normal and referance range use, how make, introduction, different types, application,

1. Normal & Reference range

2. Introduction
The reference range is also termed the reference interval.
DEFINATION
which is defined by reference limits and obtained from measurements on the
reference population for a particular test
OR
A pair of medical decision points that span the limits of results expected for
a given condition.
OR
When making any clinical measurement, for example weighing a patient or
measuring pulse rate, results are interpreted by reference to what is normal.

3. What is Reference range
 Reference range include all the data points that define the range of
observations (e.g., if the interval is 5–10, a patient result of 5 would be
considered within the interval).
 The upper and lower reference limits are set to define a specified
percentage (usually 95%) of the values for a population; this means that a
percentage (usually 5%) of patients will fall outside of the reference interval
in the absence of any condition or disease.
 Laboratory test data are used to make medical diagnoses, assess physiologic
function, and manage therapy.
 When interpreting laboratory data, clinicians compare the measured test
result from a patient with a reference interval.
 Reference intervals are sometimes erroneously called “normal ranges.” While
all normal ranges are in fact reference intervals, not all reference intervals
are normal ranges .

4. Why establishing a reference interval:
A reference interval is established when
there is no existing analyte or methodology in
the clinical or reference laboratory with
which to conduct comparative studies.

5. To establish a reference range study:
 Define an appropriate list of biological variations and
analytic interferences from medical literature.
 Choose selection and partition (e.g., age or gender)
criteria.
 Complete a written consent form and questionnaire to
capture selection criteria.
 Categorize the potential reference individuals based on
the questionnaire findings.
 Exclude individuals from the reference sample group
based on exclusion criteria.

6.  Define the number of reference individuals in
consideration of desired confidence limits and statistical
accuracy.
 Standardize collection and analysis of reference
specimens for the measurement of a given analyte
consistent with the routine practice of patients
 Inspect the reference value data and prepare a histogram
to evaluate the distribution of data.
 Identify possible data errors and/or outliers and then
analyze the reference values.
 Document all of the previously mentioned steps and
procedures.

7. What is normal range ?
 Normal range
 choice between defining an ‘ideal state’ or
determining an ‘average’ state considered
normal range
 more practical to analyze ‘average’ state
with respect to a biological parameter
results in a symmetric (Gaussian) distribution
 a normal range is the range in concentration of 95%
of the normal (healthy) population.

8. Factors that affect the reference range
 Various quite normal physiological factors may
need to be taken into account when interpreting
laboratory test results.
 Test results may be affected by:
• Age of the patient.
• Sex of the patient.
• Pregnancy.
• Time of the day the sample was collected.

9. For example,
 blood urea concentration rises with age and blood
hormone levels are different among adult males
compared with adult females.
 Pregnancy can affect the results of laboratory
tests of thyroid function.
 Blood glucose levels fluctuate throughout the day.
 Alcohol and many drugs can affect blood test
results in a variety of ways.

10. The results of measuring the concentration
of hypothetical substance X in the blood of
a large population of apparently healthy
individuals (the reference population), and
those with a hypothetical disease Y.
Since the blood concentration of substance
X is usually raised in those suffering
disease Y, it is used as a blood test to
confirm the diagnosis among those with
symptoms of Y.
From the graph it can be seen that the
concentration of X among apparently
healthy individuals ranges from 0.3 to 8.0
mmol/L

11.  Reference interval use can be grouped into
three main categories:
 diagnosis of a disease or condition
 monitoring of a physiologic condition
 therapeutic management

12. diagnosis of a disease or condition

13. monitoring of a physiologic condition

14. THERAPEUTIC RANGE
 It is the concentration range of drug in plasma where the
drug has been shown to be efficacious without causing
toxic effects in most people.

15. Referance range of routne biochemistry
parameter

16. Thank you