"Man, oh man," read the words emblazoned on a white tent set up in the pedestrian zone of the German city of Erfurt. Those who ventured inside received information on a dramatic scientific finding: One in three men over the age of 60 suffers from "testosterone deficiency syndrome." If left untreated, this dastardly condition can cause excess weight, anemia, hot flashes, osteoporosis, lowered sex drive and bad moods.

This same tent will be making appearances through November in Augsburg, Saarbrücken, Hanover and other German cities. Here, men over the age of 40 can have their testosterone level checked at no cost. They can also learn how to counteract testosterone deficiency: either get more exercise, or apply testosterone gel to their skin.

This traveling testosterone counseling service provided by the "German Society for Men and Health" was not born out of a purely charitable impulse -- there is a marketing angle at work here as well. The organization is funded by pharmaceutical company Jenapharm, the leading manufacturer of testosterone gel.

It's one of five companies that sell the male sex hormone, which is rubbed into the skin, and business couldn't be better. This can be seen in the number of prescriptions issued through Germany's statutory health insurance funds. The Scientific Institute of AOK, one of Germany's largest insurers, analyzed this data on behalf of SPIEGEL and found that prescriptions for testosterone gel more than tripled between 2003 and 2011. The most recent statistics show 390,000 daily doses per year. In Germany, a month's supply of the product costs around 60 ($80).

Unnecessary Prescriptions

These gels are also doing a roaring trade in other countries, such as Switzerland and the United States. A survey of over 10 million members of one American health insurance company showed that nearly 3 percent of all men over 40 are now prescribed testosterone. At the same time, this analysis also revealed that, medically speaking, most of these prescriptions were unnecessary.

The testosterone trend comes with attendant risks. Used in excess, the male hormone can promote the growth of prostate cancer and increase the risk of heart attacks and strokes. American doctors Lisa Schwartz and Steven Woloshin recently warned in the medical journal JAMA Internal Medicine that this widespread use of testosterone is "a mass, uncontrolled experiment that invites men to expose themselves to the harms of a treatment unlikely to fix problems ... that may be wholly unrelated to testosterone levels."

The booming business in testosterone gel provides a prime example of the ways in which pharmaceutical companies exaggerate illnesses to create new markets for their products.

Experts agree that men with hypogonadism -- in which the testicles produce little or no testosterone -- do indeed benefit from receiving supplements of the hormone. But few men actually suffer from serious hypogonadism. So when the newly developed testosterone gel hit the market, doctors and pharmaceutical companies looked for other symptoms the product might treat -- and found them in male menopause.

The idea of male menopause -- also known as andropause or male climacteric -- existed even in ancient times. The Romans considered age 63 to be a dangerous moment of change, and congratulated one another for having survived this "annus climactericus maximus."

Salt Baths and Cold Rubdowns

Around 100 years ago, some neurologists observed a menopause-like change in men. Berlin neurologist Kurt Mendel, for example, believed he had diagnosed a "very noticeable tendency toward emotional reactions and crying, which had not previously been present" among his older male patients. He prescribed salt baths and cold rubdowns.

Later, with advances in the study of glands, this supposed andropause was explained as being a hormone deficiency. Chemists at first obtained testosterone by extracting it from bulls' testicles by the ton and male human urine by the hectoliter, before achieving laboratory production of artificial testosterone in 1935.

"But it wasn't until the late 1960s, as the field of andrology expanded, that medical attention began to turn once again to the male climacteric," says medical historian Hans-Georg Hofer, 41, at Bonn University. Neologisms such as "andropause" and "PADAM" -- for "Partial Androgen Deficiency in Aging Men" -- started to catch on.

The idea of andropause took off in earnest a few years ago, when scientists developed a way to administer testosterone as an easy-to-use gel, rather than through shots and patches. Suddenly there was a new epidemic, too, to match this new product. In March 2003, pharmaceuticals company Jenapharm announced that male climacteric affects "at least 2.8 million Germans, according to epidemiological estimates."

Jenapharm then hired Hermann Behre, director of the Center for Reproductive Medicine and Andrology at Halle University Hospital, to speak at a press conference about testosterone gel. Behre will also speak at an upcoming "Jenapharm Symposium" on testosterone in Münster this December.