the clinic in the morning. Do not neglect the recommended rules for donating blood, because your health depends on the result!

The delivery of a blood test is familiar to every person. It is a routine diagnostic method for a number of diseases. In order to get the most reliable result, you must follow the rules for preparing for the study. There are common requirements for most analyzes and individual requirements for some species.

Venous blood test

To evaluate a large number of indicators, it is venous blood that is taken. It differs from peripheral high content elements, it is easier to “recognize” it for automatic analyzers. Many laboratories use such systems.

The study of human venous blood allows you to determine the following substances in it:

hormonal compounds,
vitamin complexes,
sugar,
fats (cholesterols),
minerals and trace elements,
tumor markers,
immune antibodies,
total protein
pigments,
enzymes, etc.

Based on the data obtained as a result of the analysis of venous blood, it is possible to put big number diagnoses. For this reason, it is important to properly prepare for the study.

Why can't you eat?

A significant part of the tests that involve the collection of venous blood are taken on an empty stomach. In this case, the last meal should be no earlier than 8 hours ago. It is advisable to observe the 12-hour interval. This is due to the fact that along with food, minerals, sugars, vitamins and other compounds enter the body that can change chemical composition blood.

For example, the level of glucose after eating rises almost immediately. If at this point you explore venous blood, the result will be overestimated, a person can be given diabetes. Similarly, cholesterol levels change after eating.

Blood from a vein on an empty stomach is taken for another reason. Some reagents used by lab technicians may interact with other substances in food. The result will be false positive. Tests for infections are especially sensitive to such fluctuations. There are known cases of erroneous detection of syphilis in patients who ignored the diet on the eve of the study.

What else can not be done before the study?

There are a few more rules that must be observed before donating blood from a vein. These include:

limitation physical activity within 1-3 days before the study,
cessation of smoking and drinking alcohol for a day,
for some types of tests - sexual rest 3 days before visiting the treatment room,
when taking all women, it is mandatory to comply with the schedule menstrual cycle provided by a gynecologist,
for most of the indicators, only morning blood is suitable (collected before 10-11 o'clock), only some hormones are determined at night,
if an x-ray was taken the day before, the procedure is postponed for a day,
it is advisable to stop taking medications. Attention! This item is performed only after the approval of the attending physician,
refusal to visit baths and saunas for two days,
it is possible to determine the concentration of drugs in the blood only 2 weeks after the course of treatment,
analyzes for infectious diseases submitted at least twice.

Determination of rare, specific indicators may require compliance with other rules, which you can only ask your doctor about.

What can and cannot be drunk?

It is a well-known fact that blood is taken on an empty stomach. What other rules exist laboratory diagnostics? It is important to control not only the intake of food, but also fluids. So, on the eve of the procedure, it is better to refuse sweet tea, packaged juices, carbonated drinks, milk, mineral water, coffee. These foods significantly increase plasma levels of sugar, certain minerals, and enzymes.

Similar to food, drinks can interact with reagents and give false positive result. An unconditional rule to be observed is the refusal of alcohol. It increases the activity of liver enzymes and pancreatic compounds, sugar. In addition, alcohols lead to dehydration, which changes the performance cellular composition blood.

It is best to drink plain clean water. Immediately before sampling (1-2 hours), it is advisable to drink up to 2 glasses of water to reduce blood viscosity. This rule must be followed by those who have to fill several test tubes in one procedure.

When can you eat?

You can replenish your strength and improve your well-being immediately after blood sampling. It is recommended to drink sweet tea, have breakfast. There are no product restrictions at all. If a significant amount of blood has been donated, then during the day it is advisable to use a large number of liquids. In addition, these patients are shown bed rest. In most cases special recommendations on the diet are absent.