Clinical Laboratory Quality Management
Levels of Quality
Laboratory quality can be categorized into three levels:
- Analytical Data Quality: Ensuring accurate calibration and passing inspections.
- Analytical Method Quality: Responsibility of the kit providers.
- Clinical Laboratory Quality: Overall quality management within the laboratory.
Quality Plan Essentials
Every laboratory requires a comprehensive quality plan to guarantee reliable reports. Essential components include:
- Functional Organization: Organizing laboratory activities by shifts (activities, time, staff, etc.).
- Standard Operating Procedures (SOPs) Manual: A comprehensive guide detailing all laboratory techniques.
- Apparatus Inventory: A detailed list of all laboratory equipment.
- Hygiene and Safety Manual: Guidelines for maintaining a safe laboratory environment.
- First Aid Manual: Procedures for handling medical emergencies.
- Reagent and Medical Supply Catalog: A list of reagents and supplies for daily use.
- Equipment Manual: Instructions for setup, calibration, maintenance, and control of analytical equipment.
- User-Generated Analytical Records: Reports, pre-registrations, etc.
Quality Control
Internal Quality Control
Utilizes certified samples to monitor technical parameters and methods. Proper handling and preparation are crucial. Frequency of internal control checks should be determined by laboratory management and documented in a written plan.
External Quality Control
Managed by an external laboratory or institution. Acts as a central regulator, ensuring compliance with specific standards. Organizations like the Spanish Society of Clinical Chemistry and other registered reference laboratories play a key role.
Errors in Analytical Techniques
An error is an act involving a failure or mistake before or during an analytical technique. Statistically, errors are categorized based on when they occur:
Pre-analytical Errors
Occur before analysis, typically during sample collection and processing. Examples include:
- Defective blood samples
- Sample misidentification
- Contaminated urine samples
- Incorrect sample storage
- Improperly prepared or damaged reagents
- Incorrect patient instructions for sample collection
Analytical Errors
Occur during the determination of biochemical parameters. Two main types:
- Random Errors: Due to specific, unpredictable causes, affecting reproducibility but not the mean. Possible causes include miscalibrated equipment, temperature variations, unstable equipment, and staff errors.
- Systematic Errors: Persistent errors that shift the arithmetic mean. Random errors can become systematic if not addressed promptly.
Post-analytical Errors
Occur after analysis, often related to laboratory computerization failures.
Technical Terminology
- Technique: The scientific principle (chemical, physical, or physicochemical) used to provide information about a parameter in a biological sample.
- Method: The adaptation of a technique to measure a specific parameter in a particular biological specimen. Instructions for performing a method are known as the protocol, analytical procedure, or operating mode.
- Analytical Range: The concentration range within which a method can be applied without modification.
- Accuracy: The agreement between the measured value and the true value.
- Precision: The agreement between multiple determinations of the same sample under the same conditions. Expressed as standard deviation.
- Limit of Detection (LOD) and Limit of Quantification (LOQ): The lowest concentration that can be detected or quantified, respectively.
- Interference: The influence of other sample components on the determination of a specific analyte, leading to inaccurate results. Types of interference are specified in reagent kits.
- Specificity: The ability of a method to measure only the target analyte.