Routine methods for measuring protein in the urine:
(1) dipstick, using tetrabromophenol blue
(2) sulfosalicylic acid
Causes of a false positive urine dipstick test for protein:
(1) urine with alkaline pH (pH > 8)
(2) highly buffered urine
(3) highly concentrated urine
(4) hematuria
(5) quaternary ammonium compounds (antiseptics or detergents)
(6) chlorhexidine (skin cleanser)
(7) unusual urine color
Causes of a false positive urine protein by sulfosalicylic acid testing:
(1) highly concentrated urine
(2) hematuria
(3) radio-opaque contrast agent
(4) antibiotics (sulfonamide, cephalosporin, penicillin)
(5) tolbutamide therapy
(6) pyridium (phenazopyridine)
