You've probably heard someone say, "Let's do a blood test" when you go to see a doctor. Sometimes it's for a routine checkup, sometimes it's for a medical condition. So what is a blood test? Why is it so important? Many people are a little scared and nervous about it. But it's actually a very important thing that helps the doctor find out what's going on inside your body. Let's talk about it simply and clearly.
Why do we need to do a blood test?
The blood in your body is like a storehouse of information. It can tell you a lot about your health. There are several reasons why a doctor might ask you to have a blood test.
- Routine Checkup: During a routine checkup, like your annual checkup, your doctor may order a blood test to make sure everything is okay. This can give you a general idea of the cells in your blood, sugar, and many other things.
- Screening Tests: If there is a risk of developing certain diseases, such as diabetes or heart disease, blood tests are performed to determine whether that risk exists before symptoms appear.
- When you feel sick: If you have symptoms of an illness (fever, body aches, fatigue), a blood test can help determine the exact cause. For example, if a pregnant woman has symptoms, a blood test to check hormone levels can be done to confirm the diagnosis.
- Check if the treatment is effective: If you are taking medication for an illness, your doctor will order blood tests from time to time to see if the medication is working properly and if the illness is getting better.
- Learn about genetic conditions: Some diseases can be caused by genetic changes that are passed down through generations. In these cases, a blood sample will be taken to see if you have the genetic condition.
What does a blood test actually show?
Simply put, a blood test gives you a glimpse of what's going on inside your body. It's like taking a snapshot of what's going on inside your body at that moment. But remember, the results of a blood test are not a diagnosis. They are just important clues that help your doctor find the cause of your illness. Just because a value in your report is slightly higher or lower than normal doesn't necessarily mean you have a serious illness.
With a blood test, the doctor will mainly focus on things like:
- How well your blood is working: For example, your red blood cells are what carry oxygen throughout your body. If a blood test shows that your red blood cell count is low, it could be anemia.
- Enzyme and Electrolyte Levels: Enzymes are proteins that speed up chemical reactions in our bodies. Electrolytes are minerals like sodium and potassium. Changes in their levels can give us an idea of how organs like the kidneys and liver are functioning.
What are the main blood tests that are most often performed?
There are many types of blood tests. Some of them look at several things at once. Some of them look at only one thing. Let's look at some of the tests that we do regularly.
Complete Blood Count (CBC)
This is the most common blood test. Some people also call it a `Full Blood Count`. It mainly looks at:
- The number and status of your red blood cells (RBC) , white blood cells (WBC) , and platelets .
- Hemoglobin level. This is often used to determine if there is a lack of blood in the body (anemia).
- Information about the size and shape of red blood cells.
A CBC test can give you an idea of many common things, such as whether you have an infection or anemia.
Metabolic Panels
This looks at the different chemicals in your blood. It can tell you about the function of organs like your kidneys and liver and the balance in your body. There are two types of this:
1. Basic Metabolic Panel (BMP): Includes some basic tests.
2. Comprehensive Metabolic Panel (CMP): Includes several more tests than the BMP.
The table below lists some of the things these tests look at.
| Test Name | What it Checks? |
|---|---|
| Glucose | Blood sugar level. To diagnose diabetes. |
| Calcium | A mineral essential for the functioning of bones, heart, and nerves. |
| BUN and Creatinine | Check the functioning of the kidneys and whether they are filtering waste properly. |
| Sodium, Potassium, Chloride (Electrolytes) | To maintain fluid and acid-base balance in the body. |
| ALT, AST, ALP | These are liver enzymes. Their levels tell us about the health of the liver. |
| Bilirubin | A substance produced by the liver. An increase in this may indicate a problem with the liver or gallbladder. |
Types of tests used to detect specific diseases
In addition to the general tests mentioned above, if there is suspicion of a specific disease, specific tests related to that disease are also performed.
For cancer
If cancer is suspected or during treatment, your doctor may order special tests.
- Tumor Markers: These are substances produced by cancer cells or by normal cells in the body in response to cancer. Examples:
- PSA: for prostate cancer.
- CA-125: For ovarian cancer.
- CEA: For various types of cancer.
- Fecal Occult Blood Test (FOBT): This is done if colon cancer is suspected.
- Urinalysis: Checks for blood cells in the urine.
For Heart Disease
There are specific blood tests that can be used to check for heart disease or heart conditions. These are also called cardiac markers .
Endocrine System Disorders
This is a hormone-related disease.
- Blood Glucose and A1C: To diagnose and manage diabetes.
- Thyroid hormone test (TSH): Checks thyroid function.
How do you prepare before a blood test?
This will vary depending on the test you have, so always seek advice from your doctor or lab.
- Fasting: For some tests, such as fasting blood sugar and lipid profile, you may be asked to fast for 8-12 hours. It is usually okay to drink a little water. But be sure to ask about this.
- Drink plenty of water: If you have a test that doesn't require you to fast, drink plenty of water before donating blood. This will make it easier to find the vein.
- Apply a moisturizer: If the skin on your hands is dry, applying a moisturizer can sometimes make it easier to insert the needle.
- Light exercise: Doing something like walking around before donating blood can increase blood circulation and make it easier to find a vein.
What happens when blood is drawn?
There is a person who is specially trained to draw blood, they are called ``Phlebotomists``. This process happens like this:
1. You will be seated in a chair and asked to place a table on top of it so that you can stretch out your arms.
2. If you are wearing a long-sleeved shirt, you will be asked to raise your arms above your elbow.
3. The area where the blood will be drawn will be cleaned with an antiseptic, and an elastic band (tourniquet) will be applied to the upper arm. You may also be asked to squeeze your arm to help the veins stand out better.
4. Then, very quickly, a small needle is inserted into the vein. This is called a ``Venipuncture''. You may feel a slight stinging sensation.
5. Collect the required amount of blood into the tubes attached to the lancet. Depending on the type of test, more than one tube may be required.
6. Once the blood is drawn, the elastic band is removed, the needle is taken out, a piece of cotton is placed in the area, and a plaster is applied.
Are you scared of having blood drawn? Here are some things you can do
It's normal for many people to feel a little nervous or anxious about donating blood. If that's the case for you, try these things:
- Understand the reason: Ask your doctor why this test is being done and what it will look for. This will help reduce your fear.
- Take a deep breath: When inserting the needle, take a slow, deep breath and exhale.
- Look the other way: If you're afraid to look at the thorn, look the other way.
- Distract yourself: Do something like mentally counting to 10 or remembering a favorite song.
After the test... let's know about the report.
After the blood is drawn, leave the bandage on for a few hours. The time it takes for the results to come back varies depending on the test. Some tests take a few hours to get results, while others, such as genetic tests, can take days.
The most important thing is, don't be afraid of retaliation if the doctor says he wants to talk to you about the report. It doesn't always mean something bad. Maybe he's explaining normal results, or maybe he's talking about ways to improve your health.
Don't jump to conclusions based on a blood test report. Only your doctor can accurately understand the values and explain them in relation to your health condition.
Take-Home Message
- Blood tests are a very important and common tool that doctors use to learn about your health.
- Just because a blood test result is outside the normal range doesn't mean it's a serious illness. It's only one part of the whole picture.
- If you receive instructions such as fasting before the test, follow them exactly.
- Don't be afraid to ask your doctor about anything you don't understand, whether it's about the test or the results.
- Never interpret a blood report on your own. Always discuss it with your doctor.
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