"Are my Laboratory Results Normal?" Considerations to be Made Concerning Reference Intervals and Decision Limits

Area of Science:

• Clinical Biochemistry
• Medical Diagnostics
• Laboratory Medicine

Background:

• Reference intervals are essential for interpreting laboratory test results.
• Distinguishing between reference intervals and decision limits is often unclear in clinical practice.
• Accurate interpretation relies on understanding the basis of these numerical values.

Purpose of the Study:

• To clarify the distinct concepts of reference intervals and clinical decision limits.
• To explain the physiological basis of reference intervals versus the disease-oriented nature of decision limits.
• To aid clinicians in the correct interpretation of diagnostic test results.

Main Methods:

• Conceptual analysis of reference intervals and decision limits.
• Illustration of differences using examples.
• Discussion of various methods for defining decision limits (Bayesian, epidemiological, clinical experience).

Main Results:

• Reference intervals represent the biological variation in a healthy, well-defined population.
• Decision limits are established using diverse approaches, focusing on disease states or health risks.
• A clear distinction exists between physiological reference ranges and clinically applied decision thresholds.

Conclusions:

• Reference intervals are rooted in physiology, while decision limits are linked to pathology or risk assessment.
• Clinicians must recognize the fundamental differences to avoid misinterpretation of patient data.
• Proper application of these concepts improves diagnostic accuracy and patient care.