Published: 27 Oct 2024

Understand your blood test results.
What are pitfalls?

Understanding blood test results can be challenging, as there are several pitfalls that can lead to misinterpretation or unnecessary worry. Here are some common pitfalls to be aware of:

1. Over-Reliance on Reference Ranges
Pitfall: Interpreting every slight deviation from the reference range as an indication of illness. Reference ranges are typically based on 95% of healthy individuals, so 5% of healthy people may naturally fall outside these ranges.
Solution: Slightly abnormal results, especially if close to the reference range, are not always indicative of disease and should be interpreted within the broader context of symptoms and health history.

2. Interpreting Single Results in Isolation
Pitfall: Looking at a single test result without considering related values can lead to misinterpretation. For instance, a low hemoglobin level alone might suggest anemia, but the cause might be better understood by also looking at red blood cell indices and iron levels.
Solution: Consider test results as part of a broader pattern, looking at related tests or panels to get a clearer picture.

3. Not Accounting for Variability in Labs and Equipment
Pitfall: Assuming that all lab results are directly comparable, even if they come from different labs or testing equipment.
Solution: When tracking a specific value over time, ideally use the same laboratory. Small variations are normal between labs due to equipment, testing methods, and population differences.

4. Ignoring Biological Variability
Pitfall: Blood values can vary throughout the day and can be influenced by recent meals, hydration, exercise, stress, or medications.
Solution: Try to follow pre-test instructions (e.g., fasting if required) and recognize that repeat testing may sometimes be needed to confirm an outlier result.

5. Mistaking "Normal" for "Optimal"
Pitfall: A value within the "normal" range isn't always optimal for everyone. For example, "normal" cholesterol levels might still be high for a person at risk of heart disease.
Solution: Work with a healthcare provider to determine what ranges are optimal for you, especially if you have specific health conditions or goals.

6. Not Considering Age, Gender, and Other Individual Factors
Pitfall: Interpreting results without considering demographic factors that can affect normal ranges. For example, hemoglobin levels generally run lower in women than men, and kidney function may naturally decline with age.
Solution: Ensure results are interpreted in light of age, gender, and overall health status.

7. False Positives and False Negatives
Pitfall: Screening tests aren't perfect and can sometimes show abnormal results when no disease is present (false positive) or normal results when disease is present (false negative).
Solution: If a result is surprising or concerning, repeat testing or follow-up tests may help to clarify the situation. Avoid jumping to conclusions based on a single abnormal result.

8. Assuming All Results Indicate Current Health Status
Pitfall: Some tests, like hemoglobin A1c for blood sugar control, reflect longer-term averages, while others, like blood glucose, can fluctuate daily.
Solution: Understand which tests are immediate (e.g., glucose) versus cumulative (e.g., A1c) and interpret them accordingly.

9. Misinterpreting Sensitivity and Specificity
Pitfall: Some tests are more prone to false positives or negatives due to their inherent sensitivity and specificity. For example, highly sensitive tests are good for ruling out disease but may show false positives.
Solution: Ask about the sensitivity and specificity of any test and whether further confirmatory testing is needed if a test result is borderline.

10. Not Following Up on Abnormal Results
Pitfall: Assuming a mildly abnormal result is "normal for me" without seeking professional advice. Ignoring persistent or significantly abnormal results can lead to delayed diagnosis.
Solution: Always follow up with a healthcare provider on any abnormal result, especially if the abnormality is recurrent or coupled with symptoms.

Summary
Blood test results should be interpreted in light of your health history, symptoms, and individual factors, ideally with guidance from a healthcare professional. Avoid overreacting to slight deviations and be cautious about making assumptions without expert input, especially with complex or critical tests.