ug/spec vs. ug/TV

Hi there,

I have a question regarding the units of measure for timed urines. Is there any difference between ug/specimen and ug/TV?


Susan Korsak

How are you, Susan?

First thought when seeing just the subject line was inferring content {weight} from ug/specimen vs. volumes from ug/TV.

I usually see the unit of ug/specimen in solid form specimens, such as nail clippings, hair, feces, etc. This would be a mass content property

Then I see your sentence, you’re only dealing with timed urines. Liquids. Volume now makes more sense. In your opinion, are they referring to the collection duration as the “specimen”? Please look and see if they’re testing an aliquot as ug/dL in one field, and a calculated ug/total volume by collection duration in a second field before using the mass ratio property. There are different LOINC codes by the timing attribute to keep the 2, 4, 10, 12, 24 hr timings of urine separate.

16518-3 Calcium:MRat:2H:Urine:Qn:

27091-8 Calcium:MRat:4H:Urine:Qn:

18186-7 Calcium:MRat:12H:Urine:Qn:

6874-2 Calcium:MRat:24H:Urine:Qn:

Each of the above could use a measurement of ug/TV, in my opinion.

The specimens are 24 hour urines that are reported with a single value.

To summarize, my question is this:

For 24 hour urines, is there a clinically significant difference between the reporting units listed below that require they be listed separately in a user interface for the purposes of result graphing or trending?




  • Sue