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PSA Standardization



Adding Biological Variability into the Mix

Slide 31

October 2009

One further additive issue to the analytical issues deals with biological variability, which should be considered for proper interpretation.  In men over the age of 50 the biological variability from one day to the next is approximately 20%.  This variability holds true across the range of total PSA concentrations of 0.2-20 ng/mL.  Therefore a change of 30%, which accounts for biological and analytical variability, can be considered normal for some men.  Other studies suggest that the baseline PSA actually has to change by 50% to be considered significant.

Biological Variability

 


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