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What Are Blood Tests: What Can You Discover about Your Health?

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What are blood tests? Blood tests are used by medical practitioners to measure certain health parameters – be it proteins, vitamins, minerals, antibodies, genetic predispositions, and pathogens, for example. With these measurements, you can gain indispensable insights into your health – experts even say that the majority of medical decisions made in the United States today is based on lab test results. 

Did you know that overall, according to the Centers for Disease Control and Prevention, around 14 billion clinical lab tests are carried out every year in the United States?[1] Blood tests are considered the most common form of laboratory tests. Most of us have had a blood test at some point in our lifetime; they are routine and used to assess our general health from time to time – especially, if we are experiencing any unexplained symptoms. 

In this article, we will explore the importance of blood tests – addressing questions such as: What are blood tests (such as finger prick blood tests) and What can blood tests detect? In addition, we’ll go over the most common blood tests carried out nationwide – such as full blood count, various blood tests for heart health, and metabolic panel tests – and their purpose.

What Are Blood Tests?

Blood tests – that is, when a sample of your blood is extracted from your veins or arteries for lab analysis – are considered highly valuable in preventing or monitoring certain health conditions and diseases. Blood tests are often included as part of a regular checkup in many countries; they are carried out either by a medical practitioner or by yourself at home. Such tests are the most common type of laboratory test; other tests include urine tests, saliva tests, stool tests, and hair tests.

If your blood test reveals abnormal values or values considered to be outside the normal range, you should investigate your health further – this could be a sign of a deficiency, a disorder, or a disease. It is important to note that your blood test results could be influenced by your lifestyle – that is, by your diet, your physical activity level, alcohol or drug consumption, as well as certain medications.

Did you know that for several blood substances checked with blood tests, normal substance ranges are seen in 95 percent of healthy people, and are therefore considered a great indication of how healthy you are?[2] Normal ranges must take into consideration your gender, age, race, and various other factors – such as whether you are pregnant.

woman having blood taken for a blood test

How Does a Blood Test Work?

The majority of blood tests – whether taken at home, at your doctor’s, or at a hospital – only take a matter of minutes. After a blood test, you will usually need to wait a few days or weeks for the results. You should follow up your test results once they are available with a doctor, so you can understand them better.

These days, home tests aim to make monitoring your health easier – without necessarily needing to involve a doctor. Your results are published and sent back to you, explaining all important information in great detail. You can, of course, then opt to visit a doctor to discuss your results or next steps. 

When it comes to fasting blood tests – that is, tests where you are required to forgo eating or drinking anything but water for up to 12 hours before the test – you will be informed of whether you need to fast in advance. If you don’t follow these instructions, you could influence the results of your test.

Capillary Blood vs Venous Blood: What’s the Difference?

First things first, venous blood and capillary blood are different. Various studies have been carried out comparing the efficacy and the benefits of capillary blood compared with venous blood when it comes to diagnostic testing. While they can both be taken for blood testing, here are some differences in these types of blood.

  • Capillary blood is considered easier to collect than venous blood, as the sites of puncture include the fingertip, earlobe, heel, or big toe.
  • Capillary blood draws are more comfortable and less painful for the patient. If only a small amount of blood needs to be taken, capillary blood is preferred.
  • No doctor or phlebotomist is needed to collect capillary blood.
  • Capillary blood should be taken when the veins of patients are not accessible – for example, in older patients, newborns, obese patients, burn victims, or patients at risk of blood clots.
There are also minimal differences between capillary blood and venous blood when it comes to blood values. Capillary blood may mean that red blood cell count and hemoglobin levels, as well as leucocyte and neutrophil, may be somewhat higher in comparison with venous blood. When it comes to venous blood, however, platelet levels are higher.[3] It has also been reported that glucose, potassium, total protein, and calcium concentration are lower in capillary blood.[7]

    What Are the Various Types of Blood Tests?

    How Do You Take a Phlebotomy Blood Test?

    A phlebotomy blood test – also known as venipuncture or venous blood sampling – is a method of blood collection that involves a lab professional taking a blood sample from a vein in your arm using a needle. The practitioner collecting your blood sample may apply pressure to your arm with a tight band or ask you to form a fist with your hand. This makes it easier to draw blood and insert the needle.

    This blood is collected in a sample tube and sent off to a laboratory for analysis. This is the most common way of doing a blood test.

    What Are Finger Prick Blood Tests?

    Some blood tests are carried out by pricking your fingertip to collect a small amount of blood. These kinds of tests are called finger prick blood tests or capillary blood draws, and this method is often used for at-home health test kits and rapid tests. These are considered easy to use and require little equipment other than a lancet and a sample tube or dried blood spot card.

    Heel Stick Test: Why Is Blood Taken from the Heel?

    Heel stick tests, whereby a medical practitioner takes blood from the heel with a small needle, are predominantly performed on newborns. This method is often used for newborn health screening tests before the baby leaves the hospital – especially in intensive care units.

    Did you know that if too much blood is withdrawn from a newborn, this can lead to anemia or cardiac arrest? This is why capillary blood taken from the heel is deemed the most suitable method of collecting blood from a newborn.[7]

    What’s Best: Blood Collection Tubes or Dried Blood Spot Cards?

    A dried blood spot card is a card on which you collect a small amount of blood; this is an alternative method to collecting your blood in a sample tube. Collecting a blood sample by means of a dried blood spot card offers a few advantages over collecting your sample in a tube. 

    • A blood spot sample requires only a simple finger prick and is not painful or invasive.
    • Samples can be stored longer – they don’t need to be frozen or centrifuged.
    • Samples are more easily stored and transported.
    • Various lab analyses can be carried out with just a single drop of your blood.

    You should note that your blood sample can be spoiled in both dried spot sampling and collection tubes.

    dried blood spot card

    What Do Blood Tests Show?

    What can blood tests detect? Blood tests are very insightful and can help give you a greater idea of what is going on inside your body. They can help you, for example:

    • diagnose a disease or condition
    • monitor diseases or health conditions, such as blood sugar or cholesterol
    • check the functionality of organs, such as your heart, thyroid, kidneys, and liver
    • understand if your immune system is fighting an infection successfully
    • check for genetic health conditions

    What Are the Common Blood Tests: 5 Important Blood Tests

    Which blood tests do people require the most in the United States? As you can see, there are several different types of blood testing methods – but what about the health parameters they test? We have broken down the most common blood tests carried out in the United States, according to the National Institutes of Health; they are the full blood count test, metabolic panel test, enzyme blood test, heart health test, and the blood clotting test.

    1. What Is a Full Blood Count Test Used for?

    A complete blood count measures various parameters in your blood, such as red and white blood cell count, platelets (a cell that assists in blood clotting), hematocrit, and hemoglobin. This blood test is generally considered part of a regular checkup. By checking the levels of these substances, a full blood count test can reveal the following.

    • Abnormal red blood cells can be a sign of anemia, dehydration, or bleeding, for instance.[2]
    • Unusual white blood cells could be an indication of an infection, blood cancer, or an immune system disorder.[2]
    • An abnormal platelet count can reveal a potential bleeding disorder or a thrombotic disorder.
    • Abnormal hemoglobin levels may be a sign of anemia, sickle cell anemia, thalassemia, or other blood disorders.
    • High hematocrit levels could mean you are dehydrated, whereas a low hematocrit level could indicate anemia. Generally, hematocrit levels that are considered unusual could be a sign of a blood or bone marrow disease.

    So, with a complete blood count, you can detect diseases and conditions such as anemia, infections, blood cancers, and immune system disorders.[2]

    2. What Is a Basic Metabolic Lab Test?

    A metabolic test, or a basic metabolic panel test (BMP) is a group of tests that measure various chemicals in your blood, such as glucose, calcium, and electrolytes. Such a test can give you insights into how your organs are doing.

    When blood glucose is tested, this is often due to suspecting diabetes and to keep blood sugar levels under control. Abnormal calcium levels can indicate a wide range of health conditions, such as kidney problems, bone disease, thyroid disease, cancer, and malnutrition – for instance.

    Maintaining healthy electrolyte levels is key – sodium, potassium, and chloride (for example) are namely responsible for maintaining an optimal water balance in your body. Abnormal electrolyte levels can indicate a range of health problems, such as dehydration, kidney disease, liver disease, and high blood pressure. 

    3. What Does an Enzyme Blood Test Show?

    There are many different blood enzyme tests – each measuring the presence of a certain enzyme in your blood that helps control chemical reactions in your body. The most common blood enzyme tests are troponin and creatine kinase tests.

    Troponin levels rise when you have a heart attack; this is why doctors recommend carrying out troponin tests for chest pain or other heart attack symptoms. Creatine kinase tests measure a blood product called CK-MB, which indicates whether you have suffered a heart attack.

    4. What Blood Tests Detect Heart Problems?

    One of the most commonly carried out blood tests in the United States are tests that assess your risk of cardiovascular disease – for example coronary heart disease. Heart health tests include tests such as cholesterol tests, lipoprotein panel tests, and triglyceride tests.

    Doctors recommend a cholesterol test to evaluate the risk of cardiovascular disease for anyone over a certain age. These tests usually only require finger prick blood tests. 

    5. Blood Clotting Tests: What Blood Test Is Done for Clotting?

    Blood clotting tests are also called coagulation panels. These tests can reveal if you have a disorder that causes too much bleeding or too much clotting.

    You might be asked to take such a test if you suspect a bleeding disorder, if you have certain liver diseases, if you develop a blood clot within a blood vessel for no apparent reason, or if you take anticoagulant medications.[8]

    Why Are Blood Tests Important?

    Blood tests play an incontestable role in disease prevention, monitoring, and diagnosis. The information we obtain from blood tests is the foundation of how we can understand and treat illnesses as quickly and efficiently as possible.[4] 

    Some experts have stated that a hefty 40,000 to 80,000 deaths could be prevented annually in the United States if diagnostic errors were reduced.[1] Furthermore, lab tests in general – not just blood tests – save not only lives but also time and costs. While tests are not often free of charge, they offer a lot of important data for a comparatively small amount of money and are especially considered hugely beneficial when it comes to preventive health.

    Did you know that, according to the Centers of Disease Control and Prevention, that around 70 percent of medical decisions made today are dependent on laboratory test results, making such lab tests key for the US health system?[1]

    What Do Blood Tests Show – at a Glance

    What Are Blood Tests?

    Blood tests – that is, when a sample of your blood is extracted from your veins or arteries for lab analysis – are considered highly valuable in preventing or monitoring certain health conditions and diseases. 

    What Do Blood Tests Show?

    Blood tests are useful for a variety of reasons. They can help you diagnose a disease or condition, monitor health conditions such as diabetes closely, and check your organs and immune system are functioning healthily. 

    Why Are Blood Tests Important?

    Blood tests – like all clinical lab tests – are highly important for disease prevention and monitoring. The data obtained from blood tests can help medical practitioners decide on treatment, if it is necessary. 


    [1]     'Strengthening Clinical Laboratories,’ Centers of Disease Control and Prevention, available at, accessed on September 20, 2021.

    [2]     'Blood Tests,’ National Heart, Lung, and Blood Institute, available at, accessed on September 20, 2021.

    [3]      McNamara, C. 'Chapter 1 - Collection and Handling of Blood', Eds: Bain, B. J., Bates, I., Laffan, M. A., Dacie and Lewis Practical Haematology (Twelfth Edition), Elsevier, 2017, pp. 1–7,

    [4]      'Value of Lab Testing,' American Clinical Laboratory Association, available at, accessed on September 16, 2021.

    [5]      'What You Need to Know about Blood Testing,’ MedlinePlus, available at, accessed on September 16, 2021.

    [6]      'Examples: Blood tests,’ National Health Service, available at, accessed on September 16, 2021.

    [7]      'Capillary blood - Can it replace venous blood?' Human Diagnostics, available at, accessed on September 21, 2021.

    [8]      'Blood Clotting Tests',, available at, accessed on September 21, 2021.

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