Practice Practice Pointer

Explaining laboratory test results to patients: what the clinician needs to know

BMJ 2015; 351 doi: http://dx.doi.org/10.1136/bmj.h5552 (Published 03 December 2015) Cite this as: BMJ 2015;351:h5552
  1. Maurice John O’Kane, consultant chemical pathologist1,
  2. Berenice Lopez, consultant chemical pathologist2
  1. 1Altnagelvin Hospital, Western Health and Social Care Trust, Londonderry, UK
  2. 2Norfolk and Norwich University Hospitals Foundation Trust, Norwich, UK
  1. Correspondence to: M J O’Kane Maurice.OKane{at}westerntrust.hscni.net

The bottom line

  • Minor test abnormalities in well people may have no clinical relevance. By definition, 5% of healthy people will have test results that fall just outside the 95% healthy population reference interval

  • Consider the possibility of false positives and negatives: the predictive value of tests varies with different disease prevalence in different settings; if the index of suspicion is high, further tests may be warranted even if the result is negative

  • Outside of formal screening programmes, speculative screening tests in well asymptomatic people have little value and may result in over investigation and unnecessary treatment

Better understanding by patients of why tests are performed and what the results mean increases satisfaction with care.1 2 3 4 Patients increasingly have direct access to their test results through online portals. Although patients may discuss test results with family and friends or seek information on the internet,5 the responsibility for explaining test results lies with clinicians. Discussions must take into account the patient’s literacy and numeracy level, and clinicians should explain clearly what the results mean and how they influence treatment choices.

Why are tests performed?

It is crucial to understand why a test was done to understand the meaning of its result. The following are common reasons for testing:

  • Diagnosis: to confirm (or exclude) a specific diagnosis when suggestive symptoms or signs are present—for example, measurement of glycated haemoglobin in a patient with thirst and suspected type 2 diabetes

  • Monitoring: to monitor response to treatment (for example, prostate specific antigen in prostate cancer) or disease progression (estimated glomerular filtration rate in chronic kidney disease)

  • Risk stratification: to help assess disease risk and the need for preventive therapy—for example, lipid measurement to help quantify cardiovascular disease risk

  • Screening: undertaken in asymptomatic people to assess the risk of occult disease and the need for further confirmatory tests—for …

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