Blood Test
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Blood Test
A blood test is one of the most common tests healthcare providers use to monitor your overall health or help diagnose medical conditions. You may have a blood test as part of a routine physical examination or because you have certain symptoms.
Overview
Blood tests are common medical tests. You may have a blood test as part of a routine physical examination or because you have certain symptoms.
There are many different blood tests. Some tests focus on your blood cells and platelets. Some evaluate substances in your blood such as electrolytes, proteins and hormones. Others measure certain minerals in your blood.
Regardless of why you’re having a blood test, it’s important to remember that blood tests help healthcare providers diagnose health issues. But blood test results aren’t diagnoses. An abnormal blood test result may not mean you have a serious medical condition.
When would I need to have a blood test?
Your blood plays a big role in your overall health and contains a lot of information about what may be going on in your body. That’s one reason why blood tests are a common medical test. A healthcare provider may do a blood test because:
- It’s time for your regular physical. During a checkup, your provider may order blood tests to check on your overall health. They may order a blood test that evaluates many parts of your blood, such as a complete blood count (CBC), basic metabolic panel (BMP) or a comprehensive metabolic panel.
- Your provider recommends screening tests. Screening tests are done before you have any symptoms. They may recommend screening tests if you’re at risk of developing certain conditions, such as cancer. For example, if you’re at risk for developing coronary artery disease, your healthcare provider may order several blood tests to evaluate that risk.
- You don’t feel well. If you have specific symptoms, your provider may order blood tests to determine what’s causing them. For example, if you have symptoms that may be signs you’re pregnant, your provider will do a pregnancy test. The blood test looks for a specific hormone your body only ever makes when you’re pregnant.
- You have a medical condition that happens when certain genes change (mutate). Depending on your situation, your blood cells and platelets may show information about the specific changes. Understanding which genes changed may help your provider plan your treatment.
- You’re receiving treatment for a medical condition. Your provider may use regular blood tests to see if treatment is working.
- You may have inherited certain genetic mutations that cause medical conditions. Your provider may take blood samples for genetic analysis so you know if you’re at risk of developing a specific condition.
What do blood tests show?
In a broad sense, a blood test shows changes in your body. Blood test results don’t show a complete picture. Instead, they’re a kind of snapshot. After seeing that snapshot, your provider may do other blood tests to get a closer view. Here’s a glimpse of what your healthcare provider may see with blood tests:
- The tests show if your blood is working as it should. For example, your red blood cells carry oxygen throughout your body. A blood test may show you have low red blood cell levels (anemia). If healthcare providers look at your cells under a microscope, they may see your red blood cells are larger than normal or shaped differently than normal red blood cells. These differences may be signs of blood disorders or blood cancers.
- They show if you have normal levels of enzymes and electrolytes. Enzymes are proteins that help speed up the chemical reactions that build up and break down substances in your body. Electrolytes do several things, such as helping your body regulate chemical reactions and maintaining the balance between fluids inside and outside your cells.
What are the most common blood tests?
There are many different blood tests. Some tests — such as complete blood count tests, basic metabolic panels, complete metabolic panels and electrolyte panels — check on several different elements in your blood at the same time. Other blood tests look for very specific elements in your blood.
What does a complete blood count (CBC) test show?
This is the most common blood test that includes several specialized tests. CBC tests:
- Count and measure your red blood cells, white blood cells and your platelets. A CBC test includes a hematocrit test that measures the percentage of red blood cells in your blood.
- Measure your hemoglobin levels.
- Measure variations in your red blood cells’ size and volume with an RDW blood test (RDW stands for “red blood cell distribution width”).
- Measure the average size of your red blood cells with a mean corpuscular volume (MCV) test.
What does a basic metabolic panel show?
A basic metabolic panel (BMP) measures several substances in your blood. Healthcare providers use BMPs to evaluate your overall health and screen for or monitor health issues. A BMP may include a:
- Blood glucose test: Screens for diabetes.
- Calcium blood test: Checks to make sure you have appropriate levels of calcium, a mineral that helps with many of your body’s functions.
- Blood urea nitrogen (BUN) test: Measures the amount of urea, a waste product that passes through your kidneys. BUN tests show the amount of urea nitrogen in your kidneys.
- Creatine kinase (CK) test: Screens for a waste product your muscles produce. High CK levels may be a sign of injured or damaged muscles.
- Sodium levels.
- CO2 blood test: Measures the amount of bicarbonate in your blood. This test detects carbon dioxide.
- Serum potassium test: Measures potassium levels. Potassium supports your heart, nerve and muscle function and your metabolism.
- Chloride blood test: Checks on chloride, an electrolyte that helps keep your body fluids and acids balanced.
- Globulin blood test: Measures how much of this protein your liver produces.
What does a comprehensive metabolic panel show?
Comprehensive metabolic panels (CMP) include all the blood tests done as part of a basic metabolic panel. Additional blood tests include:
- Albumin blood test: Albumin is a protein in your blood plasma. This test checks on kidney and liver function.
- Alanine transaminase (ALT): Healthcare providers use this test to assess liver health.
- Alkaline phosphatase (ALP): High levels of this enzyme may indicate liver disease or certain bone disorders.
- Ammonia levels: Blood tests will show the amount of ammonia in your blood. High ammonia levels may be a sign of liver and kidney damage.
- Bilirubin blood test: Bilirubin is a substance in your liver’s bile. Too much bile in your blood may be a sign of liver issues.
- Aspartate transferase: Sometimes called AST, this test measures the amount of the enzyme aspartate transferase in your blood. Providers use this test to assess liver health.