A urine specimen that exhibits white foam on being shaken should be suspected of having an increased concentration of

A urine specimen that exhibits white foam on being shaken should be suspected of having an increased concentration of

• A. Protein
• B. Hemoglobin
• C. Bilirubin
• D. Nitrite

Answer: (A)

White, persistent foam when urine is shaken points to protein in the sample. Proteins act as surfactants, lowering surface tension and stabilizing air bubbles, so bubbles form and last longer. Normal urine has little protein, so any foam tends to vanish quickly. This makes proteinuria the most likely explanation for white foam. Hemoglobinuria can redden urine and isn’t known for causing persistent foam; bilirubinuria affects color but doesn’t reliably produce foam; nitrites reflect bacteria and don’t cause this foaming pattern.

White, persistent foam when urine is shaken points to protein in the sample. Proteins act as surfactants, lowering surface tension and stabilizing air bubbles, so bubbles form and last longer. Normal urine has little protein, so any foam tends to vanish quickly. This makes proteinuria the most likely explanation for white foam. Hemoglobinuria can redden urine and isn’t known for causing persistent foam; bilirubinuria affects color but doesn’t reliably produce foam; nitrites reflect bacteria and don’t cause this foaming pattern.