12 replies to this topic

[ujla80]

hi all

can anybody tell me the amount of proteins excreted  in urine of normal beings? is lowry a good method for detecting urinary proteins?
help me please....  

[HomeBrew]

Accoring to here, the normal range of total protein on urinalysis is 6.3-8.2 gm/dL.  But, according to here, the normal value is "negative".  I suppose it depends on the sensitivity of the assay used.

BTW, 63 - 82 g/L seems pretty high to me...

[hobglobin]

HomeBrew, on Jul 5 2009, 10:44 PM, said:

Accoring to here, the normal range of total protein on urinalysis is 6.3-8.2 gm/dL.  But, according to here, the normal value is "negative".  I suppose it depends on the sensitivity of the assay used.

But the in first link also gives negative-trace Protein in Urinalysis...I guess normally a test strip (showing different intensity of lilac staining) is used for routine analysis...don't know how sensitive this method is.
But after stress such as sports etc. the protein concentration is raised at least temporarily.

[ujla80]

thanx

i am looking for proteinuria in mice urine samples. with lowry i get very high protein levels 160mg/dl-3000mg/dl in controls(normal healthy mice)...whereas when i do strip test i get lower amounts i.e trace-100mg/dl....what could be the reason of such high values with lowry?

[Gerard]

Is it possible your using a teststrip that only detects albumin?

[mdfenko]

you are probably above the useful range of the lowry assay.

clinical labs use the biuret protein assay. it is useful for greater amounts of protein than lowry.

[ujla80]

the test strip is more sensitive to albumin than other proteins...

m going to use biurett method and see the results.

[DRT]

Wouldn’t the ammonium/urea type compounds in urine cause problems for both the Biuret and Lowry assays or are the concentrations too low to worry about?
Is it possible that the pH was different between the standards and samples for the Lowry assay?

[mdfenko]

DRT, on Jul 6 2009, 11:21 PM, said:

Wouldn't the ammonium/urea type compounds in urine cause problems for both the Biuret and Lowry assays or are the concentrations too low to worry about?
Is it possible that the pH was different between the standards and samples for the Lowry assay?

urea won't significantly affect the assay. biuret has a peptide-like bond which is detected by the assay, urea doesn't (although, there may be some biuret in the urea and that will be detected).

the pH of the samples won't have a significant effect on the lowry (or biuret). the reagent has enough naoh to maintain a basic environment.

[sgt4boston]

Are you looking for particular proteins?  Gammopathies?

[chdd]

i had used Bradford method(Coomassie brilliant blue G-250)  to assay proteins in urine，it seems good.

[ujla80]

no not specific proteins. i am just looking for proteinuria...

sgt4boston, on Aug 17 2009, 11:27 AM, said:

Are you looking for particular proteins?  Gammopathies?

[ujla80]

hi

did u dilute the urine sample if yes then how much dilution?

chdd, on Aug 20 2009, 12:26 PM, said:

i had used Bradford method(Coomassie brilliant blue G-250)  to assay proteins in urine，it seems good.