A urine microprotein test is a screening test to look for the presence of microproteins in the urine; especially albumin. When the kidneys are healthy, virtually no microproteins pass out of the kidneys and into the urine. However, if a person's kidneys become diseased or damaged, they are less able to leave the microproteins behind, and some microproteins, owing to their small size begin to filter through and appear in the urine. It is necessary to diagnose the presence of microproteins in urine to prevent various kidney related diseases.