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Pursuit of Six Pack Abs May Trigger New Malady - Low testosterone & Exercise
  MedPage Today Published: June 23, 2010
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* Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
SAN DIEGO -- Males presenting with high athletic stress or weight loss, coupled with low testosterone, may signal the rise of a new disorder -- functional hypogonadotrophic hypogonadism.
Just as women whose bodies are under stress from excessive exercise, weight loss, or psychological stress can experience hypothalamic amenorrhea, a seven-patient series suggests that a similar phenomenon may exist among men undergoing similar kinds of stress, Andrew Dwyer, MD, of Massachusetts General Hospital, said during a poster session here at the annual meeting of the Endocrine Society.
"We saw some male patients who all have a similar type of presentation in terms of one or more of this [stress] triad, and presented with low testosterone," Dwyer explained. The patients all had normal puberty and a normal testicular size, but all presented with "vague, non-specific symptoms" of low testosterone, including absent morning erections, low energy level, fatigue, decreased athletic performance, and decreased libido, he said.
"Interestingly, two of these patients had female family members with amenorrhea, which made us think maybe there's a connection," Dwyer continued.
To further study this phenomenon, the patients were recalled to the hospital, where they underwent detailed genotyping and phenotyping, including measurements of reproductive and metabolic hormones, an overnight frequent sampling study of leutinizing hormone, and DEXA scan for body composition. The investigators also recruited 35 age-matched healthy adults as controls.
The seven patients had a lower average weight compared to controls (64.1 kg versus 79.9 kg, P<0.01). They also had a lower body mass index (20.7 versus 24.9, P<0.01) and a lower percentage of body fat (9.8% versus 17.6%, P<0.01).
In terms of their biochemical characteristics, the patients had lower serum testosterone compared with controls (168 ng/dL versus 534 ng/dL, P<0.001), lower serum estradiol (12.4 pg/ml versus 37.5 pg/ml, P<0.001), and lower serum leutinizing hormone (LH) (7.2 IU/L versus 9.9 IU/L, P<0.05).
The patients also had lower pulse frequency, lower mean LH amplitude, and lower serum FSH, but none of those numbers approached statistical significance, according to the investigators.
Despite their low testosterone levels, six of the seven patients had LH pulse patterns, frequency, and amplitude that were no different from controls, Dwyer said. However, the seventh patient had four hours of no pulses, then a burst of three pulses, then no pulses for the remaining four hours, a pattern that normally occurs when boys first enter puberty.
"It's as if this patient is recapitulating an early- to mid-pubertal LH pulse secretion pattern," he said. "He's 17, he went through normal puberty, he's done and he's virilized, but with the stress of exercise and the weight loss, perhaps the stress tipped him back into the nocturnal pulse pattern."
Dwyer noted that after the patients had been tested, one of them sustained a heel injury and had to stop training for a while. "He gained six pounds, and we measured his testosterone level, and serially, it stayed normal," he noted. "So with just enough removal of stress...he was able to swing back into normal testosterone production."
Another patient who decreased his training upon the researchers' recommendation was also retested and his testosterone level was up into the low end of the normal range, said Dwyer.
The researchers are calling the possible new disorder functional hypogonadotrophic hypogonadism. "In Boston, there are lots of marathon runners and collegiate rowers who exercise a lot and don't exhibit these symptoms," he said. "So what is it about these seven men that make them different from vast majority of superexerciser lean guys?"
The investigators hypothesize that these men may harbor mutations in genes that are involved in GnRH androgyny or reproductive access such that with the right stressor, that can tip them into hypogonadism, but if you remove the stressor they tip back," said Dwyer.
Rick Dorin, MD, chief of endocrinology at the University of New Mexico, in Albuquerque, said the study was very interesting.
"I see a painfully large amount of hypogonadism in in my clinical practice at the Veterans Affairs Hospital," said Dorin, who was not involved in the study. "We see a lot of hypogonadism due to other factors, but not in such young men. This is raising the possibility that the [hypothalamic amenorrhea] in women athletes -- that a comparable thing goes on in young men. They've got provocative findings in a small number of patients."
The study was funded by the National Institutes of Health. Dwyer and Dorin each reported having no conflicts of interest.
Primary source: The Endocrine Society
Source reference:
NR Chavan, AA Dwyer, PW Butler, MT Collins, GP Sykiotis, KW Keefe, SB Seminara, L Plummer, WF Crowley, N Pitteloud. "Male functional hypogonadotropic hypogonadism (MFHH): A distinct clinical entity?" ENDO 2010; Abstract Book, P2-462.
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