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Interpretation of Laboratory Results . Umm Al-Qura University . Faculty of Medicine . Department of Biochemistry . Dr. Adel M. Assiri . TOPICS :- . Introduction .
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Interpretation of Laboratory Results Umm Al-Qura University Faculty of Medicine Department of Biochemistry Dr. Adel M. Assiri
Introduction Interpretation of Laboratory Results means understanding the meaning of numbers that we obtain when tests are done. This is important if the correct diagnosis is to be made, or if the patients treatment is to be changed.
Results are reported as concentration, usually in terms of number of : Expression of Biochemical Results Biochemical analysis are : Quantitative, semi-quantitative, Qualitative
Mole in one liter ( mol / l ) Millimoles in one liter ( mmol / l ) Micromole in one liter ( umol / l ) Unite in one liter ( U / l ) Grams in one liter ( g / l ) Milligrams in one liter ( mg / l ) Kilopascals ( kpa )
VariationofResults Biochemical Measurements Vary for Two Reasons: Analytical Variation ( Pre-, Analytical, Post- )
Exercise History Pregnancy Menstrual Cycle Drugs Biological Variation :- Sex Age Diet Time Stress
ReferenceRanges Biochemical test results are usually compared to a reference range considered to represent the normal healthy state. Most Reference Ranges are made by including 95 % of the values found in healthy volunteers. Therefore, 5 %of the population will have a result out the reference range.
There is often a degree of overlap between the disease state and normal value. A patient with an ABNORMAL result who is found NOT to have the disease is a false positive. A patient who has the disease but has NORMAL result is a false negative.
Quality Control ( Q C ) To monitor Performance of Assays ( Tests ) using Quality control Samples ( with Known values) to give Reassurance that the Method is Performing Correctly with the patient's Specimens ( unknown values ).
There are Two Types of QC :- They are analysed every day, or every time a test is run. The expected values are known and the obtained values are compared to monitor the performance. Internal QC
External QC Identical Samples made by a central Lab. Or health authority are distributed to laboratories to be analysed then the results are sent to be compared to check the performance of all Labs.