Routine blood work can provide valuable information about your health. Learn more about different blood tests and what they can tell you. Blood testing is a way of measuring certain markers of health through a laboratory examination of a blood sample. Blood tests are very common in monitoring health, and they are often used to diagnose medical problems. These tests are generally
Blood testing is a way of measuring certain markers of health through a laboratory examination of a blood sample. Blood tests are very common in monitoring health, and they are often used to diagnose medical problems. These tests are generally simple, with almost no risk and minimal discomfort.
When you have a blood test, a sample of blood is sent to a laboratory and tested for different cells and substances. Often, the amount, size, and concentration of the cells and substances are reported with numerical values that are compared to standard or ideal values.
Examples of what can be tested in the blood include:
Blood tests can be used to detect signs of health risks, infection, the balance of fluids and minerals in the blood, an assessment of physical functions, and more.
Blood tests can measure certain components when the blood is taken to a lab and combined with specific chemicals that detect certain cells, proteins, hormones, enzymes. Blood test technology is always improving, and some blood tests can identify diseases that couldn’t be easily diagnosed years ago.
If you are having a blood test, you will have an order that specifies which tests you need. Some blood tests require preparation to ensure accurate results. Preparation may involve fasting (not eating or drinking) for a set amount of time prior to having the test or making certain medication adjustments.
During the test, the blood is placed into tubes that correspond to the type of tests you are getting. Some tubes contain material to maintain the components that are being tested. Then the sample is sent to the laboratory for testing.
A complete blood count is a very common blood test, and it measures the number of blood cells and the percentage of each type of blood cell.
A CBC includes:
A CBC also provides information about the size of each blood cell type. The results can help your healthcare provider determine if you may have anemia (a low number of healthy red blood cells), an infection, or indicators of other conditions.
Creatinine and BUN levels can reflect how well the kidneys are functioning. Sodium, potassium chloride, and calcium are electrolytes (charged minerals) that the body must keep in balance in the bloodstream. Bicarbonate reflects whether there is an imbalance in acid and base in the blood.
Severe abnormalities in these values can often indicate a medical emergency.
A lipid panel provides the count of triglycerides (a type of fat), low density lipoprotein (LDL), high density lipoprotein (HDL), and total cholesterol. Lipoproteins carry cholesterol, a waxy substance that is needed by the body but that can build up in blood vessels and cause problems.
These values reflect cardiovascular and stroke (a blockage of blood flow or bleeding in the brain) risk, with high levels of most lipid types usually associated with a high risk. However, low HDL (the so-called good cholesterol) levels are considered a risk factor for heart disease and stroke.
Blood tests can be used to detect specific hormones, proteins, enzymes, or markers in the blood that are indicators of various conditions. These types of tests may be used to diagnose and monitor a condition, as well as evaluate treatments for the condition.
People often wonder why a variety of tubes are used to collect blood. Which are drawn depend on the test, as some need specific additives in the tube. More than one of the same type of tube may be drawn because they are being sent to different sections of the laboratory or to different laboratories.
Results for tests sent to a laboratory that performs specialized tests may take longer to be reported than for standard blood tests.
Blood test frequency can vary. The types of blood tests you may need and the schedule of collection will depend on whether you have a chronic condition, new symptoms, or need medical screening tests.
Blood tests can also be done on a routine basis. Depending on your age and risk factors, you might need to have a lipid panel as part of standard health maintenance to determine whether your lipid levels could be putting you at risk of disease.
Another time for standard screening is during pregnancy, such as to monitor the pregnant person's blood glucose levels.
Sometimes blood tests are needed at certain scheduled intervals to monitor disease or to monitor a response to treatment. For example, if you are having treatment for systemic lupus erythematous (SLE, the most common type of lupus), you might need periodic blood tests to monitor your WBC count and ESR.
Blood tests may also be needed to help diagnose a suspected medical condition. For example, if you have unexplained weight gain, low energy, and have been feeling cold, you might need thyroid blood tests to determine whether you have thyroid disease.
Usually, blood test results are reported as numbers. The value that’s being measured—such as calcium or hemoglobin—is compared to the standard or ideal value.
The reported numbers from your blood test are not usually enough to make a diagnosis. You and your healthcare provider will need to discuss your overall health to put the numbers in perspective in terms of what they reflect about your health.
It can take hours, days, or longer for a blood test result to come back. If you are having an emergency blood test in a hospital, it might take less than an hour. It can take longer for results of specialized test results to come back.
Your blood type is one of the things that can be measured with a blood test. Blood type is designated by two types of markers—the ABO type and the Rh type. A blood typing test detects the presence or absence of these markers. The plus sign indicates Rh markers, while the minus sign indicates Rh-negative.
Blood types include:
All these blood types are perfectly healthy. The significance of these blood types is that when you need a blood transfusion the blood given to you must be carefully matched to your type to avoid causing an immune reaction, which can be deadly.
Before transfusion, the recipient should be typed and their blood tested against the donor blood units (called a crossmatching test).
In general, donor blood that has A, B, or Rh+ markers can only be given to people with those same markers. Anyone can receive O- donor blood. However, outside of emergencies, it's preferred that type-specific, crossmatched blood be given.
Blood tests are used to measure different components of blood, and the measurements are an indication of health. You might need some blood tests as part of routine health maintenance, to assess certain symptoms, or to monitor disease progression and treatment.
Getting a blood test is generally a simple procedure with very little risk. The process can be stressful, though, if you are afraid of needles or worried about test results.
Before a blood test, it can help to take a deep breath and stay calm and try to remember that the test isn’t harmful. Give yourself a chance to rest after your test for as long as you need to.
You can also ask how long it will take for results to come back. When you get your results back, you will be able to talk with your healthcare provider about what the results mean and what to consider as you decide on the next steps of treatment.