Types of Blood Tests

Some of the most common blood tests that doctors order are:

• Complete blood count (CBC)
• Blood chemistry tests
• Blood enzyme tests
• Blood tests to assess heart disease risk

Complete Blood Count

The CBC is one of the most common types of blood test. It's often done as part of a routine checkup.

A CBC measures many different parts of your blood (as described below). This test can help detect blood diseases and disorders. These include anemia, infection, clotting problems, blood cancers, and immune system disorders.

Red Blood Cells

Red blood cells carry oxygen from your lungs to the rest of your body. Abnormal red blood cell levels may be a sign of anemia, dehydration (too little fluid in the body), bleeding, or another disorder.

White Blood Cells

White blood cells are part of your immune system, which fights infections and disease. Abnormal white blood cell levels may be a sign of infection, blood cancer, or an immune system disorder.

A CBC measures the overall number of white blood cells in your blood. A differential count looks at the amounts of different types of white blood cells in your blood.

Platelets

Platelets (PLATE-lets) are blood cells that help your blood clot. They stick together to seal cuts or breaks and stop bleeding. Abnormal platelet levels may be a sign of a bleeding disorder (not enough clotting) or a thrombotic disorder (too much clotting).

Hemoglobin

Hemoglobin (HEE-muh-glow-bin) is an iron-rich protein in red blood cells that carries oxygen. Abnormal hemoglobin levels may be a sign of anemia, sickle cell anemia, thalassemia (thal-a-SE-me-ah), or other blood disorders.

If you have diabetes, excess glucose in your blood can attach to hemoglobin and raise the level of hemoglobin A1c.

Hematocrit

Hematocrit (hee-MAT-oh-crit) is a measure of how much space red blood cells take up in your blood. A high hematocrit level might mean you're dehydrated. A low hematocrit level might mean you have anemia. Abnormal hematocrit levels also may be a sign of a blood or bone marrow disorder.

Mean Corpuscular Volume

Mean corpuscular (kor-PUS-kyu-lar) volume (MCV) is a measure of the average size of your red blood cells. Abnormal MCV levels may be a sign of anemia or thalassemia.

Blood Chemistry Tests/Basic Metabolic Panel

The basic metabolic panel (BMP) is a group of tests that measure different chemicals in the blood. These tests usually are done on the fluid (plasma) part of blood. The tests can give doctors information about your muscles, including the heart; bones; and organs, such as the kidneys and liver.

The BMP includes blood glucose, calcium, electrolyte, and kidney tests. Some of these tests require you to fast (not eat any food) before the test, and others don't.

Blood Glucose

Glucose is a type of sugar that the body uses for energy. Abnormal glucose levels in your blood may be a sign of diabetes.

For some blood glucose tests, you have to fast before your blood is drawn. Other blood glucose tests are done after a meal or at any time with no preparation.

Calcium

Calcium is one of the most important minerals in the body. Abnormal calcium levels in the blood may be a sign of kidney problems, bone disease, thyroid disease, cancer, malnutrition, or another disorder.

Electrolytes

Electrolytes are minerals that help maintain fluid levels and acid-base balance in the body. They include sodium, potassium, bicarbonate, and chloride.

Abnormal electrolyte levels may be a sign of dehydration, kidney disease, liver disease, heart failure, high blood pressure, or other disorders.

Kidneys

Kidney tests measure levels of blood urea nitrogen (BUN) and creatinine. Both of these are waste products that the kidneys filter out of the body. Abnormal BUN and creatinine levels may be signs of a kidney disease or disorder.

Blood Enzyme Tests

Enzymes are chemicals that help control different reactions in your body. There are many blood enzyme tests. This section focuses on blood enzyme tests used to check for heart attack.

These include creatine kinase (CK) and troponin tests.

Creatine Kinase

When muscle or heart cells are injured, CK (a blood product) leaks out, and its levels in your blood rise. There are different types of CK. CK-MB is released when the heart muscle is damaged.

High CK levels can mean that you've had muscle damage in your body. High levels of CK-MB can mean that you've had a heart attack.

Troponin

This is a muscle protein that helps your muscles contract. Blood levels of troponin rise when you have a heart attack. For this reason, doctors often order troponin tests along with CK-MB tests when patients have chest pain or other heart attack signs and symptoms.

Blood Tests To Assess Heart Disease Risk

Abnormal levels of certain chemicals in the blood may mean that you’re at higher risk for heart disease. Your doctor may want to test the levels of these chemicals to assess your risk and to suggest ways to reduce it.

Lipoprotein Panel

This test can help show how high your risk is for coronary heart disease. A lipoprotein panel looks at substances in your blood that carry cholesterol.

The test gives information about your:

• Total cholesterol.
• LDL ("bad") cholesterol. This is the main source of cholesterol buildup and blockages in the arteries.
• HDL ("good") cholesterol. This type of cholesterol helps decrease blockages in the arteries.
• Triglycerides. These are another form of fat in your blood.

A lipoprotein panel measures the levels of HDL and LDL cholesterol and triglycerides in your blood. Abnormal cholesterol and triglyceride levels may be signs of increased risk for coronary heart disease.

Most people will need to fast for 9 to 12 hours before a lipoprotein panel.

High-Sensitivity C-Reactive Protein

This is a fairly new test for heart disease risk. It looks at blood levels of C-reactive protein (CRP). High CRP blood levels can be a sign of inflammation.

Doctors use standard CRP tests to check for inflammation and autoimmune diseases. Your doctor may order an hs-CRP test, along with other tests, to see whether you’re at increased risk for heart disease.

However, CRP tests aren’t routinely done, because it’s still unclear how useful they are for showing heart disease risk.

Homocysteine

High levels of this chemical in the blood can mean that you’re at higher risk for heart attack or stroke. This isn’t a routine test for heart disease risk. But some doctors may use it, a long with other tests, if they think you’re at increased risk.