There are a few reasons why a test may be repeated. For example:
1. A test may be repeated when a result indicates that you may have a disease or condition. Repeat test results that match the initial results confirm a diagnosis. For example, if the results from a fasting glucose test are high, the test is repeated. If it is high again, then a diagnosis of diabetes is confirmed.
2. If a result does not seem to fit with your overall health level, such as your signs and symptoms and physical exam results, your health care provider may reorder the test. Here are a few examples of why the results can be unexpected:
A. It is possible that the substance measured in the test happened to be high or low because of something you ate, recent physical exercise, or another circumstantial situation.
B. Though uncommon, errors due to improper processing or transportation of the sample (such as refrigeration issues, exposure to heat, etc.) can affect the accuracy of results.
3. A test may be repeated if there was not enough sample collected to perform the full panel of tests, or if the sample was not collected properly. For instance, if you do not collect all of your urine for a 24-hour urine test, it may need to be repeated.