How should I review and manage abnormal medical test results?

Managing Abnormal Medical Test Results: A Systematic Approach

Key Recommendation

When reviewing abnormal test results, clinicians should have a predetermined plan for responding to unexpected findings, discuss results with patients, and use the information to improve patient safety rather than dismissing patients from care based solely on test results. 1

Initial Assessment of Abnormal Results

Verify Test Validity

• Confirm that quality control measures were met during testing
• Check that appropriate controls (internal and external) were properly processed 1
• Verify that preanalytic variables (sample collection, handling, timing) were appropriate 1

Interpret Clinical Significance

1. Evaluate concordance with clinical presentation

   • Compare results with patient's history and physical examination findings 1
   • Consider whether abnormal results explain the patient's symptoms or condition
   • Determine if results are expected based on known medical conditions

2. Consider technical factors

   • Assess for potential false positives or false negatives
   • For immunoassay-based tests (like drug screens), recognize limitations in specificity 2
   • For low-level positive results, consider confirmatory testing with more specific methods (e.g., GC-MS or LC-MS/MS) 2

Management Algorithm for Abnormal Results

Step 1: Classify the Result

• Critical value: Result indicating immediate life-threatening condition requiring urgent intervention
• Clinically significant abnormality: Result requiring action but not immediately life-threatening
• Borderline or mildly abnormal: Result outside reference range but of uncertain clinical significance
• Expected abnormality: Result consistent with known diagnosis or treatment

Step 2: Communicate with Patient

• Explain the purpose of the test and expected results before ordering 1
• When discussing unexpected results:
  • Provide context about what the test measures
  • Explain the significance of the abnormality
  • Avoid alarming language for minor abnormalities
  • Give patients opportunity to provide additional information that might explain results 1

Step 3: Determine Next Actions

For critical values:

• Immediate clinical intervention
• Urgent follow-up testing if needed to confirm diagnosis

For clinically significant abnormalities:

• Consider confirmatory testing if initial result could be false positive
• Implement appropriate treatment changes
• Schedule timely follow-up

For borderline abnormalities:

• Consider repeat testing to confirm persistence
• Evaluate in context of other clinical findings
• Monitor over time if clinically appropriate

Special Considerations for Specific Test Types

Urine Drug Testing

• Recognize limitations of immunoassay-based drug screens:

  • Standard immunoassays lack specificity to distinguish between structurally similar compounds 2
  • False positives can occur due to cross-reactivity with medications or foods
  • Detection windows vary by substance (1-3 days for most opioids, 1-30+ days for cannabis) 2

• When unexpected drug test results occur:

  • Discuss with patient before ordering confirmatory testing 1
  • Consider timing of medication administration relative to testing
  • Use confirmatory testing (GC-MS or LC-MS/MS) for definitive identification 2
  • Never dismiss patients from care based solely on urine drug test results 1

Hormone Receptor Testing in Breast Cancer

• For estrogen receptor (ER) testing results:
  • Follow standardized reporting protocols based on percentage of cells staining and intensity 1
  • For low positive results (1-10% cells staining), recognize limited data on endocrine therapy benefit 1
  • Ensure proper controls were included in testing 1

Molecular Testing Results

• For cell-free DNA analyses:
  • Verify tumor fraction estimation was included 1
  • Consider potential sources of variants (tumor vs. clonal hematopoiesis) 1
  • Flag unexpected findings for discussion with a Molecular Tumor Board 1

Pitfalls to Avoid

1. Overreliance on routine testing

   • Extensive routine laboratory testing has low yield and high false positive rates 1
   • Laboratory testing should be guided by clinical evaluation rather than performed routinely 1

2. Failure to consider test limitations

   • All tests have limitations in sensitivity and specificity
   • Recognize that negative results don't always rule out conditions if test sensitivity is low

3. Inappropriate patient management based on results

   • Avoid dismissing patients from care based solely on test results 1
   • Consider the complete clinical picture when making management decisions

4. Poor communication with patients

   • Failure to explain test purpose and potential implications before ordering
   • Not discussing unexpected results in a clear, non-judgmental manner

Follow-up and Documentation

• Document all abnormal results and actions taken
• Ensure appropriate follow-up testing is scheduled
• Communicate results and plans with other healthcare providers involved in patient care
• Create systems to track pending results and ensure they are reviewed

By following this systematic approach to abnormal test results, clinicians can ensure appropriate interpretation, management, and follow-up, ultimately improving patient safety and outcomes.