Thyroid Disorders: History and Discovery

The story of the thyroid is a story told backwards. People treated a swollen neck for thousands of years before anyone knew there was a gland there; they named the gland centuries before anyone knew what it did; and they learned what it did only when surgeons, by removing it, accidentally created the disease its absence causes. Goiter was described in antiquity and treated empirically with seaweed and burnt sea sponge — foods we now know are rich in iodine — long before iodine itself was discovered in 1811. This page traces that long arc: the naming of the gland by Thomas Wharton in 1656, the discovery of iodine and its first use against goiter, the recognition that a missing thyroid is deadly, and the chemical isolation and synthesis of the hormone thyroxine. (Graves' disease and Hashimoto's thyroiditis have their own dedicated history within the linked pages below.)

Goiter in Antiquity: Seaweed and Burnt Sponge
Naming the Gland: Thomas Wharton, 1656
The Discovery of Iodine, 1811
Coindet Treats Goiter with Iodine, 1820
Proof the Gland Matters: Myxedema and Kocher
Eugen Baumann Finds Iodine in the Thyroid, 1895
Isolating and Synthesizing Thyroxine, 1914–1927
David Marine, Akron, and Iodized Salt
From Discovery to Modern Care
Research Papers and References
Connections

Goiter in Antiquity: Seaweed and Burnt Sponge

Long before anyone understood the thyroid gland, people recognized and tried to treat the swelling it can cause. An enlarged thyroid — a goiter, the conspicuous lump or fullness at the front of the neck — is one of the oldest recorded human afflictions. Ancient Chinese medical writings, traditionally dated to the second millennium BCE, describe these neck swellings and record a remedy arrived at purely by trial and error: eating seaweed and burnt sea sponge. Neither the physicians who prescribed it nor the patients who took it had any idea why it worked. We now know the reason — seaweed and marine sponge are among the richest natural sources of iodine, and most goiter throughout history was caused by iodine deficiency — but that explanation lay more than three thousand years in the future.

The same empirical remedy surfaces repeatedly across the ancient and medieval world. The Greek tradition associated with Hippocrates and later the physician Galen recommended burnt sponge for neck swellings, and by the twelfth century the burnt-sponge treatment for goiter was being taught at the School of Salerno, one of the first formal medical schools in Europe. This is a striking case of the right treatment for the wrong reason: a chain of practitioners, separated by oceans and centuries, all converged on iodine-bearing sea products as a cure for goiter without any concept of an element, a gland, or a hormone. The accumulated folk and clinical wisdom was correct; only the mechanism was missing.

It is worth being precise about what was and was not known. Antiquity recognized the swelling and found an empirical treatment, but it had no concept of the thyroid as a distinct organ with a function, no concept of iodine, and no understanding of cretinism and hypothyroidism as iodine-deficiency states. Each of those insights had to be discovered separately, and the rest of this page follows them in turn.

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Naming the Gland: Thomas Wharton, 1656

The thyroid gland received its modern name from the English physician and anatomist Thomas Wharton (1614–1673) in his 1656 Latin treatise Adenographia ("a description of the glands of the whole body"), the first systematic account of the human glands. Wharton called the structure glandula thyreoidea — the "thyroid gland." The same volume is remembered for two other eponyms still in use today: Wharton's duct (the submandibular salivary duct) and Wharton's jelly (the gelatinous tissue of the umbilical cord).

The name itself encodes a small piece of anatomical history, and it is worth getting the chain of naming right. The Greek word thyreos (θυρεóς) meant an oblong, door-shaped shield — the large shield a soldier stood behind. Greek anatomists had already applied thyreoeides ("shield-shaped") to the large cartilage of the voice-box, which we still call the thyroid cartilage (the prominence of the "Adam's apple"). Wharton named the gland not because the gland looks like a shield, but because it sits in close contact with that shield-shaped cartilage. So the lineage runs: a soldier's shield → the shield-shaped laryngeal cartilage → the gland lying against it. This is a naming-of-the-organ event, entirely separate from any knowledge of what the organ does — which remained almost a complete mystery for another two centuries.

Wharton himself, like his contemporaries, could only guess at the gland's purpose. Suggested functions in the seventeenth and eighteenth centuries ranged from lubricating the larynx to rounding out the contour of the neck for the sake of appearance. The notion that the thyroid is a ductless gland pouring a chemical messenger directly into the blood — the very idea of an internal secretion or hormone — did not exist yet and would not arrive until the late nineteenth century.

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The Discovery of Iodine, 1811

The element at the centre of thyroid biology was discovered by accident, and in the service of war. In 1811 the French chemist and saltpetre manufacturer Bernard Courtois (1777–1838) was extracting sodium and potassium salts from seaweed ash, a raw material used in making gunpowder during the Napoleonic Wars. When he added too much sulfuric acid to the ash, a startling violet vapour rose from the vat and condensed into glittering dark, metallic-looking crystals. Courtois had isolated a previously unknown element. He shared samples with other chemists, and within two years the celebrated scientists Joseph Louis Gay-Lussac and Humphry Davy had characterized it and agreed it was a new element. Gay-Lussac named it iode, from the Greek ioeides ("violet-coloured"), after the colour of its vapour — the origin of the English word iodine.

The connection to the thyroid was not obvious at the time, and it is important not to read it backward into 1811. Courtois discovered an element; he did not discover anything about goiter, the thyroid, or human health. But the source of his iodine — seaweed ash — quietly hints at the link that medicine would soon make: the same marine plants that ancient physicians had burned to treat goiter were rich in exactly this new element. The stage was set for someone to connect the empirical sea-sponge remedy of antiquity with the freshly discovered chemistry of iodine.

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Coindet Treats Goiter with Iodine, 1820

That connection was made in Geneva by the physician Jean-François Coindet (1774–1834). Reasoning that the long-standing burnt-sponge and seaweed remedies for goiter probably worked because of their iodine content — the element that had just been discovered — Coindet tried giving patients iodine directly, as an alcoholic tincture, rather than as sponge. The results were rapid and dramatic: he reported substantial shrinking of goiters within roughly a week or two of starting treatment. He announced his findings publicly in Geneva on 21 July 1820 in a paper whose title translates as "Memoir on the discovery of a new remedy against goiter," following it with further reports in 1820 and 1821.

Coindet's work was the first deliberate, rational use of iodine against a thyroid disorder, and it effectively explained two thousand years of folk medicine in a single stroke: the active principle of the ancient burnt sponge was iodine. His insight also carried an early warning that still matters today. Because he was giving relatively large, uncontrolled doses, some patients developed symptoms of iodine excess — including a racing heart, weight loss, and agitation, which we now recognize as iodine-induced hyperthyroidism. This made him one of the first to document, however unintentionally, that too much iodine can be as harmful as too little, a balance that runs through the whole history of thyroid disease.

One further nineteenth-century idea belongs here, clearly labelled as the hypothesis it was. In 1852 the French chemist Adolphe Chatin proposed that endemic goiter and cretinism were caused by a deficiency of iodine in the environment — in the water, soil, and food of mountainous regions. This was a hypothesis, not a proof: Chatin lacked the means to demonstrate it conclusively, and his idea was disputed and largely set aside for decades. It was nonetheless essentially correct, and it was finally vindicated by later discoveries — the finding of iodine inside the thyroid itself, and the controlled prevention trials of the early twentieth century — described below.

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Proof the Gland Matters: Myxedema and Kocher

Through all of this, no one had yet shown that the thyroid gland itself was essential to life. That proof came in the second half of the nineteenth century from two directions at once — the bedside and the operating table — and together they revealed that a thyroid which fails, or which is removed, produces a devastating illness. In London, the eminent physician Sir William Withey Gull presented cases in 1873–1874 of what he called "a cretinoid state supervening in adult life in women": middle-aged patients who became slow, cold, puffy, and mentally dulled, a condition Gull linked to wasting (atrophy) of the thyroid. A few years later his colleague William Miller Ord studied the characteristic doughy, non-pitting swelling of the skin in these patients and coined the name that stuck: myxoedema (literally "mucous swelling"), introduced in 1877. (The condition is the severe adult form of what we now call hypothyroidism.)

The decisive evidence came from surgery, and it came as a disaster. In Switzerland, the Bern surgeon Emil Theodor Kocher (1841–1917) was perfecting the operation to remove enormous goiters, reducing what had been a horrifyingly lethal procedure to one of the safest in surgery. But when he and others removed the thyroid entirely, many patients — especially children and young people — slid into a wretched state of mental and physical decline: sluggishness, swelling, stunted growth, and cognitive loss. Kocher reported this in 1883 and called it cachexia strumipriva ("the wasting of thyroid deprivation"). The lesson was unmistakable and, in hindsight, profound: the gland anatomists had named two centuries earlier without knowing its purpose was in fact vital, and the myxedema seen by physicians at the bedside and the post-surgical collapse seen by Kocher were one and the same disease, hypothyroidism, arrived at by two different routes.

This discovery transformed thyroid medicine. If removing the gland caused the disease, then replacing what the gland made might cure it — and in 1891 the Newcastle physician George Murray demonstrated exactly that, successfully treating a myxedema patient with injections of sheep-thyroid extract. It was the first effective hormone-replacement therapy in medical history, and it was soon simplified to feeding patients dried thyroid by mouth. Kocher, for his pioneering work on the physiology, pathology, and surgery of the thyroid, was awarded the Nobel Prize in Physiology or Medicine in 1909 — the first surgeon ever to receive it.

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Eugen Baumann Finds Iodine in the Thyroid, 1895

The threads of iodine and of the gland had been running in parallel for the better part of a century. They were finally tied together by the German biochemist Eugen Baumann (1846–1896), who in 1895 made a discovery that astonished his contemporaries: the thyroid gland naturally contains iodine. Until then no one suspected that this rare element, known chiefly from seaweed and chemistry laboratories, was a normal constituent of a human organ. The following year, in 1896, Baumann went on to isolate from thyroid tissue an iodine-rich substance he called iodothyrin (also rendered thyroiodine), which he found could relieve myxedema — the first chemical glimpse of the active material the gland produces.

Baumann's finding was the conceptual keystone of the whole story. It explained, all at once, why the ancient seaweed-and-sponge remedies had worked, why Coindet's iodine shrank goiters, and why Chatin's iodine-deficiency hypothesis pointed in the right direction: the thyroid needs iodine to do its job, and goiter is largely the gland's response to not having enough. For the first time, antiquity's empirical cure, the new element of 1811, and the vital gland of Gull and Kocher all locked into a single coherent picture. What remained was to identify and purify the specific iodine-containing hormone itself.

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Isolating and Synthesizing Thyroxine, 1914–1927

The hormone was captured in the United States. At the Mayo Clinic in Rochester, Minnesota, the biochemist Edward Calvin Kendall (1886–1972) succeeded in isolating the active thyroid compound in pure crystalline form on Christmas Day, 1914 — the breakthrough crystals appearing, by his account, after he had worked through the night of 23–24 December extracting an enormous quantity of hog thyroid glands (on the order of three tonnes of tissue). He named the substance thyroxine and published the isolation in 1915. It was a landmark not only for thyroid medicine but for endocrinology as a whole: thyroxine was one of the very first hormones ever obtained in pure form, isolated only about nine years after the word "hormone" had even been coined.

Kendall isolated the hormone but did not establish its exact chemical structure. That was accomplished in London by Charles Robert Harington (1897–1972) at University College Hospital Medical School, who worked out the correct structure of thyroxine in 1926. The very next year, 1927, Harington joined forces with the chemist George Barger (of the University of Edinburgh) to synthesize thyroxine from scratch in the laboratory, confirming the structure beyond doubt and making the hormone available without grinding up thyroid glands. Their synthesis is still admired as a tour de force of organic chemistry; the structure showed thyroxine to be a tetra-iodinated derivative of the amino acid tyrosine — in other words, a small iodine-laden molecule, which is precisely why the gland must have iodine to make it.

Kendall is often, and fairly, remembered as one of medicine's great hormone hunters: years later, at the same Mayo Clinic, his work on the adrenal hormones — including the substance that became cortisone — earned him a share of the 1950 Nobel Prize in Physiology or Medicine. The isolation of thyroxine in 1914 and its synthesis by Harington and Barger in 1927 together completed the chemical chapter of thyroid history: the gland, the element, and now the exact hormone were all finally in hand. The modern synthetic form of this same molecule, levothyroxine, remains one of the most-prescribed medicines in the world for treating an underactive thyroid.

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David Marine, Akron, and Iodized Salt

Knowing that the thyroid needs iodine is one thing; proving you could prevent goiter in a whole population by giving it is another, and that proof was furnished in Ohio. The pathologist David Marine (1880–1976), who had earlier shown in animals that iodine controls goiter, set out with the medical student Oliver Kimball to test the idea in people. Between 1917 and 1920 they ran a large controlled trial among schoolgirls in Akron, Ohio, then part of the American "goiter belt" around the Great Lakes where the soil and water are poor in iodine. Some two thousand girls received small doses of iodine; a comparable group who did not serve as controls. The difference was overwhelming — goiter newly developed or worsened in only a tiny fraction of the iodine-treated girls compared with a large fraction of the untreated ones.

This was one of the first great controlled prevention trials in American public health, and its conclusion was inescapable: a trace of iodine reliably prevents endemic goiter. Marine became a forceful advocate for adding iodine to ordinary table salt as the cheapest, simplest way to reach an entire population. Encouraged by his results — and by news of a parallel salt-iodization effort in Switzerland — the United States introduced iodized salt, first sold in Michigan in 1924. The effect on the goiter belt was profound: endemic goiter and iodine-deficiency cretinism, once common across whole regions, faded within a generation. Salt iodization is now regarded as one of the most successful and cost-effective public-health measures ever undertaken, and it is the direct, practical descendant of the entire chain of discovery on this page — from burnt sponge, to the element iodine, to iodine inside the gland, to a pinch of it in the salt cellar.

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From Discovery to Modern Care

Within little more than a single lifetime — from Gull's 1873 cases to Marine's iodized salt of the 1920s — thyroid disease was transformed from a baffling collection of neck swellings and mysterious wasting illnesses into one of the best-understood and most treatable areas of medicine. The gland named by Wharton in 1656 turned out to be a master regulator of the body's metabolism; the violet element discovered by Courtois in 1811 turned out to be its essential fuel; and the hormone isolated by Kendall in 1914 and synthesized by Harington and Barger in 1927 turned out to be makeable in a factory and swallowable as a daily tablet.

Everything that follows in modern thyroid care grows out of these foundations. The recognition that the gland makes a hormone led, in the twentieth century, to blood tests that measure thyroid hormones and the pituitary signal (TSH) that controls them, so that an underactive or overactive thyroid can now be diagnosed from a few drops of blood rather than from a visibly swollen neck. The understanding that the gland concentrates iodine led to radioactive iodine — used both to image the thyroid and to treat an overactive gland or thyroid cancer by delivering radiation precisely to the tissue that absorbs it. And the synthesis of thyroxine led directly to today's standard treatment for the underactive thyroid: a small daily dose of levothyroxine, chemically identical to the hormone the body makes.

The specific autoimmune diseases that account for most thyroid disorders today — Graves' disease, the leading cause of an overactive thyroid, and Hashimoto's thyroiditis, the leading cause of an underactive one — have their own rich discovery histories, told on their dedicated pages linked below. But all of them rest on the deeper foundation laid out here: that there is a gland at the front of the neck, that it runs on iodine, and that the hormone it makes is essential to human life. Those three facts, won slowly over more than three centuries, are the bedrock of everything modern medicine does for the thyroid.

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Research Papers and References

The references below combine landmark primary papers with peer-reviewed historical reviews and curated PubMed topic-search links into the history of the thyroid, iodine, and thyroxine. Historical primary sources predating modern indexing — such as Wharton's Adenographia (1656), Coindet's 1820 Geneva memoir, and Kocher's 1883 report — are named in the article as historical sources; the items below are the modern, verifiable record. Each external link opens in a new tab.

Slater S. The discovery of thyroid replacement therapy. Part 1: In the beginning. Journal of the Royal Society of Medicine. 2011;104(1):15–18. — doi:10.1258/jrsm.2010.10k050
Kendall EC. The isolation in crystalline form of the compound containing iodin, which occurs in the thyroid: its chemical nature and physiologic activity. JAMA. 1915;64(25):2042–2043. — doi:10.1001/jama.1915.02570510018005
Harington CR, Barger G. Chemistry of thyroxine. III. Constitution and synthesis of thyroxine. Biochemical Journal. 1927;21(1):169–183. — doi:10.1042/bj0210169
Laios K, Lagiou E, Konofaou V, et al. From thyroid cartilage to thyroid gland. Folia Morphologica. 2019;78(1):171–173. — doi:10.5603/FM.a2018.0059
Lindholm J, Laurberg P. Hypothyroidism and thyroid substitution: historical aspects. Journal of Thyroid Research. 2011;2011:809341. — doi:10.4061/2011/809341
Thomas Wharton, Adenographia (1656) and the naming of the thyroid gland — PubMed: Wharton, Adenographia, and the thyroid
Bernard Courtois and the discovery of iodine (1811) — PubMed: Courtois and the discovery of iodine
Jean-François Coindet and the treatment of goiter with iodine (1820) — PubMed: Coindet, iodine, and goiter
Eugen Baumann and the discovery of iodine in the thyroid (1895–1896) — PubMed: Baumann and iodine in the thyroid
Theodor Kocher, thyroid surgery, and the 1909 Nobel Prize — PubMed: Kocher, thyroid surgery, and the Nobel Prize
William Gull, William Ord, and the description of myxoedema — PubMed: Gull, Ord, and myxoedema
Charles Harington and the structure and synthesis of thyroxine — PubMed: Harington and the structure of thyroxine
David Marine, the Akron goiter study, and iodized salt — PubMed: David Marine, Akron, and iodized salt
History of iodine deficiency disorders and salt iodization — PubMed: history of iodine deficiency and salt iodization

External Authoritative Resources

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Connections

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