Alpha 1 microglobulin is an indicator of renal tubular function. alpha 1 microglobulin is mainly synthesized by the liver and lymphocytes, which is filtered through the glomerulus and basically reabsorbed in the renal tubules. Therefore, if the renal tubular reabsorption ability is reduced and the renal tubular function is damaged, high α1 microglobulin will occur. In addition, for all causes of renal impairment, α1 microglobulin will be elevated. Because α1 microglobulin is synthesized by the liver, it may also lead to high α1 microglobulin if liver cancer occurs. In addition, it is also seen in patients with lgA myeloma. Therefore, when a1 microglobulin is high, it is important to visit a hospital promptly to clarify the cause.