Elevated β2-microglobulin often requires a combination of blood β2-microglobulin and urine β2-microglobulin test results, which are analyzed simultaneously. According to the renal excretion process of β2-microglobulin, increased urinary β2-microglobulin more sensitively reflects impaired proximal tubular reabsorption, such as interstitial tubular disease, early tubular injury caused by drugs or toxic substances, and early acute rejection after renal transplantation, and patients need to be clearly diagnosed under the guidance of a physician.