# How are reference range values established?

## How are reference range values established?

Individual variability: References ranges are usually established by collecting results from a large population and determining from the data an expected average (mean) result and expected differences from that average (standard deviation).

## What is the main purpose for the use of reference ranges?

Reference intervals are the most common decision support tool used for interpretation of numerical pathology reports. As laboratory results may be interpreted by comparison with these intervals, the quality of the reference intervals can play as large a role in result interpretation as the quality of the result itself.

What is a reference value?

Listen to pronunciation. (REH-frents VAL-yooz) In medicine, a set of values that a doctor uses to interpret a patient’s test results. The reference values for a given test are based on the results that are seen in 95% of the healthy population.

### Why are reference ranges different?

A reference range can vary between different laboratories when a collection of people who are considered ‘normal’ are used to establish a reference range for a given blood test. Complex mathematics are applied to allow for a natural variation within this chosen collection of people and therefore the reference range.

### What is normal hemoglobin range?

The normal range for hemoglobin is: For men, 13.5 to 17.5 grams per deciliter. For women, 12.0 to 15.5 grams per deciliter.

How do you find reference values?

When assuming a normal distribution, the reference range is obtained by measuring the values in a reference group and taking two standard deviations either side of the mean. This encompasses ~95% of the total population.

#### How to determine reference intervals for clinical laboratory?

This may reflect a large prevalence of subclinical disease within the selected population or subgroup-related differences in normal ranges. The latter requires partitioning of test subjects by sex, age, race, and other factors. Partitioning by sex is relatively easy (select a minimum of 120 males and 120 females).

#### How is a reference interval ( RI ) established?

It has been recommended that an RI be established by selecting a statistically sufficient group (a minimum of 120) of healthy reference subjects. However, it is noted in the guideline that “Health is a relative condition lacking a universal definition.

How to obtain a valid group of reference subjects?

Recruiting a valid group of reference subjects and obtaining informed consent in today’s environment is costly, time-intensive, and virtually an impossible task for most laboratories.

## How is the accuracy of reference intervals assessed?

The accuracy was assessed by the comparability of reference intervals as calculated by the new method with published peer-reviewed studies, and reproducibility was assessed by the comparability of 2 sets of reference intervals derived from 2 different data sets.

09/11/2020