"Proteinuria occurs when the filtration membrane becomes leaky, allowing proteins to cross. This impacts the blood colloid osmotic pressure by the osmolarity gradient between the blood and filtrate, thereby the strength of this pressure."

Proteinuria occurs when the filtration membrane becomes leaky, allowing proteins to cross. This impacts the blood colloid osmotic pressure by decreasing the osmolarity gradient between the blood and filtrate, thereby reducing the strength of this pressure.

Explanation:

Proteinuria is the medical term that describes the presence of proteins in the urine. Proteins, in normal conditions, are not capable of filtrating through the membrane but, in the presence of a disease, this is possible.

Proteins are responsible for the colloid osmotic pressure in the blood vessels, so when proteins get filtered, this pressure decreases and so does the osmolarity gradient between the blood and filtrate. The decrease in osmolarity gradient also produces a decrease of the colloid osmotic pressure because the strength of the pressure is as big as the gradient between the two compartments.