Option 1: Blood proteins are not normally found in urine. When there is damage to the glomeruli (the filtering units in the kidneys), blood proteins can leak into the urine. This condition is known as proteinuria.

Option 2: Creatinine is normally found in urine. It is a waste product that is produced when creatine in the muscles breaks down. The level of creatinine in the urine can be measured to estimate kidney function.

Option 3: Red blood cells are not normally found in urine. The presence of red blood cells in urine may indicate various conditions such as urinary tract infections, kidney stones, or kidney disease.

Option 4: White blood cells are not normally found in urine. Their presence in urine may indicate an infection or inflammation in the urinary tract.

Alert - Correct answer should be 2. Creatinine is the correct substance that is normally found in urine.