What substance increases in the urine during glomerular disease?

• A. Glucose
• B. Protein
• C. Ketones
• D. Bilirubin

Answer: (B)

When the glomerular filtration barrier is damaged, its ability to retain large substances like proteins is reduced. Plasma proteins, especially albumin, begin to leak into the urine, causing proteinuria. This leakage is a hallmark of glomerular disease because, under normal conditions, proteins are largely kept out of the urine by the filter’s size and charge selectivity. The other substances listed don’t rise specifically because of glomerular injury: glucose appears in urine mainly when blood glucose is high enough to exceed the renal threshold; ketones appear with fat metabolism changes or insulin deficiency; bilirubin in urine points to liver or biliary problems. Therefore, protein in the urine best reflects glomerular pathology.