Trusted-source health topic
Why Reference Ranges Can Differ
Reference ranges can differ because laboratories may use different methods, equipment, units, and reference populations.
Why is this important?
Understanding the purpose and limits of laboratory information can support a more informed conversation with a qualified healthcare professional.
How laboratory testing relates
Results are best compared with the range printed by the laboratory that performed the test. Cross-laboratory comparison may require professional review.
Before testing
Preparation is test-specific. Follow the instructions given for the exact test and contact the laboratory if fasting, timing, medicines, or specimen collection is unclear. Do not stop medicines unless a qualified professional tells you to.
Sources & further reading
- MedlinePlus, U.S. National Library of Medicine: How to Understand Your Lab Results
External authoritative patient reference · Verified 2026-08-10