Abstract:

Objective To evaluate the commonly-used methods for quantitative determination of urinary protein,and to analyze the influencing factors of false positivity in the determination of urinary protein by dry chemical method. Methods A total of 2 500 cases of random urine specimens were collected,and urinary protein was determined by dry chemical method and sulfosalicylic acid precipitation test. For those specimens with different results from the 2 methods,quantitative determination was performed using Modular P800 automatic biochemical analyzer,focusing on the main influencing factors. Aiming at the main influencing factors of occult blood and urinary pH design simulation experiments,the reason of false negativity or false positivity in dry chemical method was evaluated. Results Totally,2 500 random urine specimens were determined by dry chemical method and sulfosalicylic acid precipitation test. The results of 2 391（95.64%） specimens were identical,including one-level difference,while the results of 109（4.36%） were not identical. There was statistical significance between dry chemical method and sulfosalicylic acid precipitation test（P<0.05）. Red blood cell ≥1×10⁵ in urine specimens would cause false positivity. Urinary pH 7.0-8.5 would cause false positivity,while urinary pH ≥8.5 would cause false negativity. Conclusions Red blood cell in urine and urinary pH would cause false positivity and false negativity in dry chemical method. Clinical laboratories should pay enough concern and attention.

Key words: Urine protein, Dry chemical method, Sulfosalicylic acid precipitation method, False positivity, False negativity