High retinol-binding protein suggests early proximal tubular injury. Retinol-binding protein is filtered out of the glomerulus and is almost entirely reabsorbed by the epithelial cells of the proximal tubule, with only a small amount excreted in the urine. Under normal conditions, very little is excreted in the urine. When the proximal tubules of patients with chronic nephritis have damage, blood β2-microglobulin as well as endogenous creatinine clearance is still within the normal range, and then there is a significant increase in the excretion of urinary retinol-binding protein. Many patients with IgA nephropathy have significantly higher retinol-binding protein excretion, so increased urinary excretion of retinol-binding protein can be used as a marker for early renal proximal tubular injury. If you have high retinol-binding protein, you need to check it out in time and treat it actively.