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PSA Standardization



WHO 96/670 Total PSA Preparations16

Slide 22

October 2009

Interestingly, Dr. Klee at Mayo also evaluated the effect of matrix bias back in 2004 and showed that how or what the WHO standard is diluted with has an effect on the PSA results from different assays.  In that study, the WHO material was diluted into six different matrices, including PBS buffer with bovine serum albumin, 2 and 5% human serum albumin, manufacturer specific diluents and a synthetic matrix consisting of BSA, BGG (bovine gamma globulin), gelatin, and mannitol in PBS.

The graph on the left shows the total PSA standard at 4 ng/mL, and the graph on the right similar data but at 10 ng/mL.  Both graphs show the Access (which used the Hybritech calibrator) giving results that are higher than the Centaur (which used a WHO standard).  Variations in the standardization procedure for diluting the WHO standard, which is conducted by manufacturers, may account for some of the differences noted between assays that are traceable back to the same standard.

Total PSA Preparations

 


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