Preparing for Lab Testing

By Kimberly Ferrell, MT (ASCP)

More than 70% of medical decisions are based upon laboratory test results; therefore it is critical to the well-being of the patients to obtain the most accurate information possible. Here are some tips to help you prepare.

Variables that could affect test results include the following:

• Exercise, age, sex, posture, obesity, stress, smoking and etc.
• Diet and lifestyle may affect results. It is generally recommended that the night before laboratory tests, patients avoid high-fat foods, alcohol and strenuous exercise.
• Patients should ask their doctors if certain medications should be stopped prior to lab testing as certain medications may interfere with results.

Important information to know about blood tests/other tests:

• Patients may need to fast prior to blood tests. For example, patients should not eat or drink anything except water for 9 to 12 hours prior to glucose and lipid profile tests.
• You may have to provide a urine specimen at the time you are having blood drawn. It is wise to be prepared and drink water before coming to the laboratory. 
• The amount of blood drawn for laboratory testing depends on the tests that are ordered. Usually the amount is very small (3-6 teaspoons).
• Some patients become anxious when they have blood drawn. Patients should tell the health care professional who is drawing the blood if they feel faint or sick. This is OK, and we would rather know that before the procedure so we can recline the patient to make him/her more comfortable. Slow deep breaths prior to the needle stick may also help to alleviate anxiety.
• A tight rubber band (tourniquet) is applied to the patient’s arm; this allows the vein to become more prominent. The phlebotomist presses areas on the arm with fingertip, looking for the best site to collect blood.
• Once the site is cleaned, the phlebotomist will draw the blood specimens.
• Patients may experience an uncomfortable pinch or pressure when the needle enters the site, however, the tubes rapidly fill with blood. Then the tourniquet is released from the arm, and the procedure is over very quickly.
• The phlebotomist makes sure all signs of bleeding have stopped and applies a bandage to the arm for a minimum of 15 minutes.
• Aspirin or other blood-thinning drugs can prolong bleeding. In such cases, patients may need continued applied pressure. A cold pack may be necessary to reduce swelling and bruising.
• After a patient has blood drawn, he/she should not carry or lift a purse or child (or other heavy object) with that arm for a minimum of 1 hour.

Collecting Specimens at Home:

• Patients must follow all instructions exactly for collection of specimens performed at home prior to being transported to the laboratory for testing.
• Special containers with a powder or liquid preservative may be provided for urine or stool collection. Patients should never empty or discard any powder or liquid from the container before beginning the collection of a specimen.
• Follow instructions provided by the laboratory for storing the specimen, until you can transport it. Take note that many specimens are required to be refrigerated until they are delivered to the laboratory.
• Remember to label the specimen with full patient’s name, Date of Birth, and time/date collected.
• Specimens should be delivered to the laboratory in the prescribed timeframe in order to assure accurate results.

Results:

• Depending on the laboratory work performed, test results may be available within a few hours to as long as several weeks. The completed results will be distributed to the ordering provider.
• Laboratory test results are often reported with a reference interval to assist the doctor or nurse practitioner in interpreting them. These reference intervals reflect the values in the majority of healthy individuals; however, a small number of healthy people (5%) may have results that are higher or lower than those in the reference range. Therefore, laboratory results should be interpreted by healthcare providers who can decide whether or not the results indicate a medical condition.
• Clinicians consider personal medical history, family history, and results from physical examination when interpreting an individual patient’s laboratory test results.
• If you desire to have a copy of your completed lab results, please ask for them at your appointment with the physician or contact the Health Information/Medical Records department at the facility that performed the laboratory testing. Laboratory staff members are not able to share any lab results with you over a telephone or in person because of strict privacy and protection laws.

It is always recommended that you call the laboratory with any questions or concerns prior to your visit for a blood collection or to drop-off a specimen that you are collecting at home.  Laboratory staff members are usually available on all shifts to help you.