How should abnormal lab results be interpreted in the context of a patient's clinical presentation and medical history?

From the Guidelines

Abnormal lab results should be interpreted with caution, considering the patient's clinical presentation, medical history, and the limitations of laboratory tests, as evidenced by studies showing that most abnormal results are clinically unimportant 1. When interpreting lab results, it's essential to consider the broader context, including the patient's symptoms, medical history, and previous lab values.

• Begin by evaluating whether the abnormal value aligns with the patient's known conditions and symptoms.
• Compare current results with previous values to identify trends or acute changes.
• Consider pre-analytical factors that might affect results, such as medications, fasting status, or sample collection issues, as highlighted in the study by Dolan and Mushlin 1.
• Evaluate the degree of abnormality, recognizing that mild deviations may require monitoring while significant abnormalities often warrant immediate action.
• Remember that lab reference ranges represent population norms, not diagnostic thresholds, and some patients have personal baselines outside these ranges.
• Consider the test's sensitivity and specificity, as false positives and negatives can occur, as noted in the studies by Ferguson and Dudleston, and White and Barraclough 1. This comprehensive approach helps prevent unnecessary interventions for clinically insignificant abnormalities while ensuring truly concerning results receive appropriate attention, ultimately prioritizing the patient's morbidity, mortality, and quality of life.
• The study by Tintinalli et al 1 emphasizes the importance of a thorough medical examination, including a neurologic examination, to identify potential medical issues that may be missed if relying solely on laboratory tests. By taking a thoughtful and multi-faceted approach to interpreting abnormal lab results, clinicians can provide more effective and patient-centered care.

From the FDA Drug Label

In controlled clinical trials of patients with CKD comparing higher hemoglobin targets (13 - 14 g/dL) to lower targets (9 – 11.3 g/dL), epoetin alfa and other ESAs increased the risk of death, myocardial infarction, stroke, congestive heart failure, thrombosis of hemodialysis vascular access, and other thromboembolic events in the higher target groups Using ESAs to target a hemoglobin level of greater than 11 g/dL increases the risk of serious adverse cardiovascular reactions and has not been shown to provide additional benefit A rate of hemoglobin rise of greater than 1 g/dL over 2 weeks may contribute to these risks

Interpretation of Abnormal Lab Results:

• Abnormal lab results, such as hemoglobin levels above 11 g/dL, should be interpreted with caution in the context of a patient's clinical presentation and medical history.
• A rapid increase in hemoglobin levels (greater than 1 g/dL over 2 weeks) may indicate an increased risk of cardiovascular reactions and mortality.
• The patient's underlying condition, such as chronic kidney disease (CKD), and coexistent cardiovascular disease should be taken into account when interpreting lab results.
• Key Considerations:
  • Hemoglobin targets should be individualized based on the patient's clinical condition and medical history.
  • ESAs, such as epoetin alfa, should be used with caution in patients with CKD and a history of cardiovascular disease.
  • Regular monitoring of lab results, including hemoglobin levels, is essential to minimize the risk of adverse cardiovascular reactions 2

From the Research

Interpreting Abnormal Lab Results

Abnormal lab results can be challenging to interpret, especially in the context of a patient's clinical presentation and medical history. Several studies have investigated how patients and clinicians interpret laboratory test results, highlighting the need for clear and effective communication.

• Patients often have difficulties understanding and acting upon clinical data presented in patient portals, leading them to seek online resources for guidance 3.
• The presentation of laboratory test results in patient portals can influence patients' risk interpretation and visual search behavior, with visual cues improving patients' abilities to correctly interpret results 4.
• Clinicians' interpretation of clinically significant changes in consecutive laboratory test results can be inconsistent and may not align with reference change values (RCV), highlighting the need for laboratories to guide clinicians on RCV for better decision-making 5.

Factors Affecting Interpretation

Several factors can affect the interpretation of laboratory test results, including:

• The patient's medical history and clinical presentation 6.
• The analytical and biological variation of laboratory tests 5.
• The use of reference change values (RCV) to determine significant changes between test results 5.
• The presentation of test results, including the use of visual cues and graphical displays 4.

Implications for Patient Care

The interpretation of abnormal lab results has significant implications for patient care, including:

• The need for clear and effective communication between patients, clinicians, and laboratories 3, 4.
• The importance of considering the patient's medical history and clinical presentation when interpreting test results 6.
• The potential for misinterpretation of test results, which can lead to delayed or inappropriate treatment 4, 5.