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There are hundreds of different blood tests available to help healthcare professionals understand your health.
These tests are often the starting point and more tests may be necessary if your results from these common tests are abnormal.
Red blood cell count (RBC count)
The job of the red blood cell is to carry oxygen from your lungs to the rest of your body. When your RBC count is low, it could mean a number of things including anemia and poor diet. When it is high, it could mean you are dehydrated or have a medical condition such as heart disease.
White blood cell count (WBC count)
White blood cells help your body fight infection. If your count is high, it may mean you are fighting an infection. If your count is lower than normal, it may mean your immune system is affected or weakened by a medical condition.
Complete blood count (CBC)
This test looks at both your red and white blood cells. It also measures your platelets, which are blood cell fragments that help your blood clot. This is important when you get cut so you stop bleeding. The CBC also looks at your hemoglobin, which is the iron-rich protein in red blood cells that carries oxygen and hematocrit, which is a measure of how much space your red blood cells take up in your blood volume. All of this information tells your health care provider about your overall health. The CBC test is often done as part of a routine medical exam or physical.
Blood chemistry tests
Your blood says a lot about you. Many substances, such as glucose (a type of sugar in your blood) and calcium, are carried in your blood. These substances can affect your health if the levels are too high or too low. For example, if you have too much glucose in your blood you may have diabetes. Another example would be when blood tests show you don’t have enough B12, you could have a deficiency of that vitamin. Here are some other common blood chemistry tests. You also may hear this group of tests called a metabolic panel.
Part of your liver’s job is to break down old red blood cells. A product of red blood cell breakdown is called bilirubin. If your bilirubin levels are too high, it could mean you have a medical condition affecting your liver, gallbladder or bile duct.
If you are having surgery, you likely will have a blood test to find out what your blood type is in case you should need extra blood (blood transfusion) during or after your surgery. You will also have a blood type test if you are pregnant. Some people simply want to know what their blood type is and choose to have a blood test so they can find out.
Blood Urea Nitrogen (BUN)
Urea nitrogen is what forms when protein breaks down. If this test is abnormal, it could mean many things, from a heart condition to liver problems to a low-protein diet. However, it is used most often to check how well your kidneys are working. If this test is abnormal, your healthcare provider will likely want you to have more tests.
Calcium is important for healthy teeth and bones. Certain health conditions can cause this test to be abnormal. For example, if you have a gastrointestinal condition, your body may not absorb enough calcium from your food during digestion. This would make your calcium level too low. Your calcium level also could be too high. This could be from taking a calcium supplement that you don’t need or from a medical condition.
Cholesterol & Triglycerides
Cholesterol is carried through your blood. There is LDL cholesterol or “bad” cholesterol that is sticky. It can build up and block your arteries. There also is HDL cholesterol or “good” cholesterol, which helps to stop the bad cholesterol from sticking to your artery walls. Triglycerides are the most common form of fat in the body. You want your bad cholesterol and triglyceride levels to be low to prevent heart disease.
This test is used to check your kidney function. Many medical conditions can cause this test to be abnormal. The most common reason is diabetes.
Some diseases can be detected by a blood test. Human immunodeficiency virus (HIV) and Hepatitis C are two examples.
Drugs and poisons
Alcohol and illegal drug use can be found through blood tests. Prescription drugs can also be detected and help your doctor see how your treatment is working for you.
Hormones are substances in the blood that tell your body what to do. Hormones affect your growth and development, metabolism, sexual function, reproduction and your mood. A common hormone test checks the chorionic gonadotropin (HCG) hormone found in the blood when a woman is pregnant.
This test is often done to see how well your liver, stomach and kidneys are functioning. If you have an abnormal result, your healthcare provider will likely order more tests.
Your body forms uric acid as it breaks down purines, a substance found in some foods. This test is commonly done if your healthcare provider suspects you have gout, a condition that causes pain and swelling in your feet. This test can also be done to check the health of your kidneys. Aside from eating a diet that is high in purines, abnormal uric acid levels in your blood can be caused by many medical conditions.
Viruses and bacteria
There are many different types of bacterial and viral infections that can be detected with blood tests. These infections can begin in any part of your body and spread to your blood. You may hear some of these tests called blood cultures. This is because the samples are sent to a lab and watched to see if the bacteria or virus grows. It can take several days to get the results of these tests.
Blood clotting tests
These tests are often done before surgery or if you are on a medication that may affect how your blood clots. You may hear the term “coagulation panel” when your healthcare provider orders these tests to make sure your blood clots properly (not too fast or too slow). You also may need this test if your healthcare provider thinks you may have a blood-clotting disorder.
Blood enzyme tests
Just like blood chemistry tests, there are many kinds of blood enzyme tests. One of the most common tests looks for the enzyme troponin that is released during a heart attack.