Will my results vary from another lab?
The type of tests performed at Everlywell’s clinical laboratories may, in many cases, be performed at other laboratories. For example, cholesterol testing is offered by Everlywell as part of the Cholesterol and Lipids Panel and is widely offered by hospitals’ laboratories. You may happen to have results from both. What can you expect if you receive results from Everlywell and compare them to test results you may have received at another laboratory?
In general, results between laboratories, when using the same test method and sample type, will be very similar, but not necessarily exactly the same. This is expected because each laboratory establishes its own reference ranges. Reference ranges are the span of measured values in which patient samples are considered normal and/or abnormal. The College of American Pathologists (CAP) requires inter-laboratory testing and monitors the results to ensure that laboratories are not operating out of acceptable range.
Often the sample type that is tested differs. The method of testing may also differ. If the sample type and/or the test method differ from your Everlywell test, you may notice that the result values are different.
Everlywell uses minimally invasive methods to collect samples. We use the following sample types in our testing:
- Saliva, deposited orally in a small collection tube
- Dried Blood Spot, collected by pricking a fingertip with a lancet and dropping several samples onto designated areas on absorbent paper
- Urine, collected by dipping absorbent paper into urine stream or urine collected in a small, clean container
These sample types are convenient for the customer to collect. They are very stable and can withstand extreme shipping and storage conditions without interfering with the test results.
Many, if not most, testing methods and laboratories rely on a venous blood draw for samples. This requires customers to visit a blood draw facility and trained phlebotomy staff to draw a blood sample. Venous blood draws may yield blood, serum, or plasma. Of these, serum is most frequently required for testing. Serum and other sample types may not yield the same values on the same test. One common reason is that serum contains protein that can bind to many substances, and this may interfere with measurements.
There are many tests used to measure the same analytes. An analyte is the material being tested. For example, cholesterol is the analyte in a cholesterol test from a serum sample. Cholesterol in serum may be measured by immunoassay or by spectrophotometry, two different test methods. The two results may not be directly comparable, because they come from two different tests. However, the reference ranges for the two tests should yield the same diagnosis from an individual. Again, CAP ensures that each laboratory test is operating as intended.
If your test results differ significantly, consider first whether the sample type and test methods are really the same. If your results (for example, normal vs. high risk) are the same for the two tests, then the reference ranges are likely different because the test methods are not directly comparable.