Can you review my laboratory results?

Laboratory Report Review: Essential Principles for Clinical Interpretation

When reviewing laboratory results, the most critical step is ensuring proper clinical context accompanies the request, as test interpretation fundamentally depends on the patient's clinical presentation, medications, and working diagnosis. 1

Core Elements Required for Meaningful Review

Patient Information and Clinical Context

• Patient demographics (age, sex, date of birth) must be clearly documented, as reference ranges vary significantly by age and physiological status 1
• Reason for testing should be explicitly stated on the requisition, as this directly influences result interpretation and determines whether values represent pathology versus physiological variation 1, 2
• Current medications and anticoagulation status are essential, as these can cause false positives/negatives or interfere with specific assays 1
• Timing of specimen collection relative to clinical events (acute illness, medication changes) helps distinguish transient from persistent abnormalities 1

Technical Quality Assessment

• Specimen adequacy including collection date/time, processing conditions, and any factors affecting sample quality must be documented 1
• Pre-analytical variables such as hemolysis, lipemia, or improper handling can significantly alter results and should be noted 1
• Method-specific limitations including limit of detection, analytical range, and potential interferences should be considered when interpreting borderline or unexpected values 1

Interpreting Abnormal Results: A Systematic Approach

Step 1: Verify Plausibility and Technical Validity

• Compare results to local reference ranges stated in the report, recognizing these are population-based and may not reflect individual baseline 1, 3
• Check for internal consistency between related parameters (e.g., if evaluating anemia, ensure hemoglobin, hematocrit, and red cell indices are concordant) 2
• Consider biological variation: Intraindividual variation is more common than laboratory error when repeat testing shows discrepant results 4, 3

Step 2: Apply Clinical Context

• Age-related physiological changes can alter certain values without representing pathology, particularly in elderly patients (>75 years) 5, 4

  • Alkaline phosphatase may elevate to 2.5× normal 5
  • Fasting glucose up to 135-150 mg/dL may be acceptable 5
  • ESR up to 40 mm/hr can be normal 5
  • Hemoglobin ≥11.0 g/dL (women) or ≥11.5 g/dL (men) is lowest acceptable 5
  • BUN up to 28-35 mg/dL may be physiologic 5
  • Normal creatinine can coexist with markedly decreased creatinine clearance 5, 4

• Medication effects must be systematically evaluated, as polypharmacy in complex patients causes more confusion than inadequate reference ranges 5, 6

Step 3: Determine Clinical Significance

• Distinguish screening from diagnostic testing: A single abnormal value in an asymptomatic patient requires different interpretation than the same value in someone with compatible symptoms 6, 3
• Assess magnitude of abnormality: Values just outside reference range have different implications than those markedly elevated 1
• Evaluate temporal pattern: Persistent abnormalities (confirmed on repeat testing ≥12 weeks apart) carry more weight than transient elevations 1

Common Pitfalls to Avoid

Over-interpretation of Borderline Values

• Do not overreact to apparently abnormal values by initiating inappropriate investigations or treatments 4, 6
• Reference intervals describe population diversity, not individual pathology—10% of healthy individuals will fall outside the "normal" range by definition 3
• Contextual tests (those requiring specific physiological conditions for interpretation) are particularly prone to misinterpretation when context is ignored 3

Under-appreciation of Pre-analytical Factors

• Specimen collection timing relative to medication administration can dramatically affect results (e.g., anticoagulants interfering with coagulation assays) 1
• Sample handling errors are more common than analytical errors in modern laboratories 1

Failure to Integrate Multiple Data Points

• Isolated abnormalities should prompt review of related parameters rather than immediate clinical action 2, 6
• Discordant results between clinical presentation and laboratory findings warrant repeat testing or alternative explanations before assuming disease 4, 3

Reporting and Documentation Requirements

Essential Report Elements

• Patient identifiers and unique specimen numbers 1
• Test methodology and performance characteristics (sensitivity, specificity, limitations) 1
• Reference intervals appropriate for the patient's demographics 1
• Interpretive comments when results are complex or require clinical correlation 1
• Contact information for laboratory personnel to facilitate discussion of complex cases 1

Quality Assurance Considerations

• Laboratories must participate in proficiency testing programs and document quality assurance activities 1
• Result verification should include review of quality control data and instrument calibration status 1

When to Seek Laboratory Consultation

• Unexpected results that don't fit the clinical picture warrant discussion with laboratory staff before clinical action 2, 6
• Complex cases benefit from laboratory-clinician interaction to optimize test selection and interpretation 1
• Rare diseases or unusual presentations may require specialized testing or alternative methodologies 1