Interpreting pathology tests: results and reference intervals

Interpreting laboratory results requires more than relying on the laboratory to tell us whether the test is positive or on scanning the results for the laboratory’s asterisks indicating the abnormal results. Sometimes we want to know if a test reported as positive is a true positive for the problem being tested or a false positive in someone without the problem. We may also want to know how abnormal an abnormal result is and whether a difference between consecutive results indicates a real change (a ‘signal’) or background result variability (the ‘noise’). The clinical context should, of course, be taken into account when test results are being considered, and the laboratory’s interpretation should not be relied on completely.

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