Electronic Exchange of Clinical Laboratory Information: Issues and Opportunities. UNIFIED CODES FOR UNITS OF MEASURE (UCUM)


The UCUM is a code system intended to include all units of measures contemporarily used in international science, engineering, and business. UCUM facilitates unambiguous electronic communication of quantities together with their units, and the focus of UCUM is electronic as opposed to human communication. UCUM, though heavily based on existing standards for units of measure which include ISO 2955‐1983 and ANSI X3.50‐1986, is recognized by standards experts as being more stable in content and free of ambiguities. Additionally, it assigns a concise semantic to each defined unit. Today, typically the units of measure for lab results are represented in text and not in UCUM. For example, the result for a platelet count is represented as PerMicroLiter (non‐UCUM) instead of the valid UCUM code of μL.36 Representing the units of measure for lab results as text does not support system interoperability; this is one of the major drivers for UCUM. Most respondents agreed that having a standard for the unit of measure could be beneficial, though there are significant issues with respect to securing broad adoption of such a standard.

Laboratory discussants indicated that, in the current lab exchange workflow, the instrument device or intermediary would need to generate the UCUM. Discussants indicated that currently device manufacturers are not required to use UCUM. Instead, the device manufacturers generally use proprietary codes. In order to move to UCUM, these proprietary codes will need to be mapped to UCUM. For the reasons identified above, the lab industry is currently not using UCUM internally and will therefore not be able to send this information out as part of the HL7 message to receiving systems like EHRs.
Discussants noted that HITSP’s focus on the use of UCUM is somewhat problematic given the limited support and market penetration of this standard. Additionally, since units of measure is a CLIA required data element that must be displayed, in a human readable format, to the end user, laboratories are sensitive to validation issues that can arise when EHR vendors receive and display UCUM. It was noted that it often takes a long time for standards to be adopted.

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