Logical Observation Identifiers Names and Codes (LOINC®)



Logical Observation Identifiers Names and Codes (LOINC) is a database and universal standard for identifying not only laboratory observations but also clinical test results. It was developed and is maintained by the Regenstrief Institute of Health Care, an international non-profit medical research organization, in 1994. Originally called Laboratory Observations, Identifiers, Names and Codes (LOINC), however, the system is being extended to include nonlaboratory observations (such as electrocardiograms, vital signs, and so on), so Logical has replaced Laboratory to reflect the change. LOINC was created in response to the demand for an electronic database for clinical care and management and is publicly available at no cost.
It is endorsed by the American Clinical Laboratory Association and the College of American Pathologist. Since its inception, the database has expanded to include not just medical and laboratory code names, but also: nursing diagnosis, nursing interventions, outcomes classification, and patient care data set.
LOINC applies universal code names and identifiers to medical terminology related to the Electronic Health Record. The purpose is to assist in the electronic exchange and gathering of clinical results (such as laboratory tests, clinical observations, outcomes management and research).


Why Using LOINC

Currently, many laboratories are using ASTM 1238 or its sister standard, HL7, to send laboratory results electronically from producer laboratories to clinical care systems in hospitals. Most laboratories identify tests in these messages by means of their internal (and idiosyncratic) code values. Receiving medical informatics systems cannot fully "understand" the results they receive unless they either adopt the producer's laboratory codes (which is impossible if they receive results from multiple source laboratories, e.g.; the hospital lab, the local commercial lab, and a nursing home lab), or invest in the work to map each laboratory's code system to their internal code system.
If medical information producers who wish to communicate with each other used the LOINC codes to identify their results in data transmissions, this problem would disappear. The receiving system with LOINC codes in its master vocabulary file would be able to understand and properly file HL7 results messages that identified clinical observations via LOINC codes. Similarly, if test and observation codes were reported test with the LOINC codes, government agencies would be able to pool results for tests from many sites for research management and public health purpose.
The LOINC codes (and names) for test observations should be of interest to hospitals, clinical laboratories, doctors' offices, state health departments, governmental health care providers, third-party payers, and organizations responsible for quality assurance and utilization review.


How LOINC Works

The LOINC codes are not intended to transmit all possible information about a test or observation. They are only intended to identify the test result or clinical observation. Other fields in the message can transmit the identity of the source laboratory and special details about the sample. (For instance, the result code may identify a blood culture, but the message source code can be more specific and identify the sample as pump blood.) The level of detail in the LOINC definitions was intended to distinguish tests that are usually distinguished as separate test results within the master file of existing laboratory systems. Indeed, at the outset, they used the master files from seven U.S. laboratories to shape this effort, and requests from commercial labs and hospitals continue to shape the content of the LOINC effort.

Each LOINC record corresponds to a single test result or panel. The record includes fields for specifying:
  1. Component (analyte) - e.g. potassium, hemoglobin, hepatitis C antigen.
  2. Property measured - e.g. a mass concentration, enzyme activity (catalytic rate).
  3. Timing - i.e. whether the measurement is an observation at a moment of time, or an observation integrated over an extended duration of time - e.g. 24-hour urine.
  4. The type of sample - e.g. urine; blood.
  5. The type of scale - e.g. whether the measurement is quantitative (a true measurement) ordinal (a ranked set of options), nominal (e.g. E. coli; Staphylococcus aureus), or narrative (e.g. dictation results from xrays).
  6. Where relevant, the method used to produce the result or other observation.
A formal, distinct, and unique 6-part name is given to each term for test or observation identity. The database currently has over 41,000 observation terms that can be accessed and understood universally.
It also contains information about the amount, route, and timing of physiologic or pharmacologic challenges (e.g. oral glucose tolerance test, which would be expressed in LOINC as GLUCOSE^1H POST 100 G GLUCOSE PO1). Further examples can be found in our textbook (Medical Informatics, p.236), Figure 6.10 - that shows some typical fully specified names for common laboratory tests.
The LOINC identifiers do not usually include the method in the name for chemistry tests, where tests are more often standardized to normalized methods; they do include methods for most serological tests and coagulation studies. This same principle is usually reflected in the master files of existing laboratories. Of course, the method can always be reported as a separate item of information in a result message regardless of whether it is part of the test name. In the United States, PO (an abbreviation for per ora ) is used to identify medications taken by mouth.

Some additional advantages resulting from adopting LOINC may include improved communication in integrated healthcare delivery networks, improved community wide electronic health records, the automatic transfer to public health authorities of case reports for reportable diseases (e.g. for disease control or detection of epidemics), improved transfer of payment information for services rendered and a significant improvement in the overall quality of health care by reducing errors in the system.
The fact that universal standards are being promoted (if not adopted by national organizations and agencies) is an indication that the dialogue will continue regarding the development, structure, financing, monitoring, enforcement, and integration of standards within the broader health care system.


References

  1. LOINC - Wikipedia, the free encyclopedia
  2. Regenstrief Institute
  3. Health Informatics: A Modern LOINC
  4. For vendors, LOINC a fast track to the future
  5. Open Clinical - LOINC
  6. LOINC, a Universal Standard for Identifying Laboratory Observations: A 5-Year Update
  7. Update on Logical Observation Identifier Names and Codes (LOINC)
  8. Wiederhold, G., Shortliffe, E.H., Fagan, L.M., Perreault L.E. Medical Informatics: Computer Applications in Health Care and Biomedicine. New York: Springer, 2001.