Test Catalog


What is LOINC and Why Does it Matter?

November 2012


The recent decision by the Supreme Court of the United States to uphold the Patient Protection and Affordable Care Act ensures that implementation of this and other associated health care programs will be completed in the next few years. It therefore behooves health care providers to become familiar with these plans so they can take advantage of the incentives offered and avoid penalties for noncompliance.

Image of a person working on computer

One idea implicit in the health care initiatives is that health information technology can improve efficiency and help reduce costs. Implementation of the electronic health record (EHR) with the ability to efficiently retrieve and share information across health care providers is the key element in the “meaningful use” initiative.

More specifically, under the terms of the Health Information Technology (HITECH) Act, the Centers for Medicare & Medicaid Services (CMS) will provide incentive payments to health care providers who adopt certified electronic health record technology and use it to demonstrate meaningful use of that technology. The CMS incentive program will be implemented in several stages or phases. The proposed stage 2 criteria for meaningful use focus on the electronic capturing of health information (including laboratory test information) in a structured format. It seems certain now that the structured format for laboratory tests will involve the use of LOINC (Logical Observation Identifiers Names and Codes). Although somewhat redundant, the terminology convention “LOINC codes” will be used in this discussion.

What is LOINC?

LOINC codes are a set of universal codes and names to identify laboratory and other clinical observations that facilitate exchange and pooling of results for clinical quality measures, outcomes management and research. LOINC was initiated by Regenstrief Institute research scientists who continue to develop it with the collaboration of the LOINC committee. Regenstrief Institute, Incorporated is an internationally recognized informatics and health care research organization that is dedicated to the improvement of health through research that enhances the quality and cost-effectiveness of health care. Established in 1969 by philanthropist Sam Regenstrief on the campus of the Indiana University School of Medicine in Indianapolis, the Institute is supported by the Regenstrief Foundation and is closely affiliated with the Indiana University School of Medicine and the Health and Hospital Corporation of Marion County, Indiana.

Use of LOINC codes will foster the development and use of suitable standardized diagnostic test and procedure terminologies to support the safe, accurate, and effective exchange of health information. Moreover, this will facilitate the evaluation of the utility and cost-effectiveness of test usage across the spectrum of health care providers. With appropriate implementation, there will be one specific LOINC code for the same specific assay performed in any laboratory in any country that has adopted the system. The key here is specificity, so that examiners can be assured that they can survey the use of the same test across many health care providers by applying the specific LOINC code.

Adoption of LOINC codes by health care providers requires the “mapping” of their own institutional test codes to the LOINC codes for that same test. A mapping tool, Regenstrief LOINC Mapping Assistant or RELMA, is available on the Regenstrief Web site and the Institute also sponsors on-site training twice a year on the use of RELMA. Commercial services are available that will perform the mapping, maintain the database, and submit requests for LOINC codes for newly developed tests. Mayo Clinic in Rochester, Minnesota has contracted with the Information Technology Section of 3M for this service.

Why Use LOINC?

LOINC and Reportable Disease Reporting

Currently, health care providers are required to use LOINC codes when reportable disease results are sent to state and federal public health laboratories. The Centers for Disease Control and Prevention (CDC) has developed a LOINC panel specifically for public health case reporting called the Reportable Condition Mapping Tool (RCMT). This panel should be of considerable assistance to health care providers in identifying the correct LOINC code for their reports. Laboratories are also required to archive LOINC codes for test results they receive from other laboratories to which they have referred specimens and, similarly, referral laboratories should provide their clients with LOINC codes when sending results. Mayo Medical Laboratories provides an Excel spreadsheet that includes all available LOINC codes for assays performed at Mayo Medical Laboratories. An excerpt from the spreadsheet is shown in the Table.

DOXP Nordoxepin 3862-0 Nordoxepin:MCnc:Pt:Ser/Plas:Qn:
DOXP Doxepin and Nordoxepin 3582-4 Doxepin+Nordoxepin:MCnc:Pt:Ser/Plas:Qn:
HALO Haloperidol, S 3669-9 Haloperidol:MCnc:Pt:Ser/Plas:Qn:
MPSS Albumin 2862-1 Albumin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSS Alpha-1 Globulin 2865-4 Alpha 1 globulin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSS Alpha-2 Globulin 2868-8 Alpha 2 globulin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSS Beta-Globulin 2871-2 Beta globulin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSS Gamma-Globulin 2874-6 Gamma globulin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSS A/G Ratio 44429-9 Albumin/Globulin:MCrto:Pt:Ser/Plas:Qn:Electrophoresis
MPSS Impression 12851-2 Protein pattern:Imp:Pt:Ser/Plas:Nom:Electrophoresis
MPSS M spike 33358-3 Protein.monoclonal:MCnc:Pt:Ser/Plas:Qn:Electrophoresis
MPSU A/G Ratio 44293-9 Albumin/Globulin:MCrto:Pt:Urine:Qn:Electrophoresis

Table. Examples of LOINC Code Assignment

A fully specified name of a test result or clinical observation has 5 to 6 main parts including: 1) the name of the component or analyte measured, 2) its property (substance concentration, mass, volume), 3) the timing of the measurement, 4) the type of sample (serum, urine, etc), 5) the scale of measurement (qualitative versus quantitative, etc), and 6) the method (RIA, Immune Blot, etc). The method is only included if the interpretation will be affected and is only listed at a generic level; most often, the LOINC name will not include the method.

LOINC and Laboratory Test Result Reporting

Mayo Clinic information technology personnel are developing programs that will enable LOINC codes to be entered into the test result stream of the laboratory information system (LIS) and be included in the report that appears in the electronic health record. Similarly, programs in development will allow LOINC codes to be directly included in the result reports provided to Mayo Medical Laboratories clients. Of course, challenges will still exist in reconciling the electronic reports provided by Mayo Medical Laboratories with each client’s LIS.

Some uncertainties remain about the exact timelines for the required implementation of LOINC codes as the structured format for laboratory results. However, Mayo Medical Laboratories will continue to develop programs to provide that information to clients as efficiently as possible.

Alpha 1 globulin:MCnc:Pt:Ser/Plas:Qn:Electrophoresis

LOINC and Accountable Care Organizations

The establishment of Accountable Care Organizations (ACOs) is an additional incentive program intended to improve care while reducing costs. ACOs are groups of health care providers that voluntarily unite to provide coordinated care to their patients while avoiding unnecessary duplication of services and preventing medical errors. 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. Electronic health records with health information exchange capabilities will be needed to achieve success. An ACO that succeeds in delivering high-quality care and controlling costs will share in the savings achieved for the Medicare program.


The Centers for Medicare & Medicaid Services has established incentive programs for payments to health care providers who demonstrate meaningful use of the electronic health record technology, with a key element being the efficient retrieval and sharing of information across health care providers. The stage 1 and stage 2 criteria for meaningful use require the electronic capture of health information in a structured format and LOINC is the proposed structured format for the laboratory test component. The use of LOINC enables the exchange and examination of test data from health care providers for use in clinical care and research.

Authored by: Jon Rosenblatt, MD


  1. Centers for Medicare & Medicaid Services. Available at http://www.cms.gov/ Accessed 9.13.2012
  2. Regenstrief Institute, Inc. Available at: http://www.regenstrief.org/ Accessed 9.13.2012
  3. Regenstrief Institute, Inc. LOINC. Available at: http://loinc.org/ Accessed 9.13.2012
  4. RCMT-Reportable Condition Mapping Table Workgroup. Available at: http://www.phconnect.org/group/rcmt Accessed 9.13.2012

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