Healthcare providers sometimes see discrepancies in the reference range that appears on their patient’s lab report and the reference range listed as “standard” in their Optimal DX report. How reference ranges are used by a big lab network is like this:
Most large commercial labs, including LabCorp, do not use a single reference range for a particular biomarker. Each facility verifies its own reference interval, and multiple valid reference ranges can exist within the same lab company. The standard range provided in ODX is based on the lab’s referenced standard range as defined on the lab’s website-not on any one facility’s report; therefore, the two may not align perfectly.
We compared three separate LabCorp lab reports completed over the course of a single week. We found that one facility in Houston reported a reference interval for BUN ranging from 8 to 27 mg/dL. A second facility reporting from Phoenix reported a reference interval for BUN ranging from 6-20 mg/dl. The third facility, reporting from Spokane, reported a reference interval for BUN of 6-24 mg/dl.
All were processed by the same lab company, processing the exact same test using the same test methodology. They were all processed during the exact same week. And yet they had completely different reference intervals. This is precisely the type of variance we would anticipate in a large laboratory system comprised of many different facilities.
Each reference interval is valid for the individual facility conducting the test.
Laboratory medicine has international standards for establishing reference intervals. These standards require each laboratory to create and validate its own reference interval based on the equipment used at the time, the instrument that produced the measurement, and the population of patients on whom it is measured. As such, within a nationwide laboratory system, several valid reference intervals for a given biomarker may exist simultaneously, depending on the laboratory that analyzed the specimen, the testing facility, and the patient population served.
This concept applies across all labs, not merely within a single lab. Each of LabCorp, Quest, regional labs, etc., establishes its own independent reference intervals. Therefore, when considering a test result relative to a threshold, a patient who has a biomarker level of 21 mg/dl is considered elevated in comparison to Phoenix’s 6-20 mg/dl reference interval and normal in comparison to Houston’s 8-27 mg/dl reference interval, despite the fact that both samples represent identically sampled physiological states.
It's a fair question: if lab reference ranges vary, why not just update our database more frequently to keep pace? The honest answer is that increasing the frequency of updates wouldn't solve the underlying issue. A lab like Labcorp can have multiple valid reference intervals in use across its network at the same time. Updating daily would still mean choosing one number to display, and that number would still differ from what prints on reports from other facilities within the same lab.
Both.
The reference range shown on your patient’s report reflects the validated range established by the laboratory performing the analysis.
The reference range displayed in Optimal DX reflects the laboratory's established range, as published on its website.
Since most major labs have numerous testing facilities, these two values may not necessarily be identical, and neither is incorrect.
The standard reference range helps facilitate understanding in the context of clinical interpretation. However, functional interpretation is based on physiologically derived optimal ranges, which remain constant regardless of which laboratory, analyzer, or regional facility processed the sample.
Physiological and clinically researched optimal ranges are based on physiology, not on the statistical distributions of a laboratory’s reference population. For this reason, it is unnecessary to reconcile the physiology-based optimal ranges against the Houston, Phoenix, or Spokane standard reference intervals.
Clinical interpretation via Optimal DX relies on physiology as opposed to the statistical reference intervals established by various laboratories. Standard reference intervals provide useful background information; however, optimal health remains unchanged regardless of geographic location.
Your patient may notice their “normal” lab results change when they obtain them from two separate locations. This provides an opportunity to educate your patient regarding why this occurs: the statistical reference range they observe relates to the facility that processed their sample, whereas Optimal DX utilizes physiologically based optimal ranges to evaluate your patient’s health status that do not vary with geographical location.
For LabCorp specifically, since it is one of the largest laboratories used by practicing physicians for Optimal DX-based clinical decision-making support, we obtain our standard ranges directly from LabCorp’s official website for each test for which LabCorp provides reference intervals. Reviewing those reference intervals is part of our continuous quality improvement process to maintain our database.