β2-Microglobulin (β2-M) is a single polypeptide chain containing 100 amino acids and is found on the surface of nucleated cells. β2-M is continuously secreted into the circulatory system and therefore maintains a balanced serum level.
Decreases in the glomerular ﬁltration rate gives rise to increases in the level of β2-M.
β2-M is a helpful marker in the diagnosis of kidney disease and active rheumatoid arthritis.
Patients with acquired immune deﬁciency syndrome (AIDS) show an increased level of β2-M.
β2-M has a low concentration in serum. We have found in a normal unselected population that in serum the highest level for β2-M is 3.8 mg/L. The total number of serum samples tested was 92, showing little differences in the normal level in males, pre- and postmenopausal females. The average for male samples = 1.582 mg/L, for premenopausal female = 1.457 mg/L, for postmenopausal female = 1.608 mg/L and ﬁnally for young people = 1.13 mg/L.