7 - clinical biochemistry Flashcards
Define precision
The reproducability of a measurement
Define accuracy
how close a measurement is to the true value
Define analytical sensitivity
How little of an analyte can be detected by an assay
Define analytical specificity
The ability of an assay to discriminate between the requested analyte and other similar or interfering substances
What are some things that need to be carried out when processing a request of a biochemical test?
Correct specimen and completed biochemistry form
Appropriate information to ensure the correct test
Bar coding to ensure the correct sample identify
How do labs ensure quality assurance internally ?
They test the assays daily and compare test results
How do labs ensure quality assurance externally?
Identical samples are distributed and the lab’s result is compared the to the true value and the values from other labs
What is a reference range?
the set of values for a given test that incorporates 95% of the normal population
How is a reference range calculated?
mean +/- 2SD
What is a false positive?
When a result lays outside of the reference range despite the person being healthy
What is a false negative?
When a patient has a disease, but their results lies with in the reference range/ the result is ‘normal’
What are some biological factors that can affect biochemical results
Gender, diet, time of day, stress, anxiety, menstrual cycle and strenuous exercise
What are some issues with sampling that can impact biochemical results
Difficulty sampling - can lead to pseudohyperkaleamia
Not having enough of a sample
Errors in timing
Using an incorrect specimen container
Inappropriate sampling site - e.g. downstream from an I.V drip
Incorrect specimen storage
What is tested when you test Us and Es
Urea, creative and electrolytes (potassium, sodium, chloride and bicarbonate)
Why would you measure urea and creatine?
To indicate Kinney function. They can also indicate dehydration,
