Hot Topic

What is LOINC and Why Does it Matter?


Receive notification when new Hot Topics are published:

Click CC to turn on closed captioning.

Published: November 2012

Print Record of Viewing

LOINC (Logical Observation Identifier Names and Codes) is a universal code system for identifying laboratory tests and clinical observations. Mapping local terms to LOINC enables the exchange and aggregation of electronic health data from many independent systems, including clinical care, research, and outcomes management. Dr. Rosenblatt describes how LOINC assignments are made and the importance of these codes in laboratory medicine and clinical care.

Presenter: Jon Rosenblatt, MD

Questions and Feedback

Contact us:


Download the PDF

I have nothing to disclose.

The United States Supreme Court decision upholding the Affordable Care Act has heightened interest in government programs to improve access to health care while increasing efficiency and reducing costs. An important element of these efforts is the adoption and efficient use of electronic health records or EHRs.

The Centers for Medicare & Medicaid Services otherwise known as CMS, has established EHR incentive programs under the Health Information Technology or HITECH act of 2009. The programs provide for payments to health care providers who demonstrate “meaningful use” of the EHR technology.

Use of electronic health records to efficiently retrieve and share information across health care providers is a key element in the “meaningful use” initiative. The existing stage 1 and proposed stage 2 criteria for “meaningful use” focus on the electronic capturing of health information in a “structured format” which for laboratory tests will involve the use of LOINC.

The definition of “structured data” as outlined in the Code of Federal Regulations indicates that the test report must contain the following: positive patient identification; name and address of the laboratory; test report date; test performed; specimen source; test result; and if applicable, units of measurement and any information on unacceptable specimens.

So what is LOINC? LOINC is an acronym for Logical Observation Identifier Names and Codes. LOINC is a universal code system for identifying laboratory tests and some clinical observations. Mapping local terms to LOINC enables the exchange and aggregation of electronic health data from many independent systems for purposes of clinical care, research, and outcomes management.

In 1999, LOINC was identified by the HL7 standards development organization as a preferred code set for laboratory test names in transactions between health care facilities, laboratories, laboratory testing devices, and public health authorities. LOINC is a universal identifier used in HL7 messaging embedded alongside the local laboratory’s mnemonic, display name, units of measure, reference range, and interpretive data. However, it should be noted that LOINC should not carry the full burden of identification for every aspect of the laboratory test.

The Regenstrief Institute is the overall steward of LOINC and Web addresses are provided here. Regenstrief is located at and affiliated with the Indiana University School of Medicine in Indianapolis and is supported by the Regenstrief Foundation.

RELMA, an acronym for Regenstrief LOINC Mapping Assistant, is a computer application for mapping local test codes to universal LOINC assignments. A Web-based version of RELMA is available at the indicated website. The Institute conducts RELMA workshops twice a year in Indianapolis and information is available on the Web site.

LOINC assignment is based on the component or analyte, specimen type, specimen collection method and duration, units of measure, assay method, and result format.  

Currently, health care providers are required to use LOINC assignments with reportable disease result reports to state and federal public health laboratories. The Centers for Disease Control or CDC has developed a LOINC panel specifically for public health case reporting. It is termed the Reportable Condition Mapping Tool or RCMT and a Web address is provided here.  

Laboratories are also required to archive LOINC codes for test results received from laboratories to which they have referred specimens. In addition, the referral laboratories themselves should provide clients with LOINC codes when sending them their results. Mayo Medical Laboratories’ assigned codes are available on an Excel spreadsheet located on the Web site which is identified as the LOINC code list.  

This is an example of the Excel spreadsheet found at the MML website which contains the LOINC assignments. In the column labeled RES CODE are the Mayo codes for each specific analysis. The corresponding LOINC codes and assay attributes are seen in the 2 right-hand columns.

 For phase 2 of “meaningful use”, the laboratory results objective will be a “core” objective; that is it will be required rather than optional. The phase 2 time line includes publication of the final rules in August of this year and implementation early in 2013, although CMS may elect to delay the effective date beyond January 1st.  

At Mayo we plan to associate LOINC with our laboratory information system (which is SOFT) as well as interface LOINC codes with electronic ordering and lab results in the electronic health record. We also plan to interface LOINC coded referral lab results with the Mayo Clinic patient and MML client test results stream. 

LOINC will be an important consideration for newly established Accountable Care Organizations or ACOs. ACOs are groups of health care providers who come together voluntarily to give coordinated care to their Medicare patients. The goal of coordinated care is to ensure that patients get the right care while avoiding unnecessary duplication of services and preventing medical errors.

An ACO which succeeds in delivering high-quality care and controlling costs will share in the savings achieved for the Medicare program. An ACO must share data, manage costs and quality, avoid unnecessary services, and measure the results. Electronic health records with health information exchange capabilities will be needed to achieve these goals. 

The formation of ACOs will necessitate the efficient exchange of test result information among health care providers with different laboratory information systems. Use of LOINC assignment by the various institutions within a newly formed ACO should facilitate that task. 

So, in summary, LOINC will be the “structured format” for the laboratory test component of the “meaningful use” of the electronic health record in the incentive payments program established by CMS. The RELMA application enables mapping of local test codes to this universal code system, LOINC. Use of LOINC enables the exchange and examination of test data from different health care providers, as well as those within an ACO, for use in clinical care and research. Thank you.