The first organ transplant in 1883 was undertaken to reverse the undesirable consequences of a previous thyroidectomy. Theodor Kocher had introduced the practice of removing the whole organ—instead of the usual process of reducing the organ’s size by partial excision—in order to prevent the recurrence of goiter. Kocher had so perfected his surgical technique that he was able to remove the whole gland in a series of patients without having them die. He did not notice the consequences of the removals until later.

Goiter was a serious medical problem. Before Kocher’s time, it was not uncommon for doctors to have to stand by and watch a patient be asphyxiated by his goiter. A surgical solution to the goiter problem only became conceivable once antisepsis, anesthesia, and improved surgical techniques had helped surgery extend its domain to more and more regions of the body. At first, most of this new surgery was concerned with resection: based on a localistic understanding of disease, surgeons would often remove pathological tissue, such as tumors, inflammations, and abscesses, and goiter was among the diseases that were localized and could therefore be removed surgically. A goiter operation was one of several typical resections performed in that period, comparable to amputation and ovariotomy. However, surgeons had long refused to do the operation. Their inability to handle the technical difficulties, and in particular patients’ blood loss, had resulted in a prohibitively high mortality rate. Only in the 1860s and 1870s did the operation become more common—a development that Kocher saw as “excellent proof of the rise of operative surgery.” It was mainly Kocher himself who developed the surgical techniques necessary to master this intervention.

The function of the thyroid as an organ remained in the dark, however, and doctors could do no more than guess at its purpose. Even leading physiologists such as Claude Bernard had no clue. Surgeons therefore tacitly assumed that the thyroid had no function at all, as Kocher wrote retrospectively.