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Dr. Adel M. Assiri Faculty of Medicine Department of Biochemistry Umm Al-Qura University

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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. 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. 4

Expression of Biochemical Results Biochemical analysis are : Quantitative, semi-quantitative, Qualitative Results are reported as concentration, usually in terms of number of : 5

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 ) 6

Biochemical Measurements Vary for Two Reasons: 1. Analytical Variation ( Pre-, Analytical, Post- ) 7

2. Biological Variation :-  Sex  Sex  Age  Age  Diet  Diet  Time  Time  Stress  Stress  Exercise  History  Pregnancy  Menstrual Cycle  Drugs 8

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. 9

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. 10

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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 ). 13

1. Internal 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. 14

2. 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. 15

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