Blood Test

Jai Ganesh · 2025-01-25 17:58:49

Blood Test

Gist

The complete blood count (CBC) is one of the most common blood tests. It is often done as part of a routine checkup. This test measures many different parts of your blood, including red blood cells, white blood cells, and platelets.

Complete blood count (CBC)

The complete blood count (CBC) is one of the most common blood tests. It is often done as part of a routine checkup. This test measures many different parts of your blood, including red blood cells, white blood cells, and platelets.

* Red blood cell levels that are higher or lower than normal could be a sign of dehydration, anemia, or bleeding. Red blood cells carry oxygen from your lungs to the rest of your body.
* White blood cell levels that are higher or lower than normal could be a sign of infection, blood cancer, or an immune system disorder. White blood cells are part of your immune system, which fights infections and diseases.
* Platelet levels that are higher or lower than normal may be a sign of a clotting disorder or a bleeding disorder. Platelets are blood cell fragments that help your blood clot. They stick together to seal cuts or breaks on blood vessel walls and stop bleeding.
* Hemoglobin levels that are lower than normal may be a sign of anemia, sickle cell disease, or thalassemia. Hemoglobin is an iron-rich protein in red blood cells that carries oxygen.
* Hematocrit levels that are too high might mean you’re dehydrated. Low hematocrit levels may be a sign of anemia. Hematocrit is a measure of how much space red blood cells take up in your blood.
* Mean corpuscular volume (MCV) levels that are lower than normal may be a sign of anemia or thalassemia. MCV is a measure of the average size of your red blood cells.

Summary

A blood test is a lab analysis of things that may be found in your blood. You may have blood tests to keep track of how well you are managing a condition, such as diabetes or high cholesterol. You may also have them for routine checkups or when you are ill.

Blood tests are very common. They are ordered by healthcare providers to:

* Find out how well organs, such as your kidneys, liver, heart, or thyroid are working

* Help diagnose diseases, such as cancer, diabetes, heart disease, and HIV/AIDS

* Find out if your medicine is working to make you better

* Diagnose bleeding or clotting disorders

* Find out if your immune system is having problems fighting infections

* Diagnose anemia, such as iron-deficiency anemia, pernicious anemia, aplastic anemia, or hemolytic anemia

* Find variations in hemoglobin, such as hemoglobin S, C, or E, which are common in people of African, Mediterranean, or Southeast Asian background

* Monitor chronic health conditions and diseases

* Find health problems in their early stages

You have the right to know why a blood test has been ordered and how much it will cost. Ask your healthcare provider if you are not sure why they want you to have the test.

Types of blood tests

These are common blood tests:

* Complete blood count, also called a CBC

* Blood chemistry tests

* Blood enzyme tests

* Blood tests for heart disease risk

Blood tests can give your healthcare provider a lot of information. They can see if certain elements in your blood are in a normal range. But in many cases, blood tests are only part of the information your healthcare provider needs to make a diagnosis of a health condition. You might need to have some other types of tests as well.

Preparing for a blood test

For most kinds of blood tests, you don't need to prepare. These tests are to see what your blood is like under normal conditions.

For some blood tests, you will have to fast for a certain amount of time before the blood test. The fasting time may vary depending on the test. These tests are often scheduled for early in the morning.

Your healthcare provider will let you know if you need to fast before a blood test.

The procedure

To test your blood, a technician called a phlebotomist will use a needle to take a sample of blood. Tell the technician if the sight of needles makes you nervous. They can help you feel more at ease. You can also look away during the procedure, and bring a family member or friend to help distract you.

In most cases, the sample is taken from a vein in your arm. You will be seated or lying down. You may be asked to make a fist. The technician will tie a rubber band around your arm. Once they see a vein, the technician will clean the area and then insert the needle. You might feel a small prick or stinging sensation. Once the technician has drawn enough blood, they will take the needle out and put an adhesive bandage over the site. You may be asked to press firmly on the site to stop any bleeding.

After the procedure

Your blood sample will be sent to a lab. Trained technicians then look for the information the healthcare provider has ordered. This may take a day or up to a week or more. Ask your healthcare provider’s office how you should expect to find out about the results. In many cases, the results will be posted online in the provider's web portal.

Details

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:

What are blood tests?

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.

What does an electrolyte panel show?

Electrolytes are minerals in your blood. Imbalance with electrolytes may be a sign of issues with your heart, kidneys or your lungs. An electrolyte panel includes all electrolyte tests in BMPs and CMPs. Additional electrolyte levels tested include magnesium and anion gap. Magnesium supports your brain, heart and muscles. Anion gap tests check the acid-base balance in your blood.

What does an electrolyte panel show?

Electrolytes are minerals in your blood. Imbalance with electrolytes may be a sign of issues with your heart, kidneys or your lungs. An electrolyte panel includes all electrolyte tests in BMPs and CMPs. Additional electrolyte levels tested include magnesium and anion gap. Magnesium supports your brain, heart and muscles. Anion gap tests check the acid-base balance in your blood.

What blood tests do healthcare providers use to help diagnose specific conditions?

While the various blood and electrolyte panel tests provide a lot of information, there are disease-specific blood tests that help providers diagnose and treat specific conditions.

Allergies

An allergy blood test checks your blood for increased levels of immunoglobulin E (IgE) antibodies. The test can help detect allergies to foods, pets, pollen or other irritating substances.

Autoimmune diseases

Autoimmune diseases happen when your immune system accidentally attacks your body instead of protecting it from intruders like viruses, parasites and cancer. Your provider may order the following blood tests:

* Antinuclear antibody test: Antinuclear antibodies (ANA) are antibodies that mistakenly attack your immune system. Large amounts of ANA in your blood may be a sign of certain autoimmune disorders.
CE complement blood test: Providers may use this test to diagnose and monitor autoimmune disorders like rheumatoid arthritis or lupus.
* C-reactive protein (CRP) test: Your liver makes and releases this protein. High C-reactive protein levels may be a sign of inflammatory conditions, including some autoimmune diseases.
* Erythrocyte sedimentation rate (ESR): ESR tests help detect inflammation.
* Peripheral blood smear (PBS): This is a technique healthcare providers use to examine your red and white blood cells and your platelets under a microscope.

Cancer/Noncancerous blood disorders

Healthcare providers may use several different tests to diagnose and treat cancer, blood cancer and noncancerous blood disorders.

Cancer blood tests

Blood tests for cancer fall into four basic categories — complete blood count, tumor markers, blood protein testing and circulating tumor tests. CBC, tumor markers and circulating tumor tests may help detect some solid tumors. Blood in your poop (stool) or pee (urine) may also be a sign of cancer.

Complete blood count (CBC)

A CBC measures red and white blood cell and platelet levels. Abnormally high or low blood cell or platelet levels may be a sign of some types of cancer.

Tumor markers

Tumor markers are substances made by cancerous cells or your body’s normal cells in response to cancer. Tumor marker blood tests include:

* Alpha-fetoprotein (AFP) for liver cancer.
* CA-125 blood test for ovarian cancer.
* Calcitonin for thyroid cancer.
* Cancer antigens 15-3 and 27-29 for breast cancer.
* Carcinoembryonic antigen (CEA) for a range of cancers.
* Human chorionic gonadotropin (HCG) for testicular cancer and ovarian cancer.
* Prostate-specific antigen (PSA) for prostate cancer.

Circulating tumor test

The circulating tumor test is a relatively new blood test for cancer. This test looks for cancerous cells that have broken away from a tumor and into your bloodstream. Currently, it can help monitor certain types of cancer, such as breast, prostate and colorectal cancers. Scientists are still developing the technology.

Other blood tests

Healthcare providers may use the same tests to diagnose blood cancer or noncancerous blood disorders:

* D-dimer test: Healthcare providers use this test to diagnose blood clotting disorders.
* Fibrinogen test: Fibrinogen is a protein that helps with blood clotting.
* Kappa or Lambda free light chain: This test detects high protein levels in your blood plasma. Healthcare providers may use this test to diagnose amyloidosis, which is a noncancerous blood disorder, or to diagnose blood cancers such as multiple myeloma.
* Prothrombin time test (PTT): Healthcare providers may use this test to diagnose blood clotting disorders.
* Reticulocyte count: This test checks to see if your bone marrow is producing enough healthy red blood cells.

Some blood tests don’t involve providing blood samples, such as:

* Fecal occult blood test (FOBT): FOBTs screen for colorectal cancer by looking for blood in your poop (stool).
* Urinalysis: Healthcare providers may use this test to detect blood cells in your pee (urine).

Endocrine system disorders

Your endocrine system is made of organs called glands. Glands produce hormones. Healthcare providers may use blood tests to diagnosis conditions affecting parts of your endocrine system. Common blood tests include:

* Blood glucose test: This test measures your blood glucose level. It’s used to diagnose diabetes. Another diabetes blood test is A1C, which measures blood glucose over time.
* Thyroid stimulating hormone test (TSH): There are several blood tests to diagnose thyroid disorders.
* Pancreas blood tests: Your pancreas produces enzymes. These tests check lipase and amylase levels.

Heart disease

Some blood tests evaluate your risk of developing heart disease:

* Cardiac blood tests: Your healthcare provider may order these tests if you’re at risk of having a heart attack or developing heart disease.
* Arterial blood gas (ABG) test: This test measures oxygen levels and carbon dioxide levels, among other things. Healthcare providers may do this test to diagnose acute heart failure and cardiac arrest.

Specialized blood tests

Your healthcare provider may recommend specialized blood tests, including:

* 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.
* Blood alcohol content (BAC): This test measures the amount of alcohol in your system.
* Ferritin: You may have a ferritin test if your CBC tests show you don’t have enough iron.

When should I have a blood test?

That depends on your situation and your overall health. Most healthcare providers recommend annual physical examinations that may include a complete blood count test. In general, providers recommend tests based on what they know about you. For example, they may recommend regular blood glucose tests if you have overweight (a Body Mass Index or BMI over 25) or obesity (a BMI greater than 30).

Additional Information

A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a cholesterol test, are often grouped together into one test panel called a blood panel or blood work. Blood tests are often used in health care to determine physiological and biochemical states, such as disease, mineral content, pharmaceutical drug effectiveness, and organ function. Typical clinical blood panels include a basic metabolic panel or a complete blood count. Blood tests are also used in drug tests to detect drug abuse.

Extraction

A venipuncture is useful as it is a minimally invasive way to obtain cells and extracellular fluid (plasma) from the body for analysis. Blood flows throughout the body, acting as a medium that provides oxygen and nutrients to tissues and carries waste products back to the excretory systems for disposal. Consequently, the state of the bloodstream affects or is affected by, many medical conditions. For these reasons, blood tests are the most commonly performed medical tests.

If only a few drops of blood are needed, a fingerstick is performed instead of a venipuncture.

Indwelling arterial, central venous and peripheral venous lines can also be used to draw blood.

Phlebotomists, laboratory practitioners and nurses are those in charge of extracting blood from a patient. However, in special circumstances, and/or emergency situations, paramedics and physicians extract the blood. Also, respiratory therapists are trained to extract arterial blood to examine arterial blood gases.

Math Is Fun Forum

#1 2025-01-25 17:58:49

Blood Test

Board footer