Levels of control are described as which categories?

• A. Normal, Pathological
• B. Normal, Abnormal
• C. Basic, Advanced
• D. Low, High

Answer: (A)

Levels of control in clinical chemistry are designed to represent values seen in healthy individuals and in disease states. The aim is to verify that the assay gives accurate results across the clinically relevant range, not just near the reference value. A normal control sits within the reference interval, ensuring the method handles typical samples correctly, while a pathological control lies outside that interval, testing the assay’s ability to flag abnormal results. This combination—normal and pathological—best reflects the practical need to monitor performance across both healthy and disease-range values. Other descriptors like abnormal are synonymous, but the standard terminology used in quality control is normal and pathological, while terms such as basic/advanced or low/high don’t convey the same clinically relevant distinction.