Laboratory Test Limits

In medical testing, "lower" and "upper limits" define the normal range of acceptable test results.

Lower Limit
- Definition: Minimum value considered normal for a specific test.
- Indication: Results below the lower limit may suggest a potential health issue.
- Example: Glucose levels below 70 mg/dL may indicate hypoglycemia.

Upper Limit
- Definition: Maximum value considered normal for a specific test.
- Indication: Results above the upper limit may suggest a potential health issue.
- Example: Cholesterol levels above 200 mg/dL may indicate hypercholesterolemia.

Contextual Understanding

- Reference Ranges: Limits are part of reference ranges established by clinical studies.
- Interpretation: Results outside the limits do not necessarily indicate a problem, but may warrant further evaluation.
- Variability: Reference ranges may differ between laboratories and populations. Use ranges provided with the lab report.

Clinical Significance

- Abnormal results should be interpreted in the context of overall health, symptoms, and medical history.
- Healthcare professionals assess the significance of abnormal results and determine appropriate actions.

Examples

- Complete Blood Count (CBC)
- Hemoglobin: Lower limit may vary based on sex.
- White Blood Cells: Upper limit may indicate infection or inflammation.
- Lipid Panel
- LDL Cholesterol: Upper limit may indicate increased risk for cardiovascular disease.