Kisspeptin in Human Physiology Research: Populations, Endpoints and Findings

Q: What is the difference between kisspeptin-10 and kisspeptin-54?

They are two lengths of the same parent product of the KISS1 gene, which encodes kisspeptins that are the natural ligands of the receptor originally called GPR54 or AXOR12 . Kisspeptin-54 is described as the major circulating isoform in humans and is the peptide used in the assisted-reproduction trials; kisspeptin-10 is the shorter fragment used in most acute physiology studies . Their half-lives and administration protocols differ, so results are not interchangeable.

Q: Has kisspeptin been given to people in clinical studies?

Yes, since 2005, when kisspeptin-54 was reported to stimulate the hypothalamic-pituitary-gonadal axis in human males . Subsequent studies have administered kisspeptin-10 to men , to women , to men with type 2 diabetes , and over 12 days of repeated subcutaneous infusion in healthy men .

Q: What has kisspeptin-54 been tested for in assisted reproduction?

As a trigger for oocyte maturation. A study of 53 women undergoing in vitro fertilisation reported oocyte maturation at every amount tested, fertilisation and embryo transfer in 92% of participants, and clinical pregnancy in 23% . A phase 2 trial in 60 women at high risk of ovarian hyperstimulation syndrome reported oocyte maturation in 95%, live birth in 45% per transfer, and no case of moderate, severe or critical hyperstimulation syndrome .

Q: Why is kisspeptin of interest in reproductive endocrinology?

Because loss-of-function genetics implicate it directly. Inactivating changes in the receptor cause hypogonadotropic hypogonadism , and the gene was characterised as a regulator of puberty in the same period . Administration studies test whether the pathway that genetics identifies can be driven pharmacologically .

Q: Does kisspeptin keep working when administration is continued?

It depends on the pattern. In a randomised single-blinded placebo-controlled study, continuous subcutaneous kisspeptin-10 infusion for 5 days left gonadotropin concentrations similar to vehicle although testosterone remained elevated, whereas daily intermittent 8-hour infusions over 12 days sustained gonadotropin increases (mean luteinising hormone increase +1.68 on day 1 and +1.14 on day 12; P=.003 against vehicle), with the receptor still responsive to a bolus afterwards .

Q: Is kisspeptin approved as a medicine?

No. Kisspeptin-10 and kisspeptin-54 are investigational and are not approved for any indication in the United States or elsewhere. The published work is physiology research and phase 1 and phase 2 clinical studies .

Q: Is kisspeptin used as a diagnostic test?

It has been proposed as one. A 2026 review discusses kisspeptin as a test of hypothalamic dysfunction in pubertal and reproductive disorders , and trials are registered to administer kisspeptin to patients with isolated hypogonadotropic hypogonadism and to quantify gonadotropin-releasing hormone neuronal function in health and disease .

Q: How large are the human kisspeptin studies?

Small. The physiology studies enrol tens of participants — 15 men across three protocols in the 12-day study, with 12 controls . The largest studies are in assisted reproduction: 53 women in the oocyte maturation study and 60 in the phase 2 trial in women at high risk of hyperstimulation .

Kisspeptin-10 and kisspeptin-54 have been administered to people in physiology studies since 2005, and kisspeptin-54 has been tested as an oocyte maturation trigger in assisted reproduction. This article separates the two peptides and sets out what each study measured.

By Elegance Peptides Editorial Team Published September 22, 2026 Updated September 22, 2026

The kisspeptin literature is unusual in this library for two reasons. Its human studies are physiology experiments rather than efficacy trials for most of their history — designed to find out how a signalling system works in people, not whether a product does something for patients. And the pathway was identified from human genetics first, which is a stronger starting point than most compounds here can claim.

It is also a literature about two distinct peptides that share a name. Kisspeptin-10 and kisspeptin-54 are different lengths of the same gene product, with different half-lives and different administration protocols, studied in different settings: kisspeptin-10 predominantly in acute and repeated infusion physiology studies, kisspeptin-54 predominantly in assisted reproduction. Results obtained with one are not results for the other.

This article sets out the record: the genetics and receptor work that motivated it, the human administration studies, the assisted-reproduction trials, the emerging diagnostic use, and the limits of all of it. It describes published research and contains no guidance of any kind on handling any material.

The receptor, and the genetics that made it interesting

In vitro research

The receptor came first and the ligand second. A novel human G protein-coupled receptor designated AXOR12 was reported in 2001 as activated by the peptide product of KiSS-1 ^[1], and in the same year the metastasis suppressor gene KiSS-1 was shown to encode kisspeptins, the natural ligands of the orphan receptor then called GPR54 ^[2].

What turned this into a reproductive-endocrinology programme was human genetics. In 2003, loss of function of the KiSS1-derived peptide receptor was shown to cause hypogonadotropic hypogonadism ^[3], and the gene was characterised as a regulator of puberty ^[4]. A functional receptor-ligand autoregulatory system was subsequently demonstrated in hypothalamic tissue ^[7].

That sequence is the strongest form of target validation available: a pathway identified because people who lack it have a specific, well-defined phenotype. It establishes that the pathway is necessary. It does not establish that driving the pathway pharmacologically produces a clinical benefit, which is what the studies below were built to examine.

What the animal work contributed

Animal research

Animal work supplied the concept that the studies in people were designed to test: that endogenous kisspeptin tone is not merely permissive but an active, continuous input to the reproductive axis. A study in mice reported endogenous kisspeptin tone as a critical excitatory component of spontaneous gonadotropin-releasing hormone activity and of the response to oestradiol ^[11].

The reason this matters for reading the human studies is that it predicts something testable: if kisspeptin tone is a continuous excitatory input, then how the input is patterned in time should determine whether the axis keeps responding. That prediction is precisely what the 12-day human study described below examined.

Human administration studies

Human clinical research

Results from pharmaceutical clinical trials describe the investigational material and populations used in those studies and should not be interpreted as establishing the effects of research-grade materials offered for laboratory use.

First administration in humans. Kisspeptin-54 was reported in 2005 to stimulate the hypothalamic-pituitary-gonadal axis in human males ^[5], and the neuroendocrine physiology of kisspeptin in humans was reviewed shortly afterwards ^[6].

Kisspeptin-10 in men. Kisspeptin-10 was reported as a potent stimulator of luteinising hormone that increases pulse frequency in men ^[8]. Pulse frequency rather than concentration alone is the relevant measure, because the downstream axis responds to the pattern of gonadotropin-releasing hormone release.

Kisspeptin-10 in women. In women, the gonadotrophin response to kisspeptin-10 was shown to be modulated by sex steroid feedback ^[9] — that is, the same administration produces different responses depending on the hormonal background, which constrains how any single study's result can be generalised. Interactions between neurokinin B and kisspeptin in mediating oestrogen feedback have been examined in healthy women ^[12].

A patient population. Kisspeptin-10 was used to probe the pathophysiology of hypogonadism in men with type 2 diabetes, where it stimulated serum testosterone ^[10] — a study using the peptide as an investigative tool rather than as a candidate treatment.

Chronic administration, and the tachyphylaxis question. The most informative single study in this group is recent. Fifteen healthy men were studied across three protocols in a randomised, single-blinded, placebo-controlled design, with 12 men serving as controls: an acute 8-hour subcutaneous infusion across a range of infusion rates from 1.25 to 10.0 nmol/kg/h; continuous subcutaneous infusion at 180 nmol/h for five days; and daily intermittent infusion, 8 hours on and 16 hours off, at 150 nmol/h for 12 days ^[14].

Acute infusions raised luteinising hormone, follicle-stimulating hormone and testosterone in proportion to the infusion rate against vehicle (P<.0001). After five days of continuous infusion, gonadotropin concentrations were similar to vehicle, although testosterone remained elevated. Daily intermittent 8-hour infusions over 12 days sustained gonadotropin increases: mean luteinising hormone change was −0.16 ± 0.19 for vehicle, +1.68 ± 0.25 on day 1 and +1.14 ± 0.33 on day 12 (P=.003 against vehicle). After 12 days, a bolus still produced a gonadotropin rise, indicating the receptor remained functional ^[14].

Why that contrast is the finding. Continuous stimulation of this axis desensitises it; intermittent stimulation does not, over 12 days. This is the same pharmacological principle that governs gonadotropin-releasing hormone analogues, where continuous administration suppresses the axis and pulsatile administration drives it. Any claim about what kisspeptin administration does over time is meaningless without specifying the pattern, and the receptor-functionality check at day 12 is what separates a real answer from an assumption.

Limitations across this group. These are physiology studies with 4 to 15 participants per protocol, hormonal endpoints measured over hours to days, and in most cases healthy volunteers. None has a clinical endpoint. The 12-day study is the longest administration reported and it is 12 days.

Kisspeptin-54 in assisted reproduction

Human clinical research

This is the only setting in which kisspeptin has been tested against an outcome that patients experience directly.

The rationale. People with inactivating changes in kisspeptin signalling are infertile; kisspeptin-54, the major circulating isoform in humans, potently stimulates reproductive hormone secretion; and animal work implicates kisspeptin in generating the luteinising hormone surge required for ovulation. The hypothesis was that kisspeptin-54 could trigger oocyte maturation in in vitro fertilisation ^[18]. Preparatory work had shown that a single injection temporarily increases luteinising hormone pulsatility in healthy women ^[17] and that subcutaneous infusion stimulates gonadotrophin release with a response that correlates with hormonal background ^[21].

The oocyte maturation study. After superovulation with recombinant follicle-stimulating hormone and a gonadotropin-releasing hormone antagonist to prevent premature ovulation, 53 women received a single subcutaneous injection of kisspeptin-54 at one of four amounts (1.6 nmol/kg, n=2; 3.2, n=3; 6.4, n=24; 12.8, n=24). Oocytes were retrieved transvaginally 36 hours later and assessed for maturation, the primary outcome, then fertilised by intracytoplasmic sperm injection with transfer of one or two embryos ^{[18, 19]}.

Oocyte maturation was observed at every amount tested, with the mean number of mature oocytes per patient generally rising with the amount administered. Fertilisation and embryo transfer occurred in 92% (49/53). Biochemical and clinical pregnancy rates were 40% (21/53) and 23% (12/53) ^[18].

The phase 2 trial in women at high risk of hyperstimulation. 60 women at high risk of ovarian hyperstimulation syndrome — a potentially life-threatening complication of in vitro fertilisation — were enrolled in a phase 2, multi-amount, open-label, randomised trial at a single London hospital unit during 2013 to 2014, following a standard recombinant follicle-stimulating hormone and antagonist protocol, with adaptive allocation across four amounts (3.2 nmol/kg, n=5; 6.4, n=20; 9.6, n=15; 12.8, n=20). Oocytes were retrieved at 36 hours. The main outcome was oocyte yield; secondary outcomes were rates of hyperstimulation syndrome and pregnancy ^[20].

Oocyte maturation occurred in 95% of women. The highest oocyte yield, 121%, followed 12.8 nmol/kg — 69% greater than after 3.2 nmol/kg, with a confidence interval from −16% to 153%. Across all amounts, biochemical pregnancy, clinical pregnancy and live birth rates per transfer (n=51) were 63%, 53% and 45%. The highest pregnancy rates followed 9.6 nmol/kg (85%, 77% and 62%). No woman developed moderate, severe or critical ovarian hyperstimulation syndrome ^[20]. The approach has been reviewed as a candidate maturation trigger ^[22].

Limitations. Neither study had a randomised active or placebo comparator against the established trigger; the phase 2 trial randomised between amounts of kisspeptin-54, not against another agent. Both were open-label. The confidence interval on the central yield comparison spans zero. The absence of hyperstimulation syndrome in 60 women is encouraging and cannot exclude an incidence low enough to require a far larger trial to detect. And the pregnancy rates, which are the numbers most often quoted, are secondary outcomes in single-arm-per-amount designs without a comparator.

Diagnostic use and registered trials

Human clinical research

A distinct line of work uses kisspeptin not as a treatment but as a probe. A 2026 review discusses kisspeptin as a test of hypothalamic dysfunction in pubertal and reproductive disorders — administering the peptide and observing the gonadotropin response as a way of establishing whether the hypothalamic component of the axis is intact ^[13].

Two registered trials extend this. One administers kisspeptin subcutaneously to patients with isolated hypogonadotropic hypogonadism ^[15]; another is designed to quantify gonadotropin-releasing hormone neuronal function in health and disease ^[16]. Neither has reported.

A diagnostic application has a lower evidential bar than a therapeutic one in one respect — it needs to discriminate reliably rather than to improve an outcome — and a higher one in another: a test that misclassifies changes what happens to a patient. Neither has been established for kisspeptin in the published record.

What the evidence base does not establish

Any approved use. Neither kisspeptin-10 nor kisspeptin-54 is approved for any indication in the United States or elsewhere. The assisted-reproduction work reached phase 2 ^[20]; nothing in this record is a completed phase 3 programme.

That the two peptides are interchangeable. Kisspeptin-54 is the isoform used in the assisted-reproduction trials ^{[18, 20]} and kisspeptin-10 the fragment used in most physiology studies ^{[8, 14]}. No trial has compared them directly on a shared endpoint.

Anything beyond 12 days of administration. The longest reported administration in humans is 12 days of daily intermittent infusion in 7 men ^[14]. What happens over weeks or months, and whether the axis continues to respond, is unmeasured.

A comparison against established therapy. No trial has randomised kisspeptin-54 against the conventional oocyte maturation trigger, which is the comparison that would determine its place in assisted reproduction.

Effects outside the reproductive axis. Every human endpoint in this record is a reproductive hormone concentration, an oocyte measure or a pregnancy outcome. Claims about other systems have no human trial evidence in this literature.

Anything at all in the absence of a specified administration pattern. The clearest single lesson of the chronic administration study is that continuous and intermittent administration produce opposite gonadotropin results over days ^[14]. A statement about what kisspeptin does that omits the pattern of administration is not a statement about anything these studies measured.

All of the research described in this article is research conducted under registered clinical or laboratory protocols, using investigational material prepared to a regulatory standard and administered under clinical supervision in defined populations. None of it is research into, or evidence about, research-grade material supplied for laboratory use.

Frequently Asked Questions

What is the difference between kisspeptin-10 and kisspeptin-54?

They are two lengths of the same parent product of the KISS1 gene, which encodes kisspeptins that are the natural ligands of the receptor originally called GPR54 or AXOR12 ^{[2, 1]}. Kisspeptin-54 is described as the major circulating isoform in humans ^[18] and is the peptide used in the assisted-reproduction trials; kisspeptin-10 is the shorter fragment used in most acute physiology studies ^[8]. Their half-lives and administration protocols differ, so results are not interchangeable.

Has kisspeptin been given to people in clinical studies?

Yes, since 2005, when kisspeptin-54 was reported to stimulate the hypothalamic-pituitary-gonadal axis in human males ^[5]. Subsequent studies have administered kisspeptin-10 to men ^[8], to women ^[9], to men with type 2 diabetes ^[10], and over 12 days of repeated subcutaneous infusion in healthy men ^[14].

What has kisspeptin-54 been tested for in assisted reproduction?

As a trigger for oocyte maturation. A study of 53 women undergoing in vitro fertilisation reported oocyte maturation at every amount tested, fertilisation and embryo transfer in 92% of participants, and clinical pregnancy in 23% ^{[18, 19]}. A phase 2 trial in 60 women at high risk of ovarian hyperstimulation syndrome reported oocyte maturation in 95%, live birth in 45% per transfer, and no case of moderate, severe or critical hyperstimulation syndrome ^[20].

Why is kisspeptin of interest in reproductive endocrinology?

Because loss-of-function genetics implicate it directly. Inactivating changes in the receptor cause hypogonadotropic hypogonadism ^[3], and the gene was characterised as a regulator of puberty in the same period ^[4]. Administration studies test whether the pathway that genetics identifies can be driven pharmacologically ^[6].

Does kisspeptin keep working when administration is continued?

It depends on the pattern. In a randomised single-blinded placebo-controlled study, continuous subcutaneous kisspeptin-10 infusion for 5 days left gonadotropin concentrations similar to vehicle although testosterone remained elevated, whereas daily intermittent 8-hour infusions over 12 days sustained gonadotropin increases (mean luteinising hormone increase +1.68 on day 1 and +1.14 on day 12; P=.003 against vehicle), with the receptor still responsive to a bolus afterwards ^[14].

Is kisspeptin approved as a medicine?

No. Kisspeptin-10 and kisspeptin-54 are investigational and are not approved for any indication in the United States or elsewhere. The published work is physiology research and phase 1 and phase 2 clinical studies ^{[5, 20, 14]}.

Is kisspeptin used as a diagnostic test?

It has been proposed as one. A 2026 review discusses kisspeptin as a test of hypothalamic dysfunction in pubertal and reproductive disorders ^[13], and trials are registered to administer kisspeptin to patients with isolated hypogonadotropic hypogonadism ^[15] and to quantify gonadotropin-releasing hormone neuronal function in health and disease ^[16].

How large are the human kisspeptin studies?

Small. The physiology studies enrol tens of participants — 15 men across three protocols in the 12-day study, with 12 controls ^[14]. The largest studies are in assisted reproduction: 53 women in the oocyte maturation study ^[18] and 60 in the phase 2 trial in women at high risk of hyperstimulation ^[20].

References

AXOR12, a novel human G protein-coupled receptor, activated by the peptide KiSS-1 The Journal of Biological Chemistry; 2001. PMID 11387329 doi:10.1074/jbc.M102743200
The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54 The Journal of Biological Chemistry; 2001. PMID 11457843 doi:10.1074/jbc.M104847200
Hypogonadotropic hypogonadism due to loss of function of the KiSS1-derived peptide receptor GPR54 Proceedings of the National Academy of Sciences of the United States of America; 2003. PMID 12944565 doi:10.1073/pnas.1834399100
The GPR54 gene as a regulator of puberty The New England Journal of Medicine; 2003. PMID 14573733 doi:10.1056/NEJMoa035322
Kisspeptin-54 stimulates the hypothalamic-pituitary gonadal axis in human males The Journal of Clinical Endocrinology and Metabolism; 2005. PMID 16174713 doi:10.1210/jc.2005-1468
The neuroendocrine physiology of kisspeptin in the human Reviews in Endocrine and Metabolic Disorders; 2007. PMID 17323132 doi:10.1007/s11154-007-9029-1
Expression of a functional g protein-coupled receptor 54-kisspeptin autoregulatory system in hypothalamic gonadotropin-releasing hormone neurons Molecular Endocrinology; 2007. PMID 17698953 doi:10.1210/me.2007-0207
Kisspeptin-10 is a potent stimulator of LH and increases pulse frequency in men The Journal of Clinical Endocrinology and Metabolism; 2011. PMID 21632807 doi:10.1210/jc.2011-0089
Kisspeptin-10 stimulation of gonadotrophin secretion in women is modulated by sex steroid feedback Human Reproduction; 2012. PMID 22956346 doi:10.1093/humrep/des326
Exploring the pathophysiology of hypogonadism in men with type 2 diabetes: kisspeptin-10 stimulates serum testosterone and LH secretion in men with type 2 diabetes and mild biochemical hypogonadism Clinical Endocrinology; 2013. PMID 23153270 doi:10.1111/cen.12103
Endogenous kisspeptin tone is a critical excitatory component of spontaneous GnRH activity and the GnRH response to NPY and CART Neuroendocrinology; 2014. PMID 25011649 doi:10.1159/000365419
Interactions Between Neurokinin B and Kisspeptin in Mediating Estrogen Feedback in Healthy Women The Journal of Clinical Endocrinology and Metabolism; 2016. PMID 27636018 doi:10.1210/jc.2016-2132
Kisspeptin as a test of hypothalamic dysfunction in pubertal and reproductive disorders Andrology; 2026. PMID 39834030 doi:10.1111/andr.13843
Chronic subcutaneous kisspeptin-10 stimulates gonadotropin secretion for 12 days in healthy men European Journal of Endocrinology; 2026. PMID 42549827 doi:10.1093/ejendo/lvag134
Kisspeptin Administration Subcutaneously to Patients With IHH. NCT05896293
Kisspeptin to Quantify GnRH Neuronal Function in Health and Disease. NCT07224490
A single injection of kisspeptin-54 temporarily increases luteinizing hormone pulsatility in healthy women Clinical Endocrinology; 2013. PMID 23452073 doi:10.1111/cen.12179
Kisspeptin-54 triggers egg maturation in women undergoing in vitro fertilization The Journal of Clinical Investigation; 2014. PMID 25036713 doi:10.1172/JCI75730
The Use of the Hormone Kisspeptin in 'in Vitro Fertilisation' (IVF) Treatment. NCT01667406
Efficacy of Kisspeptin-54 to Trigger Oocyte Maturation in Women at High Risk of Ovarian Hyperstimulation Syndrome (OHSS) During In Vitro Fertilization (IVF) Therapy The Journal of Clinical Endocrinology and Metabolism; 2015. PMID 26192876 doi:10.1210/jc.2015-2332
Subcutaneous infusion of kisspeptin-54 stimulates gonadotrophin release in women and the response correlates with basal oestradiol levels Clinical Endocrinology; 2016. PMID 26572695 doi:10.1111/cen.12977
Kisspeptin as a promising oocyte maturation trigger for in vitro fertilisation in humans Gynecological Endocrinology; 2017. PMID 28393578 doi:10.1080/09513590.2017.1309019

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