1. Reference ranges – population-based (definition, reference group, reference individuals, choice of statistical method, disadvantages) and individual (establishment, advantages).

Analytical reliability of clinical laboratory methods – criteria. Reference ranges – populational constructed (definition, reference groups, reference status, reference condition, choice of statistical method, performance, disadvantages) individual (performance, advantages).

Clinical laboratory is involved in detection, diagnosis, prognosis, patient management, therapy monitoring. It also ensures: 1) that only analytical methods with high analytical and diagnostical reliability are introduced. 2) Establishing reference ranges of the laboratory parameters 3) Education of the laboratory personnel, developing the requirements in preanalytical and postanalytical stage

Criteria:

• Quality Control (QC): the measures taken in each test to ensure test is working properly. To ensure that the results generated by the test are correct.
• Quality Assurance (QA): overall measures taken to ensure that the final results reported by the lab are correct. To ensure that the right test is carried out on the right specimen, and that the right result and right interpretation is delivered to the right person at the right time
• Quality Assessment: to determine the quality of the results generated by the lab. Can be internal or external. Internal quality control involves the day-to-day monitoring of lab activities. It helps ensure systematic and random error are caught before patient data are released. External quality control, on the other hand is a way by which labs can compare their performance to other labs that perform the same analysis.

Definition:

Reference ranges – a set of laboratory test values, obtained from an individual or from a group in a define state of health. They are obtained under specific conditions (determination of the reference population, collection of the biological material, sample method, specific mathematical approach for analysing the results

Individual reference values: obtained from an individual in a define state of health, after statistical data processing

Group/population/ reference values - obtained from a group in a define state of health, after statistical data.

Reference condition:

Individuals, selected according specific criteria, which include age, sex, conditions for collecting specimen, a define state of health of the individual.

Steps in establishing a reference range:

1. Select the analyte for which the reference range is to be established
2. Define the reference population. Demographically, it should match the population whose laboratory results will be compared to this reference range.
3. Choose a sampling method
4. Collect, process, and test the specimens.
5. Analyse the results, Organize the results and Eliminate outliers
6. Select a method for calculating the reference range- there are two basic methods: parametric and non-parametric