# Does kisspeptin raise testosterone? > Does kisspeptin raise testosterone? | Real TRT — The testosterone experiments at Real TRT: healthy men, measured LH and testosterone responses, and the revealing difference with impaired GnRH function. **The human experiments** Yes, in the human experiments described here. The population and the conditions give that answer its meaning. ## Healthy men in the early study In the [2005 kisspeptin-54 experiment](https://pubmed.ncbi.nlm.nih.gov/16174713/), the participants were healthy men, and the group contained six people. During the intravenous study, mean 90-minute LH was 10.8 +/- 1.5 U/L with kisspeptin-54, compared with 4.2 +/- 0.5 U/L on saline. FSH and testosterone rose by smaller amounts. The hormonal response was observable, and the comparison gave it a reference point. The ordering matters to me: LH, then the smaller responses in FSH and testosterone. A summary centred entirely on testosterone would hide the most prominent measured change. I give the experiment credit for demonstrating activity in the human reproductive system, with the modest scale of the study still attached. There is also a difference between finding an effect in healthy men and finding a useful treatment for a person with a particular hormonal disorder. That difference is the next problem to solve. Six healthy participants cannot carry the whole clinical argument, however striking the laboratory response looks. ![Gloved hands positioning a clear assay plate in a laboratory reader on an olive mat](images/testosterone-assay.webp) *An imagined assay scene: the subject here is a measured hormonal response, rather than a portrait of anyone in the studies.* ## Kisspeptin-10 and the pulse measurements The [2011 kisspeptin-10 study in healthy men](https://pubmed.ncbi.nlm.nih.gov/21632807/) provides a more detailed look at the response. In its bolus experiment, LH rose from 4.1 to 12.4 IU/L at 30 min. In an infusion condition, mean LH rose from 5.2 to 14.1 IU/L and LH pulse frequency increased from 0.7 to 1.0 pulses/h. A higher-rate infusion condition raised serum testosterone from 16.6 to 24.0 nmol/L. These are findings from the study's different experimental conditions. The pulse measurement is particularly satisfying. It asks about the pattern of hormone release as well as the amount. An account that preserves that distinction has more to offer me than a single impressive before-and-after figure. The underlying work has an animal component too: [experiments in mice and sheep](https://pubmed.ncbi.nlm.nih.gov/15665093/) connected kisspeptin's receptor to GnRH release and the associated LH response. Together, these papers describe a chain of observations. They give the mechanism substance while leaving the human results anchored to the men actually studied. ## Impaired GnRH function A useful complication appears in [people with abiding idiopathic hypogonadotropic hypogonadism](https://pubmed.ncbi.nlm.nih.gov/25226293/). In that cohort, a kisspeptin challenge failed to produce the GnRH-mediated LH response reliably seen in healthy men. The condition's long name refers to impaired reproductive hormone signalling; the experiment used kisspeptin to probe the functional capacity of the GnRH neuronal network. Those observations forced a more precise question on me. I began with whether the molecule could raise a hormone; the sharper question is whether the relevant signalling machinery can respond in the population under discussion. An unresponsive group is scientifically valuable. It makes the apparent simplicity of the healthy-men experiment harder to overextend. An account of the participants' underlying condition would make a broader testosterone claim more convincing. There are several distinct observations to explain. ## Responsiveness after reversal The [men studied after reversal of congenital idiopathic hypogonadotropic hypogonadism](https://pubmed.ncbi.nlm.nih.gov/27214398/) add a different observation. In those men, kisspeptin responsiveness tracked the presence of endogenous LH pulses. The ability to respond accompanied reactivation of the reproductive system. Earlier [human genetics had linked loss of receptor function to failed or incomplete puberty](https://pubmed.ncbi.nlm.nih.gov/14573733/), with low LH and FSH; the investigators reproduced the phenotype in mice. That history makes the later probe experiments more revealing. The receptor's importance had a genetic basis, and the challenge studies then asked about functional responsiveness in particular groups. I hesitate to compress that sequence into a general booster claim. The experimental problem concerns the condition of the signalling system, and the observations differ with the group being examined. A response in healthy men, an absent response in abiding disease and responsiveness after reversal are a more informative set of findings than an isolated testosterone value. The distinction also explains why the [repeated-exposure experiments](/repeated-signal) deserve their own discussion. They examine another way in which the next response can differ from the first. --- At Real TRT I scrutinise published research on kisspeptin and testosterone; this is an editorial site rather than a treatment business, and none of it is medical advice.