The<unk>  (PNU) measures the potency of the compounds used in allergy skin tests, and is equivalent to 0.01 microgram (µg) of phosphotungstic acid-precipitable<unk><unk> . Potency measurements depend on the measurement technique, so that results from different manufacturers cannot be reliably compared: as a result, PNUs are being replaced by bioequivalent allergy<unk> s (BAU), which are measured by skin testing using reference preparations of standard potency.
Protein nitrogen unit
Oxygen equivalent
Electricity
CO2 content
Anion gap
Milligram per cent
Hydrogen water
Bioactive compound