That normal human blood contains iodine is a matter of rather recent observation, although its presence has been suspected for many years. One of the earliest treatments for goiter was with burnt sponge, and when early in the nineteenth century it was demonstrated that sponges are rich in iodine, the employment of this drug in the therapy of goiter came about inevitably. It was in 1820 that the Swiss physician, Coindet,1 made this clinical application. From that day to this, iodine has been the standard pharmaceutic weapon against all forms of depletion of the thyroid gland.
Yet three quarters of a century elapsed before it was discovered that the thyroid gland is itself an iodine factory. The iodine content of the normal thyroid gland was demonstrated by Baumann2 in 1895, and this discovery led chemists and biologists to endeavor to find out if iodine existed in other body
DeCOURCY JL. IODINE CONTENT OF BLOOD IN CHOLECYSTIC DISEASE. Arch Surg. 1937;35(1):140-147. doi:10.1001/archsurg.1937.01190130143007