How do I interpret abnormal lab results?

From the Guidelines

When interpreting abnormal lab results, it is crucial to consult with a healthcare provider to understand the context and implications of the results, as they can provide personalized guidance and recommendations. Abnormal lab results do not always indicate a serious problem and may be due to temporary factors such as medications, food, exercise, or lab errors 1. The extent of liver blood test abnormality is not necessarily a guide to clinical significance, and this is determined by the specific analyte that is abnormal and the clinical context 1.

Key Considerations

• Abnormal lab results should only be interpreted after review of previous results, past medical history, and current medical condition 1.
• The initial investigation for potential liver disease should include bilirubin, albumin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), and γ-glutamyltransferase (GGT), together with a full blood count if not already performed within the previous 12 months 1.
• Patients with abnormal liver blood tests should be considered for investigation with a liver aetiology screen irrespective of level and duration of abnormality 1.

Recommendations

• Abnormal liver blood test results should be interpreted in the context of the patient's clinical scenario, and a decision about the need for further diagnostic evaluation and/or the appropriate evaluation can best be made based on the specific clinical scenario of the individual patient 1.
• Adults with NAFLD should undergo risk stratification to determine the extent of their liver fibrosis, and first-line testing should use either fibrosis-4 (FIB-4) or NAFLD Fibrosis Score (NFS) 1.
• It is essential to keep track of lab results over time to identify patterns and to remember that lab tests are just one tool in evaluating health, and results should be interpreted alongside symptoms, medical history, and physical examination findings 1.

From the FDA Drug Label

The MIC values should be interpreted according to the following criteria: For testing aerobic microorganisms other than Haemophilus influenzae , Haemophilus parainfluenzae, and Neisseria gonorrhoeaea: MIC (μg/mL)Interpretation ≤ 1 Susceptible (S) 2 Intermediate (I) ≥ 4 Resistant (R)

To interpret abnormal lab results, you need to understand the MIC (Minimum Inhibitory Concentration) values and the corresponding interpretation.

• Susceptible (S): The pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable.
• Intermediate (I): The result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated.
• Resistant (R): The pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected. The lab results should be interpreted based on the specific microorganism being tested and the test method used, such as broth microdilution or disk diffusion 2. Key points to consider when interpreting lab results:
• MIC values: Compare the MIC value to the interpretive criteria to determine if the microorganism is susceptible, intermediate, or resistant.
• Test method: Ensure that the test method used is appropriate for the microorganism being tested.
• Quality control: Verify that the laboratory has performed quality control tests to ensure the accuracy of the results.

From the Research

Interpreting Abnormal Lab Results

To interpret abnormal lab results, it is essential to consider several factors, including:

• The reference range for the specific test, as noted in 3
• The patient's medical history and current symptoms, as discussed in 4 and 5
• The potential for laboratory-associated and diagnostic errors, as highlighted in 6
• The need for clear communication of lab results to patients and families, as emphasized in 7

Factors Affecting Lab Results

Several factors can affect lab results, including:

• Analytical uncertainty, as discussed in 3
• Pre- and post-analytical phases of the testing cycle, as mentioned in 6
• Patient conditions and handling of specimens, as noted in 3
• Systematic error and analytical variation, as highlighted in 3

Communicating Lab Results

Effective communication of lab results is crucial, and can be achieved by:

• Providing a clear takeaway message for each result, as recommended in 7
• Signaling whether differences are meaningful or not, as suggested in 7
• Providing thresholds for concern and action, as recommended in 7
• Individualizing the frame of reference by allowing custom reference ranges, as proposed in 7

Clinical Considerations

Clinicians should be aware of the potential for lab results to be incorrect or misleading, and should:

• Evaluate the possibility of laboratory-associated and diagnostic errors, as discussed in 6
• Consider the patient's medical history and current symptoms when interpreting lab results, as noted in 4 and 5
• Use lab results in conjunction with physical assessment findings to inform nursing care, as emphasized in 5