The role of testing: evaluating test results in a clinical context
The doctor is expected to evaluate all of the relevant findings – test reports plus information that he or she has obtained from you - before settling on a diagnosis and developing a treatment plan. Given the variability in testing and the potential for false results, no diagnosis should ever be made solely on the basis of a single laboratory test.
The clinician must always ask, ‘Do the test results fit with the other pieces of the puzzle?’
These other pieces include your clinical status (physical signs and symptoms) and your personal and family history. Pathology tests are not foolproof and can present an incomplete picture when not put into proper context. Careful evaluation and consideration of test findings increases the reliability of a diagnosis and reduces the chance of medical error.
If the results do not fit well with the clinical picture, some additional investigation may be required. A retest or alternative test may be requested when it is appropriate to confirm the findings.
What could make the test results invalid or inadequate?
Although laboratory testing must meet high standards for consistency and reliability, occasionally the test results are falsely negative or falsely positive since no test can be 100% sensitive and specific.
Fraser CG (1986). ‘Interpretation of Clinical Chemistry Laboratory data’ Blackwell Scientific Publications.