Historical Tidbit – Then and Now: This Month in Endocrine History
Submitted by Evan Graber, DO
It is difficult to imagine a time when we did not know what compounds allowed the thyroid gland to exert its physiological effects on the body. Prior to 1914, all that was known was that “1) The thyroid contains some substance capable of producing marked physiologic effects, and (2) iodin is a constant constituent of normal and pathologic glands.” In June 1915, Dr. Edward Kendall reported on the isolation of thyroxine, containing roughly 60% iodine. He reported on how he hydrolyzed thyroid proteins and isolated a crystalline form of the thyroid substance that, when administered to dogs or humans, resulted in an increase in pulse and metabolic rate. He also noted that in hyperthyroidism due to “exophthalmic goiter,” the secretion of the iodine-containing compound and iodine reservoir capacity of the thyroid was increased.
Today, we know the various forms of thyroid hormones, how they are synthesized in the thyroid gland, the distribution of thyroid hormone receptors in different organs, and the physiology behind the various disorders of thyroid hormone production or action. Due to the pivotal discovery by Dr. Kendall, we can now prevent developmental delays caused by congenital hypothyroidism, ensure normal growth in those with autoimmune thyroiditis, and suppress TSH to reduce the recurrence of thyroid cancers.