Understanding Your Laboratory Tests
"We're going to run some tests on you."
Did you ever wonder what your doctor means by that? When you provide blood, urine, or other body substances, these samples are sent to the medical laboratory, where the technical and professional staff process the sample, test it and report the results to your physician.
What Happens to Your Blood
Its all starts with the collection of a proper blood or other specimen. A doctor, nurse, technician, or phlebotomist will draw your blood. Several tubes of blood may need to be drawn for different types of tests.
Depending on what illness you might have, your doctor may want to obtain a urine sample, throat swab, or other sample. Follow the instructions carefully; the right sample leads to the right answers.
After the sample is collected, the container is labeled with your name and other information. If you are bringing a sample to the lab, make sure it has your name and number on it so that we do the proper tests and report them on the right patient.
ProcessingWhen the sample gets to the laboratory, it is logged into the hospital computer. In some cases, the liquid portion of blood is separated from the cells to prepare it for testing. It's then given to the laboratory staff who will perform the testing.
In the Chemistry section of the lab, blood and other body fluids are tested for chemicals, drugs and substances that indicate disease. Examples of Chemistry tests include cholesterol and other tests for risk of heart disease, glucose to monitor diabetes, cyclosporin to help physicians give the correct dose of this powerful drug, and thyroxin to monitor the thyroid gland.
The Hematology section of the lab analyzes the amount and function of blood cells and plasma. Examples of Hematology tests include the Complete Blood Count (CBC) that tells the doctor how many cells of each type are in your blood, and the prothrombin time (PT), to monitor patients on the drug Coumadin.
The Microbiology section of the lab tests patients for infections caused by bacteria, fungi or parasites. Many types of specimens -- including blood, urine, sputum, stool and others are tested. An example of a Microbiology test is a urine culture for urinary tract infections.
The Virology laboratory tests for viral infections. Depending on the virus suspected, the laboratory might look for the virus directly, or test your blood to see if your immune system has reacted to a virus. Examples of Virology tests include rapid tests for respiratory viruses such as influenza, molecular tests for noroviruses, and antibody tests for HIV.
- Immunology/Molecular Diagnostics
The Immunology/Molecular Diagnostics laboratory performs a wide variety of complex tests. Some tests are used by your doctor to determine whether your immune system is functioning properly. State-of-the-art analysis of DNA and RNA is used to test for a variety of diseases. and for the risk of developing certain diseases. Other specialized tests include the ANA, used to screen for autoimmune disease, and Factor V Leiden genotyping for patients with blood clots.
- Blood Bank (Transfusion Services)
The Blood Bank is a unique laboratory which not only tests patientsÕ blood types but also provides blood products to patients who need them. It does additional tests to assure the safety of transfused blood.
After the tests are done, results are reviewed and entered into the hospital computer system. For results that indicate the patient may be very ill, the laboratory calls the doctor with the results.Depending on how long it takes to carry out a particular test, the length of time between the drawing of the blood and when your provider gets the results can vary greatly, from as little as a few minutes to as much as several weeks. Most laboratory testing is done here, but some specialized testing is sent to other labs which are expert in particular tests.
Using the Results
Once the information is reported, your provider will interpret them based his or her knowledge of you. The test results may help to rule out or diagnose disease, or to do the best possible job of managing a known disease. You should ask your provider to explain your lab results to you, so you can participate in maintaining your health.