An Exophthalmos-Producing Substance in the Serum of Patients Suffering From Progressive Exophthalmos*

IN A recent publication from this laboratory (1) the separation of the exophthalmos-producing substance (EPS) and the thyroid-stimulating hormone (TSH) of the anterior pituitary was described. In this previous investigation a crude quantitative assay for EPS was made, using the common Atlantic “minnow,” Fundulus heteroclitus, Linn. (2), as the test object. It has been observed that these fish under proper conditions will respond with measurable exophthalmos when a dose as small as 15 micrograms of a dry EPS preparation is given. During the past several years, while the foregoing studies were in progress, efforts were simultaneously made to demonstrate an exophthalmosproducing substance in the serum of patients suffering from the severe or progressive exophthalmos sometimes associated with Graves' disease. Recent success in demonstrating EPS in human serum has prompted this preliminary report.