Protein nitrogen unit

From Wikipedia, the free encyclopedia
Jump to: navigation, search

The protein nitrogen unit (PNU) measures the potency of the compounds used in allergy skin tests, and is equivalent to 0.01 microgram (µg) of phosphotungstic acid-precipitable protein nitrogen.[1]

According to Russ Rowlett at the University of North Carolina at Chapel Hill,[2]

Unfortunately, the potency measurements depend on the technique of measurement used, so results of one manufacturer are not comparable to those of another manufacturer. As a result, although PNU's are still used, they are being replaced by bioequivalent allergy units (BAU), which are measured by actual skin testing using reference preparations of standard potency.


  1. ^ May, JC; Sih, JT; Best, J; Douglas, G; Rancour, JM; Renker, HR; Spingola, F; Van Daele, L; Zudeck, S et al. (November 1981). "Protein nitrogen unit precipitation procedure for allergenic extracts: collaborative study". J Assoc off Anal Chem 64 (6): 1435–8. PMID 7309663.  Site is an abstract provided by PubMed
  2. ^ Ross, Rowlett (2002). "P". How Many? A Dictionary of Units of Measurement. University of North Carolina at Chapel Hill. Retrieved 2009-02-05. 

The end product of protein nitrogen in man is Urea