What affects the outcome of test results

One of the most important things in determining the accuracy and reliability of your laboratory test is you, the individual. It is therefore essential that you do the following to ensure that the results are useful:

  • Follow any instructions you are given by your doctors to prepare for the specific test you are having performed.
  • Alert the person collecting your sample if you have not followed the instructions and in what way.
  • Inform your doctor of any medications (including herbal remedies, vitamins and supplements) you might be taking or aby particular foods you have eaten within the day prior to the test.

Many tests require no special preparation but for those that do, keep to the instructions given to you by your doctor.

Examples of some frequent laboratory tests that require advance preparation include:

Glucose tolerance

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Blood glucose tests

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Faecal occult blood test

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Serum lipids (triglycerides, cholesterol, etc.)

GLUCOSE TOLERANCE

  • The patient should first arrange with the laboratory for appointment.
  • Prior to the test, the patient must have fasted for at least ten (10) hours, but not longer than sixteen (16) hours.
  • It is advisable that the patient drinks a lot of water, to be able to pass enough urine.
  • Patient must be healthy e.g. No flu, pneumonia, abscesses.
  • The patient should not be on any medication, unless prescribed by doctor.
  • The patient is not allowed to smoke after getting up in the morning, until after the procedure.
  • Should the patient vomit after drinking the glucose, the results will be useless, and the testing must be rescheduled.

FAECAL OCCULT BLOOD

Three days prior to collection, avoid:

  • Red Meat, Beetroot, Carrots, Cucumbers, Mushrooms, Grapefruit, Cauliflower, Broccoli
  • Vitamin C- enriched foods or beverages, Vitamin C supplements (Ascorbic) and multivitamin preparations
  • Alcohol
  • Aspirin /Disprin, Anti-inflammatory drugs

INSTRUCTIONS FOR COLLECTION OF URINE FOR 5-HYDROXYINDOLEACETIC ACID (5HIAA)

Three days prior to collection of urine specimen for 5HIAA, the following instruction must be adhered to:

  • Avoid the following food:

Bananas, Avocados, Eggplant, Pineapple, Tomatoes, Prunes, Nuts, Chocolate and Caffeine products

  • Avoid the following drugs:

Paracetamol, Caffeine, Valium, Spasmed, Naprosyn, Aspirin, Largactil, Ethanol, Tofranil, Homogentisic Acid, Levodopa, Nicotine

24-HOUR TIMED URINE COLLECTION

IMPORTANT INFORMATION BEFORE START OF COLLECTION

  • DO NOT pass urine directly into the bottle (it contains a preservative that may splash, burn or irritate your skin).
  • DO NOT remove the preservative from the bottle.
  • Keep the bottle upright so that it does not spill.
  • Urinate in a clean dry container and transfer the urine into the bottle carefully.
  • KEEP OUT OF REACH OF CHILDREN. IF THE LIQUID IN THE BOTTLE IS SPLASHED OR SPILLED, WASH SPILL IMMEDIATELY WITH WATER.

SPECIMEN COLLECTION

  • Empty the bladder when you first get up in the morning. DISCARD this urine. RECORD the time on the bottle provided by the laboratory.
  • From that time, save all urine up to and including the first morning specimen at the end of the 24 hours (or other designated time period).
  • During collection and until the specimen is brought to the laboratory, the urine should be refrigerated or kept on ice (in a bucket).
  • Record on the urine container, the time the last part of the specimen was collected.
  • Be careful not to deposit toilet tissue in the specimen or allow it to become contaminated with fecal material.
  • If the container has a preservative, (orange sticker or otherwise indicated), handle the container with caution. Specific instructions are available on the label, and/or by calling the appropriate laboratory listed above.
  • Bring the container with urine to the laboratory as soon as possible.
  • As a part of some tests, a blood sample must also be collected. Check with the individual laboratory to verify that a sample is not needed.

There are many factors that can affect laboratory test results. Things that may interfere with the accuracy of your laboratory test include:

  • Not following the instructions for how to prepare for the test. Some tests, such as a cholesterol and triglyceridesanalysis, might require you to stop eating for at least 12 hours before the test.
  • Some medicines or herbal treatments. For example, some medicines can raise or lowerblood sugar levels and could interfere with glucose (blood sugar) tests. Some birth control pills or steroids can raise blood sugar, while some medicines to treat high blood pressure and depression can lower it.
  • Drinking caffeinated beverages (energy drinks) or alcohol.
  • Vigorous exercise.
  • Pregnancy.

It is very important to follow your doctor’s instructions to make sure that your test results are as accurate as possible.