A number of conditions may be associated with proteinuria that is not detected by the urine dipstick test for protein.


Proteins poorly detected by the dipstick method:

(1) immunoglobulins

(2) Bence Jones proteins

(3) hemoglobin

(4) mucoprotein


Conditions masking the level of proteinuria:

(1) dilution (as indicated by a low specific gravity)

(2) pregnancy


If a specimen is diluted, then repeat testing should be done on a less dilute specimen.


If proteinuria is expected clinically but negative on dipstick testing, then consider:

(1) urine protein testing using sulfosalicylic acid

(2) a test for Bence Jones proteins

(3) urine protein electrophoresis and urine immunofixation


Diabetics may secrete an increased amount of albumin that is below the detection limit of a dipstick (microalbuminuria, indicating a micro amount of albuminuria rather than a small form of albumin). This can be measured using a microalbuminuria method.


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