I want to code the following measurements:
Presence of glucose in urine by urine dipstick
values: -, +,++,+++
Presence of nitrite in urine by urine dipstick
values: -, +,++,+++
However, I only find the code 2349-9 with no answer list specified for 1) and the code 5802-4 with example answer list positive/negative for 2).
According to this blog article: Proper use of LOINC question codes with assessment instrument methods - Daniel Vreeman example lists may be extented as needed.
- Could I aplly the values Neg, 1+,2+,3+ from the answer list LL3105-5 (Neg, 1+,2+,3+,4+) to 1)?
- Could I add the values 2+,3+ from the same answer list to 2) to complete the answer list?
Any guidance is much appreciated!
Answer lists are addressed in the LOINC user guide. Knowledge Base – LOINC section 9.2. There are three “types” of answer lists. Here are the 3 types and their definitions:
Example lists are meant to be illustrative of possible result values. Users can also think of them as a starter set to which they may add or subtract depending on their use case. Many of the Example answer lists are in the lab domain, where different labs may report similar results in a variety of ways, such as “Positive”, “Present”, “Detected”, “Abnormal” or “Out of range” but for which we have a single Example answer list.
Preferred lists contain a set of answers that users are strongly encouraged to use. They represent a recommended set, however, in contrast to a Normative list, alternate result values may be used if necessary. Preferred lists may come from a variety of sources, including professional organizations (e.g., American Physical Therapy Association), device manufacturers, and government (e.g., Centers for Diseases Control and Prevention, National Eye Institute).
Normative lists are those specifically defined by a validated instrument or other authoritative source. When using LOINC codes bound to normative answer lists, only answers in the specified set are allowed as result values. Examples of sources for Normative answer lists are PROMIS or the Clinical Pharmacogenetics Implementation Consortium (CPIC).
In your particular case, since the LOINC codes listed in your post either do not have an answer list or have an example answer list, you are within scope to define the answer list for that LOINC code or extend the example answerlist to fit your organizational needs without need to request anything from LOINC.
I hope this helps.
There are several aspects to your question.
Can you share which country(ies) the terms are to be utilized? Some have regulatory aspects for these laboratory result values that will dictate which are utilized. For example in the US, CLIA laboratory regulations require laboratories to follow the In Vitro Diagnostic vendor package insert of FDA 510k approved tests. The package inserts indicate how laboratory tests are to be performed and reported. One vendor may indicate values of “positive” or “negative” , while another vendor for the same test result may have result values of “reactive” or “nonreactive.” Thus the LOINC answers and answer lists may not even match the terms that are required to be used by laboratories.
As such, a downstream user trying to query result values using only the LOINC answer or LOINC list, for these test result values, could miss values that are not on the list. For example, searching by positive or negative above, may miss values for the same test which may be different. Users need to be aware of these aspects.
Many countries also require SNOMED CT qualifier value codes to be used for lab result values such as 1+, 2+, etc from urine dipstick results as you share. The free browser is at SNOMED CT - Home (ihtsdotools.org) I searched for “+++” and found the following: SNOMED International Browser
You’ll see choices such as 3+ out of 4+ or 1+ out of 3+ for response values. You can map the most accurate for your test result values. You may need to contact the laboratory performing the test to get more information about how the test is performed to map it accurately and correctly. Some of the information may be in package inserts and not electronic/ in health IT systems. A number of the SCT codes are listed in addition to the LA codes for LOINC codes.
In one of your previous posts, you ask about answer lists and LOINC answers on them. As John indicated, some of these apply to standardized survey instruments, which includes the questions and answers, so different answers may not be utilized in some of these cases.
If you look closely at 5802-4, it is tied to the dipstick method, which usually is tied to specific types of semi-quantitative or qualitative responses (depending how the test is set up, it can be reported different ways) as you note. However, 2349-9 does not have a specific method listed (is methodless), so several different types of methods may be utilized to report the glucose presence. One may be a tablet based test (see image) while, many urine glucose values are obtained by the test strip method.
If a single lab test result is built in the LIS or EHR or other information for this glucose test result and different methods are used (not a recommended, nor best practice approach), then it would be appropriate to map this methodless LOINC to that result.
thank you so much for your in-depth reply and remarks.
I am mapping terms for a set of German clinical studies. The LOINC terms and answer lists match the laboratory specifications well so far.
You’re right, 2349-9 is methodless but we have defined the dipstick as the standard method. Thank you! Therefore, I will opt for 25428-4 Glucose [Presence] in Urine by Test strip with the answer list of choice from LL3105-5.
A follow up question regarding number 5: We also want to map the following term:
Presence of erythrocytes in urine by urine dipstick
values: -, +,++,+++
In Loinc, there are only terms associated with other measurement methods (Light microscopy, Automated, Computer assisted…) and a general, methodless one (33051-4 Erythrocytes [Presence] in Urine). Would this be another case where it is appropriate to use the more general code?