爆火的睾酮替代疗法，真的安全吗？｜科学60秒

睾酮替代疗法作为一种医疗手段，原本用于治疗一种名为“低睾酮症”（Hypogonadism）的疾病，患有该病的男性，其睾丸可能因遗传、疾病、损伤等问题而无法产生足够睾酮。从“替代”一词就能看出，睾酮替代疗法旨在将过低的睾酮水平“补”回正常范围。

人工合成睾酮的历史十分悠久，最早可追溯至 1935 年。彼时，睾酮的化学结构刚刚确定，德国科学家阿道夫·布特南特（Adolf Butenandt）和瑞士科学家利奥波德·鲁日奇卡（Leopold Ružička）就分别成功实现了人工睾酮的合成。这项成就也使他们共同获得了 1939 年的诺贝尔化学奖。

长期以来，人们一直认为睾酮替代疗法可能导致前列腺癌，或许还会引发心血管疾病，如中风或突发心脏病。近几年的研究发现，睾酮替代疗法并不会引发这些严重的副作用和并发症。但关于其对长期健康的影响，我们仍然知之甚少。

在美国，很多私人诊所可以为顾客提供这种自费治疗。在社交媒体上，人们正在用它治疗各种症状和疾病，从增肌、缓解疲劳，再到解决情绪问题，睾酮替代疗法似乎正被包装成一种能治愈一切疾病的万能神药。

至于睾酮替代疗法的实际益处，目前的科学证据主要集中在那些被确诊为睾酮水平过低的男性群体中。

医学上的确存在低睾酮病，但具体多低的水平才能算作低睾酮，业内并没有达成一个统一的共识。这是因为人体激素水平的基线值可能存在着巨大的个体差异。与避孕或更年期激素替代疗法等激素类治疗相类似，不同人对激素的反应可能千差万别。

有证据表明，睾酮水平偏低的男性如果同时患有重度抑郁症，该疗法则可能有助于改善情绪、提升精力。睾酮替代疗法疗效的研究中最明确的结论是，它能让睾酮水平过低的男性提升性欲，因为睾酮可以作用于大脑，从而增加性冲动和欲望。

有很多接受这种疗法的男性，其体内的睾酮水平并不处于过低状态，对于他们而言，睾酮替代疗法能够带来益处的证据就少得多。目前，除了额外的增肌效果之外，尚不清楚是否还有其他显著的正面效果。

尽管此前研究表明，睾酮替代疗法与前列腺癌之间的关联并不像过去担心的那样严重，但这并不意味着它没有其他潜在的负面影响，尤其是在睾酮水平正常的男性身上。

当一个男性开始接受外源性睾酮补充时，为了响应这一变化，人体会启动一个精密的负反馈循环。这一机制会向大脑发出信号：“血液中的睾酮水平已经很高了，我们需要减少自身产量。”接着，身体就会显著减少，甚至停止自体睾酮的分泌。

如果男性在并不缺乏睾酮的情况下服用了大量睾酮，其带来的重要副作用就是对生育能力的影响。睾酮会参与精子的生成，当自体睾酮生产被抑制时…… [查看全文]

Testosterone Therapy Is Booming. But Is It Actually Safe?

RachelFeltman: For Scientific American’s Science Quickly, I’m Rachel Feltman.

Whether it’s framed as a cure-all for fatigue and low libido or a shortcut to gaining muscle mass, testosterone replacement therapy, or TRT, is all over the Internet these days. But how much of the hype is actually backed by science?

Here to help us make sense of the testosterone boom is Stephanie Pappas, a freelance reporter based in Colorado. Stephanie recently covered the growing popularity—and availability—of TRT for Scientific American.

Thanks so much for coming on to chat.

Stephanie Pappas: Thank you.

Feltman: So you recently wrote about testosterone replacement therapy for Scientific American. For folks who are not on the right part of the Internet to have heard all about this—or maybe staying off the wrong parts [laughs] of the Internet, depending on your perspective—what’s going on with TRT right now?

Pappas: Well, testosterone replacement therapy has become extremely popular. It has been something that’s been in the background for many, many years. Synthetic testosterone was first invented in 1935, but for a long, long time people thought that testosterone replacement, if it was used for any kind of symptoms men might be having, that it could cause prostate cancer. And then it was believed, perhaps, it could cause heart disease or cardiovascular events like a stroke or a heart attack.

As it turns out the last few years we found that it doesn’t really cause these really serious events. However, a lot less is known about the long-term health impacts. People are really flocking to TRT largely as a result of word of mouth. There are a lot of private clinics that offer this out of pocket, so you don’t have to have an insurance company agree that you need it. And people on social media are using it for just a litany of different symptoms, and it can be anything from muscle-building to fatigue to mood problems and irritability, and it’s kind of being pitched as a cure-all for a lot of different things.

Feltman: And what evidence is there for the benefits of testosterone replacement therapy, maybe starting with people who actually have low testosterone?

Pappas: Yeah, so there is such a thing as low testosterone. No one exactly agrees on what the cutoff is, and probably that’s because there’s a lot of variability in our hormones—like, anyone who’s ever tried any sort of hormone treatment, including birth control or HRT [hormone replacement therapy], can tell you that people respond really differently.

So for men who really do have low testosterone, the evidence suggests that you can see some benefits in mood if you have major depression. You may see some improvements in energy. The most well-established result from the studies of TRT is that you’ll probably see a little boost in libido if you have low testosterone and you now start taking TRT, and that’s because testosterone works in the brain to increase sexual desire.

Feltman: Hmm.

Pappas: For men who don’t have low testosterone, which are many of the men who are now getting treatment, the evidence for benefits is much, much lower. We don’t know if you really see much besides additional muscle-building abilities.

Feltman: And what are the potential downsides? You mentioned that one of the reasons there’s such a boom right now is that research has showed that the connection to prostate cancer is not concerning the way we once thought it was. But what about other issues that can come up when you don’t have low testosterone and you start taking a bunch of testosterone?

Pappas: Right, so if you are taking a testosterone supplement, your body actually shuts down its own testosterone production. There’s this neat little feedback loop that says, “Oh, if the testosterone’s high in the blood, we’re going to just kind of ramp it down.” And a side effect of that is, actually, because testosterone is involved in sperm production...[full transcript]