Does thyroid function influence serum beta 2-microglobulin?

In 24 patients with hyperthyroidism (15 with Graves' disease and 9 with toxic nodular goitre), serum beta 2-microglobulin (beta 2-m) levels were measured prior to and during 6 wk of treatment with carbimazole. The same schedule was followed in 7 patients with hypothyroidism, but their treatment consisted of levothyroxin in increasing doses. In 16 of the patients with hyperthyroidism, beta 2-m was initially found to be increased. In all these patients an increased beta 2-m declined to normal or near-normal levels. The patients with hypothyroidism had a normal medium serum beta 2-m. During substitution there was a tendency for the serum beta 2-m to decline. Indirect arguments are stated for the hypothesis that both in Graves' disease and in toxic nodular goitre activated T-lymphocytes are modulated in their function by carbimazole acting as an immunosuppressing agent. Moreover, we conclude that thyroid hormone levels are not directly responsible for the increased serum beta 2-m concentrations in hyperthyroidism.