In order to communicate clinical laboratory results to clinicians (and patients) with reduced risk of misunderstanding, the laboratory reports need to be:

• Unambigous.   
• Structured 
• Well-defined

The same measurement unit can be expressed in various ways, e.g. ng/mL and µg/L. These may be seen as two different measurement units by clinicians whom may misunderstand laboratory results that are using several expressions of a measurement unit interchangeably. In worse case, the misunderstanding would lead to mistreatment.

International Union of Pure Applied Chemistry (IUPAC) and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) own the NPU terminology

The Commitee of Nomenclature on Properties and Units (C-NPU) is responsible of maintaining and developing the NPU terminology. The commitee consists of 5 titular IFCC members, elective and corresponding members and one IUPAC representative.

The NPU terminology consists of more than 25,000 NPU codes that are in a NPU database. The database can be accessed via IFCC’s NPU database or the Danish homepage (in Danish).

The International Office of Release Center of NPU Terminology is responsible of the maintenance of the NPU database.