Biochemistry Tests Flashcards
What is accuracy?
How close the results are to the actual ‘true’ value
What is precision?
The reproducibility of an analytical result.
What is quality control?
A way of examining results to make sure they are accurate and precise
What is internal quality control?
A control technique where you know what the results should be therefore the results can be compared with this value.
What is an external quality control?
This is circulated by an external lab and the expected results aren’t known by staff.
When would diagnostic cut off be changed?
It could be moved up to eliminate false positives or moved down to eliminate false negatives
What is sensitivity?
This is the % of people who have the disease with a true positive result
What is specifity?
This is the % of people who don’t have the disease who have a true negative. It is the exact opposite of sensitivity.
What is the positive predictive value (PPV)?
This is the % of people with a positive test who have the disease
What is the negative predictive value (NPV)?
This is the % of people with a negative test result who don’t have the diease
What is prevalance?
The % of the population with the disease.
What are some of the contributors to pre-analytical variation?
Time of day Posture fasting status Recent exercise Time in transit to laboratory Temperature during transit Anticoagulant or preservative used Centrifugation time and force
How is analytical variation calculated?
By measuring the internal QC values throughout the day
How is biological variation calculated?
If analytical variation and pre-analytical variation are established, it is possible to calculate biological variation.
