Variation in Laboratory Reports: Causes other than Laboratory Error

When a sample of an individual is measured at different times at the same or different clinical laboratory, the results are always different, even the state of health of an individual is the same. This disparity in the results from clinical laboratories might confuse diagnosing, treating, and monitoring disease. Patients and healthcare professionals usually interpret these differences as laboratory errors. However, this might not always be the case, because laboratory test results are highly variable and are neither consistent nor comparable due to several reasons other than laboratory error, namely pre-analytical variation, biological variation, and analytical variation.