Why do you need a laboratory test?
Your physician will order laboratory tests in order to obtain information which cannot be learned through your history and physical examination. This information will assist in the determination of your overall health, in the diagnosis of a disease and in the establishment of appropriate treatment. There are many reasons for laboratory tests, all of which will provide valuable information to your doctor.
What are normal values or reference ranges?
Reference ranges used to be called normal ranges. They reflect the results expected for 95% of your neighbors. These cannot be national in scope or even by state but must be developed by the clinical laboratory scientists in your local laboratory. This is due to the fact that they are affected by the type of instrument and reagents used, the principle or method for the test that is being performed and the type of population being served. For example, children may not have the same ranges as adults and men may have different values than women. You can find out the reference range for your laboratory test by reading the column of numbers to the right of your results on the printed copy of your results.
If you did not receive a printed copy, then contact your physician's office or the clinical laboratory scientists who performed the testing for the exact reference ranges for you and your laboratory test. If you do have the results and would like us to comment on them, please send us your values and the reference ranges.
What can be tested?
Your body is made up of many different types of cells and fluids. Almost all of these cells and fluids may be tested, though the most common specimens are blood and urine. Materials such as sweat, spinal fluid, joint fluid, sputum, hair, feces, bone marrow, tissues and body scrapings are also analyzed.
Who will perform your tests?
The clinical laboratory staff is a team of skilled professionals with education in a variety of scientific areas. The majority of laboratory testing is performed by Clinical Laboratory Scientists (Medical Technologists) with four years of education and Clinical (Medical) Laboratory Technicians with two years of education. Other individuals involved in clinical laboratory practice include physicians (pathologists), other scientists (chemists, microbiologists), laboratory assistants and phlebotomists.
What do you need to know before the test?
Depending upon the specific tests your doctor has ordered, you may be told not to eat for several hours before coming to the laboratory or to eat certain foods. Other tests may require you to increase or decrease the amount you drink for 10 or 12 hours ahead of time. You may be asked not to smoke before the tests. When you are told by your doctor that he is ordering tests, always ask for special instructions or consult the Medical Technologist at the laboratory to learn of any special preparations which are needed.
How are specimens collected?
For blood tests, two methods are used to obtain samples. Your finger may be pricked for a small amount in a tube or a smear on a glass slide. More commonly, a vein on the inner side of your arm will be selected for a venipuncture. The laboratory professional will instruct you on the proper collection of urine samples, feces, sputum, semen or other materials which you can collect even at home.
When will the doctor have your test results?
Most laboratory procedures can be completed in a few hours. This means that the doctor will have your results on the same day as the test if you are a patient in the hospital or within 2-3 days if you are an outpatient. Some procedures, however, require several days to complete, which means that sometimes the physician will not have the results for a week.
What test might you expect?
There are thousands of possible laboratory tests, with around 500 performed in most institutions. The most common (the most frequently requested tests) are listed here for your information.
Have a question about a laboratory test?
If you have any questions about doing a test, or interpreting the results, contact us by completing
our online lab testing information request form, and a certified clinical laboratory scientist will gladly help you!