This is the single most important early-warning test for kidney damage, especially for anyone with diabetes or high blood pressure. It is a highly sensitive test designed to detect microscopic, invisible amounts of a protein called albumin in your urine. Healthy kidneys keep this protein in, so any "leak," no matter how small, is the first red flag. Early detection is everything. This simple urine test can identify risk years before symptoms appear, giving you the power to protect your kidneys.