Leeuwenhoek had stolen and peeped into the fantastic sub-visible world of little things, creatures that had lived, had bred, had battled, had died, completely hidden from and unknown to all men from the beginning of time. Beasts these were of a kind that ravaged and annihilated whole races of men ten million times larger than they were themselves. Beings these were, more terrible than fire-spitting dragons or hydra-headed monsters. They were silent assassins that murdered babies in warm cradles and kings in sheltered places. It was this invisible, insignificant, but implacable-and sometimes friendly- world Leeuwenhoek had looked into for the first time of all men of all countries. ~Microbe Hunters

Friday, 19 April 2013

QC

I felt the need to write about James O. Westgard because if I didn’t and my biochem prof found out, I would be dead. Westgard rules are the basis for quality control (QC) in the biochemistry/clinical chemistry lab. The founding father of these rules is none other than James O. Westgard himself. What seems like 99% of the work in clinical chemistry involves ensuring accurate and reproducible results. Some tests require the accuracy and precision to be tested with each test run, like ESRs in hematology, but most of chemistry tests require daily calibration using quality control charts, like troponin.

The purpose of quality control is to ensure that our equipment and reagents involved in a test are running in tip top shape to ensure quality health care to the patients. Westgard rules involve using standard deviations (a statistics term) to determine whether or not the test is running accurately and the patient results produced are accurate and can be sent out for diagnosis. You may think, like naïve little me in the beginning, that preforming QC is a waste of time and money and you can spit out more patient results if you just skip that step. However, you would be doing just that: spitting out results. No one would know whether the results are accurate, and it is surprising what can go wrong in the lab. Improper storage of reagents, or expiration and degradation of reagents can greatly affect the results of the patient, so we as a lab, have to preform QC to make sure we are giving you the correct diagnosis. 

I have been looking for the animated picture that my prof put in her PowerPoint for Westgard rules. Here it is, but imaging the animated hearts falling down…


Each lab has to determine their own QC and the "normal" values for their population. In order to do this, they have to test x amount of people to determine the normal distribution. Where do they find these people? In the Emergency room! If you come in with a sore finger, and you get blood drawn on you, it might just be the lab preforming their quality control, and you drew the short stick. It rarely happens that the lab draws from a person who doesn't need blood to be drawn in the first place. Normally, if you have to get tested for something else, for example, iron studies, you might just get another tube drawn for the lab to QC their normal cardiac enzyme results. It is essential we do this. What if the next time you come into the hospital with chest pain and need a cardiac marker test. Well it is a good thing the the lab has up-to-date normal results to efficiently and accurately diagnose you with a heart attack!


Darn good and sure of it,

adot

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