Happy LOINCing with HDD Access!

September 9, 2015 / By Senthil Nachimuthu, MD, PhD

The July release of HDD Access, the open public version of the 3M Healthcare Data Dictionary, included LOINC® (version 2.50), the standard terminology for lab and clinical observations. We thank Regenstrief Institute for their active support in making this possible. LOINC was perhaps the most-requested terminology on the HDD Access discussion forums, and we hope that this release helps our users to take another big step towards clinical data interoperability. We noticed an increase in downloads after we released LOINC, many of them by new users. So, for those who are just starting out, here’s a brief overview of how to use the LOINC content within HDD Access.

As you may know, HDD Access is a terminology server that enables interoperability between various standard terminologies, as well as between standard terminologies and your local terminologies. Though there are several ways to implement LOINC and other standard terminologies, HDD Access makes it a lot easier. In addition to implementing the included standard terminologies, HDD Access allows users to create their own local extensions in their installation of HDD Access, and allows them to load their local terminologies into it. The first step is to download and install the latest release of HDD Access. Once you install HDD Access, you can log on to the web control panel of their local installation, go to content management, and click “Request Local Extension.” In a minute, the user’s local installation of HDD Access will be provisioned with a local extension, with its own unique range of identifiers.

The first step after you obtain a local extension is to create your own local terminology (also known as vocabulary or code system). At a minimum, you will need a name for your code system (e.g. Acme Hospital Lab Terminology), and two contexts – a display context (e.g. Acme Lab Description Context) which denotes the human readable names, and an interface context (e.g. Acme Lab Code Context) which denotes the machine readable codes. In addition, you will also need to assign an Object Identifier, or OID, for your terminology. If you have an OID for your terminology registered with a registry such as HL7, you may enter it here. If not, accept the default OID that is assigned under 3M’s OID root. The OID is the unique identifier for your terminology itself, and you will use it in your API calls and client applications. The OID is a sequence of digits separated by several periods. For example, the OID for LOINC is 2.16.840.1.113883.6.1 and it is registered with and assigned by the HL7 OID registry.

Now, if you want to make your local lab or clinical orders and observations interoperable with LOINC, you need to map your lab terminology to LOINC content within HDD Access either through the front-end, or by writing your own client applications against our API. The API and front-end software’s documentation, as well as the video tutorial should come in handy when you try to add your own local content to your copy of HDD Access. In case of lab orders and observables, mapping is typically done between equivalent concepts. In HDD Access, we do this by a mechanism that we call “implicit mapping.” Keep in mind that when you map your local term to a LOINC term, you are in effect mapping your local term to an HDD concept to which the LOINC term is mapped. This is due to the centralized mapping design used by the HDD, which reduces the number of map sets required for interoperability (which is a topic by itself that I’ll explain it in a future blog post).

Top 50 LOINC Submitters, LOINC v2.50 (Dec 2014)


While mapping your local terminology to the LOINC content within the HDD, you might find that there may not be an equivalent LOINC term for your local terminology concept. This is normal and is well known among clinical terminologists. Our experts report in AMIA Proceedings that “the proportion of commercial laboratory result master files with a LOINC code ranged from 51.1% to 74.0%. The average is 63.4%.” If there isn’t an equivalent LOINC term, you can still map your local term to an equivalent HDD concept if one exists (and we will map new LOINC terms to such HDD concepts when they are added by LOINC), or to a new local concept that you create in your local extension if a match doesn’t exist. You can submit such new terms to LOINC by following their submission process. In fact, our subject matter experts have a streamlined process for submitting new term requests to LOINC that we receive from customers of our professional solutions. We take pride in mapping hundreds of thousands of concepts/terms to LOINC for numerous hospitals, laboratories and other healthcare organizations for about two decades, and we have been the largest submitter of new terms to LOINC, as you can see from the chart below (reference: SOURCE column of the LOINC release table – note that we are listed under six different names as 3M and various ‘3M_CustomerProjects’).

I was naturally curious if the inclusion of LOINC in HDD Access will get an increased interest in downloading the content from the HDD Access user community. As I expected, the number of downloads in the first 30 days more than doubled compared to the previous release. Most of the increase has been in the Windows Installer and the Full XML Content v34 packages, showing that most of the new downloaders are installing the software on their Windows machines, and are loading the core content, which includes LOINC, into their Windows installations. I am crunching more numbers to find informative trends, and it will be the subject of another blog post in the future.

Please feel free to reach out to us through the discussion forums. As always, we actively watch these forums for questions from our users, and we will answer your questions as soon as we can. You are also welcome to answer other users’ questions – thanks to those of you who do that already.  As they say in the LOINC world, Happy LOINCing!

Senthil K. Nachimuthu, MD, PhD,  Medical Informaticist with 3M Health Information Systems’ Healthcare Data Dictionary (HDD) team.

Need more than HDD Access? Check out our professional solutions.