A urine sample shows protein detected by sulfosalicylic acid but negative on dipstick. This pattern most likely indicates presence of which type of protein?

A urine sample shows protein detected by sulfosalicylic acid but negative on dipstick. This pattern most likely indicates presence of which type of protein?

• A. Albumin
• B. Non-albumin protein
• C. Globulin
• D. Casein

Answer: (B)

Dipstick tests mainly detect albumin, while the sulfosalicylic acid (SSA) test precipitates and reveals all proteins in urine. When SSA is positive but the dipstick is negative, it means there are proteins present that are not albumin. That pattern points to non-albumin proteins, such as globulins or light chains (Bence Jones proteins), which dipsticks may miss but SSA will detect. Albumin would be expected to yield a positive dipstick result, so it doesn’t fit this pattern. Casein isn’t a typical urinary protein, whereas non-albumin proteins is the correct, broad category describing this result.

Dipstick tests mainly detect albumin, while the sulfosalicylic acid (SSA) test precipitates and reveals all proteins in urine. When SSA is positive but the dipstick is negative, it means there are proteins present that are not albumin. That pattern points to non-albumin proteins, such as globulins or light chains (Bence Jones proteins), which dipsticks may miss but SSA will detect. Albumin would be expected to yield a positive dipstick result, so it doesn’t fit this pattern. Casein isn’t a typical urinary protein, whereas non-albumin proteins is the correct, broad category describing this result.