Written by Keen Meds · Reviewed by Licensed Clinical Providers · March 1, 2026
Key Insight: Testosterone was first chemically synthesized in 1935 — independently by Adolf Butenandt in Germany and Leopold Ruzicka in Switzerland. Ruzicka received the Nobel Prize in Chemistry in 1939 partly for this work.
The word "testosterone" is so familiar today that it is easy to forget the hormone was completely unknown just 140 years ago. No physician in 1880 had a name for it. No laboratory had measured it. No patient had ever received a prescription for it. The entire field of what we now call andrology (the study of male hormonal health) grew out of a small number of experiments conducted between 1889 and 1935.
Understanding where testosterone came from scientifically is not just a matter of historical curiosity. It clarifies something important for patients considering testosterone therapy: testosterone is not a pharmaceutical product invented by a drug company. It is a naturally occurring hormone that scientists spent decades trying to isolate, characterize, and eventually replicate, because they observed what happened when men lacked it.
This post covers the six-decade arc from the first public claim of a male hormonal effect to the chemical synthesis that earned a Nobel Prize.
1889: The Self-Experiment That Started Everything
The story of testosterone research begins with a 72-year-old French-American physician named Charles-Edouard Brown-Sequard. In 1889, Brown-Sequard injected himself subcutaneously with a crude extract derived from the testicles of dogs and guinea pigs. He then reported, in a lecture before the Societe de Biologie in Paris, that he had experienced a dramatic return of physical vigor, mental clarity, and overall vitality.
The medical community's response was swift and largely dismissive. Most contemporaries regarded his claims as implausible or attributed the effects to placebo. Brown-Sequard was a distinguished physiologist with legitimate prior contributions to neuroscience, which may be why the report was published at all. But the scientific establishment of the late nineteenth century had no framework for hormones. The word "hormone" itself would not be coined until 1905.
What Brown-Sequard had identified was not testosterone. His crude extracts almost certainly contained too little active compound to produce genuine pharmacological effects. He was probably experiencing a placebo response. However, his public claim did something that methodologically rigorous science often cannot do: it directed widespread attention toward a question that no one had previously asked systematically. Could something produced in the testes have effects on the rest of the body?
That question became the engine of testosterone research for the next 45 years.
1927: The First Isolation of an Active Substance
The next significant advance came nearly four decades later, at the University of Chicago. In 1927, biochemists Fred Koch and his graduate student Lemuel McGee set out to isolate whatever biologically active substance existed in testicular tissue. The experimental model they used was straightforward: castrate roosters (which causes their combs to atrophy), then administer testicular extracts and measure comb regrowth as a bioassay for androgenic activity.
The challenge was not the assay. It was the starting material. To obtain enough active substance to study, Koch and McGee processed approximately 40 pounds of bull testes, purchased from Chicago slaughterhouses, to obtain a small quantity of lipid-soluble extract. When they administered this extract to castrated roosters, the combs regrew. The experiment demonstrated for the first time that a specific extractable compound from testicular tissue had measurable androgenic effects.
Koch and McGee did not isolate a pure compound or determine its chemical structure. What they established was that the androgenic effect was real, reproducible, and associated with a definable fraction of testicular tissue.
1931: Butenandt and the Urine Experiments
Adolf Butenandt, a German chemist working in Gottingen and later at Danzig, took the isolation project to an extreme scale. In 1931, his team processed approximately 15,000 liters of male urine collected from police barracks in Berlin, evaporating and chemically fractionating the material to obtain a small quantity of a crystalline androgenic compound.
The compound Butenandt isolated was not testosterone. It was androsterone, a weaker androgen that is a metabolic end product of testosterone. Androsterone is produced when testosterone is broken down in the liver and excreted in urine. Butenandt correctly characterized its chemical structure, which placed it within the steroid family and revealed its structural relationship to cholesterol.
The significance of Butenandt's 1931 work was structural. By establishing that androsterone was a steroid derived from cholesterol, he gave chemists a template. If the body could produce an androgenic hormone from cholesterol, then perhaps chemists could as well.
1935: Three Teams, One Year, One Hormone
The year 1935 produced three closely timed milestones that together defined what testosterone is.
In May 1935, a team led by Ernest Laqueur at the University of Amsterdam published a paper describing the isolation of a crystalline substance from bull testes that was more potent in the rooster comb assay than androsterone. Laqueur's team gave this compound its name: testosterone, derived from the Latin "testis" combined with the Greek "stereos" (solid) and the chemical suffix "-one" indicating a ketone group. This was the first time the word appeared in scientific literature.
Within weeks, Adolf Butenandt's group published a paper describing the chemical synthesis of testosterone from cholesterol. Independently and almost simultaneously, Leopold Ruzicka, a Swiss chemist working at ETH Zurich, published a separate synthesis from the same precursor. Both teams had used the structural knowledge built up over the prior decade to engineer the hormone in a laboratory rather than extract it from biological tissue.
The chemical synthesis was a critical advance. It meant that testosterone was no longer dependent on processing enormous quantities of biological material. It could, in principle, be manufactured. And it definitively established that testosterone was a small-molecule steroid hormone derived from cholesterol, not some mysterious vital substance locked in organ tissue.
The Nobel Prize and Its Meaning
In 1939, the Nobel Prize in Chemistry was awarded jointly to Adolf Butenandt and Leopold Ruzicka for their work on sex hormones. Butenandt's prize recognized the androsterone isolation and structural characterization. Ruzicka's prize recognized his synthesis work on sex hormones broadly, including testosterone. Butenandt was initially forced by the Nazi government to decline the prize, though he later accepted it after the war.
The Nobel recognition underscored that this was not merely applied medicine. The discovery and synthesis of the sex steroids was considered among the most important contributions to chemistry in the twentieth century. The structural insights derived from testosterone work also laid the groundwork for later synthesis of cortisone and other steroid hormones that would become essential to twentieth-century medicine.
Why This History Matters for Patients Today
The discovery history of testosterone carries a practical implication for anyone evaluating testosterone therapy today: testosterone is not a synthetic drug invented by a pharmaceutical company. It is a hormone that the human body produces endogenously, that researchers took decades to isolate from biological material, and that scientists eventually learned to synthesize because it occurs naturally in human physiology.
Testosterone replacement therapy, when clinically indicated, does not introduce a foreign substance into the body. It restores a hormone the body already produces, and already depends on, to levels that support normal physiological function.
Understanding Your Testosterone Today
The science that began with Brown-Sequard's 1889 self-experiment and culminated in a Nobel Prize in 1939 established the biological foundation for everything clinicians know about testosterone today. Measuring testosterone, understanding what low levels mean, and offering evidence-based treatment options are all direct extensions of that scientific history.
Keen Meds connects you with licensed clinical providers for a telehealth evaluation and lab review. If your testosterone is clinically low, you may qualify for a prescription for Testosterone Spray Rx -- a needle-free transdermal testosterone program.
