Studies of serum long-acting thyroid stimulator (LATS) in relation to exophthalmos after therapy for thyrotoxicosis.

Abstract

SUMMARYObservations have been made on a series of 30 thyrotoxic patients before and after therapy, with particular attention to exophthalmos (measured by the Hertel exophthalmometer) and serial determinations of serum levels of protein‐bound iodine (PBI) and long‐acting thyroid stimulator (LATS).In 14 cases in which there was an exacerbation of exophthalmos (mean maximal increase of 2·8 mm. Hg) there was a greater fall in serum PBI levels (7.3 µg. per 100 ml.) than in 16 cases in which there was no such exacerbation (3.5 µg. per 100 ml.), although initial serum levels of PBI were the same in the two groups. The serum LATS level was more likely to be initially elevated in the group showing exacerbation. and a further rise was observed more frequently in this group following therapy, whether with antithyroid drugs, surgery or radio‐iodine.Suppression of serum levels of LATS with azathioprine or steroids did not significantly affect the exophthalmos which had already developed in two cases.These observations suggest that a determination of serum level of LATS could be carried out advantageously before therapy. If a high level is seen, then exacerbation of exophthalmos is more likely to occur. Immunosuppressive therapy may be indicated in addition to antithyroid drug therapy. surgery or the use of radio‐iodine if exacerbation is to be prevented.Further studies are suggested to try to define more clearly the susceptible group of patients and to assess the value of immunosuppressive therapy in preventing exacerbations of exophthalmos.