Why can reference ranges vary?
Normal lab values, also referred to as expected values, are ranges that are considered acceptable for the average adult.
Laboratories establish their own reference ranges based off many factors including internal controls and general population data. Although reference ranges are likely similar, there can be slight differences if testing was performed at different laboratories. When comparing test results, it's also important to note the units of measure and sample type because that can also influence the reference range.
In general, it's often the pattern of results over time or where you fall within the range itself that indicates if someone is healthy, or if a follow-up is needed with their healthcare provider.