Units and Glucose

[paulroe]

Ok so I'm working with a system that stores glucose measurements and codifies them with LOINC. I am reading from this system and it provides a single LOINC code for glucose measurements. My problem is twofold, I need the units for the value that was stored in the system and I need to know if the value was taken while the person was fasting. The crux of the issue is that the system seems to only store a single LOINC code for this measurement and I can't seem to find any LOINC codes that will tell me both of those pieces of data at once.

These LOINC Codes tell me the test was taken while the person was fasting but do not have a value in the submitted_units column so I don't know the units for the measurement:
6764-5,2353-1,1558-6,1557-8,1556-0,1555-2,1554-5,1550-3,14771-0,14770-2,14769-4,14760-3,14749-6,14743-9,11047-8

This LOINC code tells me the value's unit is mmol/L but does not tell me if the user was fasting or not as well as being very generic from what I can tell:
53553-4

Should they be storing multiple LOINC codes for this measurement? Should I be looking for the data I need elsewhere? Am I totally lost in the woods?

Any help/guidance would be appreciated

[kmercer]

Without knowing what you mean by "system that stores glucose measurements", I cannot give specific advice, but I'll explain the differences between the terms that you listed and you may be able to decide which one you need. If this does not help, please contact us again.

The terms that you have provided have a number of differences that need to be taken into account when deciding the appropriate LOINC code. Submitted units do NOT define a LOINC code - they are displayed for information only. The fully specified name for the codes that you provided is below.

Component - some of the terms probably should not be considered as glucose values. They are flagged below.

Challenges (text to the right of ^) - I'd suggest that for a fasting specimen without knowing the time of the fast that you use "^post CFst"

Property - This is the field that you need to look at when trying to determine how your units are represented.
MCnc means that the units should mg/dL (or similar variant)
SCnc means that the units should be mmol/L (or similar variant)

System -
BldC means that capillary blood was tested
BldV means that whole venous blood was tested
Ser/Plas means that serum or plasma was tested
Urine means that urine was tested

Scale
Qn indicates quantitative
Ord indicates ordinal - results will be 1+, 2+, etc.

Method
Glucometer - test performed by glucometer. This usually is interpreted as a point of care test


LOINC_NUM:COMPONENT PROPERTY TIME SYSTEM SCALE METHOD_TYP
11047-8 Glucose phosphate isomerase CCnc Pt RBC Qn this component has nothing to do with glucose
14743-9 Glucose SCnc Pt BldC Qn Glucometer
14749-6 Glucose SCnc Pt Ser/Plas Qn
14760-3 Glucose^2H post meal SCnc Pt BldC Qn
14769-4 Glucose^pre 12H CFst SCnc Pt Ser/Plas Qn
14770-2 Glucose^post CFst SCnc Pt BldC Qn Glucometer
14771-0 Glucose^post CFst SCnc Pt Ser/Plas Qn
1550-3 Glucose^pre 12H CFst MCnc Pt Ser/Plas Qn
1554-5 Glucose^post 12H CFst MCnc Pt Ser/Plas Qn
1555-2 Glucose^post 12H CFst MCnc Pt Urine Qn
1556-0 Glucose^post CFst MCnc Pt BldC Qn
1557-8 Glucose^post CFst MCnc Pt BldV Qn
1558-6 Glucose^post CFst MCnc Pt Ser/Plas Qn
2353-1 Glucose phosphate isomerase CCnc Pt Ser Qn this component has nothing to do with glucose
6764-5 Glucose^post CFst ACnc Pt Urine Ord Test strip
53553-4 Estimated average glucose SCnc Pt Bld Qn Estimated from glycated hemoglobin This term is NOT a direct measurement of glucose. The value is derived from Hemoglobin A1c

[paulroe]

Thanks Kathy! That answers most all of my questions but it does generate one new one. For the Property values is there a place where those are enumerated or described or is it an industry standard or something that I can look up? I'm going to have to try and resolve the Property value to a Unit type (MCnc => mg/dL) for every data type that I'm collecting so that's why I'm looking for a way to link these two data points.

[paulroe]

Anyone?

[paulroe]

Anyone?

[kmercer]

If you are using RELMA to search for LOINC codes, incorporating the units in the search paramaters will narrow the search to the correct property. I also suggest reviewing section 2.3 of the LOINC User's guide (available at LOINC.org)

[paulroe]

If I have a lab test with a result of 100 and it's LOINC Code is 14770-2 what is the unit type of the measurement? I know based on the property that it's a substance measurement which means it will be a measurement of moles or milliequivalents but in what ratio? The documentation says that Substance denotes that the observation was reported with moles or milliequivalents in the numerator but it doesn't tell me where to find what value to put in the denominator, which is 50% of the information I need.

I'm still trying to resolve a LOINC Code to a Unit type (MCnc => mg/dL) for every data type that I'm collecting. This should be the simplest task that should be documented somewhere obvious and easy to resolve, however I'm on week 3 of this problem. Very simply, without using REMLA take me through how I get from 14770-2 ----> to a unit type like mg/dl OR mmol/L

Frustrated beyond belief.

[paulroe]

After rereading this post and searching further I may be able to add more detail to my question. Earlier on Kathy Mercer said this:

MCnc means that the units should mg/dL (or similar variant)
SCnc means that the units should be mmol/L (or similar variant)

What is meant by the phrase "similar variant"? If a lab test is coded with a LOINC Code that has a property of "SCnc" is that value always going to be in mmol/L units? If it wont always be mmol/L units how do I find out what units the value is in?

[pdbanning]

For your question of what the "similar variants" are:

The Mass Concentration property defines units of measure that are of a metric mass over volume format. Example variants include any portion of a gram over liter, such as ng/dL or mg/L.
The Substance Concentration property defines molar units of measure. Example includes any portion of a mole over liter, such as mmol/L or mole/L.
The LOINC property isn't intended to reverse engineer an exact units of measure back from the LOINC code. Are you not receiving structured HL7 messages, where the units of measure have a defined location?

If I can assist in relieving your frustrations, please contact me directly at pdbanning@mmm.com. We can trade phone numbers.

[paulroe]

Thanks Pam, that helps clarify things for me.