Myasthenia Gravis Hormone-Based?
New evidence in guinea pigs suggests that increased amounts of a hormone released from the thymus contribute to human myasthenia gravis.These increased levels of the substance, called thymin, cause both myopathic changes and the characteristic neuromuscular block seen in the disease, said Gideon Goldstein, MD, PhD, formerly a visiting scientist at the National Institute of Allergy and Infectious Diseases, Bethesda, Md.The neuromuscular block occurs only after prolonged parenteral administration of thymin, these studies show. This accounts for earlier failures to demonstrate such block-age with large, single-dose injections of thymic extract, Dr. Goldstein said.Thymin is present in the normal thymus, and appears to be secreted in small amounts. It is the inflamed thymus, producing abnormal amounts of the substance, which appears to produce myasthenic muscle blockage. The cause of such inflammation is not known, but is probably related to an autoimmune reaction, Dr. Goldstein