Gonadorelin

gonadotropin-releasing hormone, GnRH, LHRH (luteinising hormone-releasing hormone), gonadorelin acetate/hydrochloride, Factrel, Lutrepulse (pump), Fertagyl and Cystorelin (veterinary), HRF

Longevity & cellular

Awaiting medical reviewEN ES DE FR PT ZH+ Follow for updates

Note on this profile. Gonadorelin is the synthetic copy of a natural hormone and is an approved prescription medicine in several countries for diagnostic testing and, via pump, for fertility treatment; in the US the brand Factrel was discontinued, and gonadorelin is now mainly available through compounding pharmacies, most often prescribed alongside testosterone therapy. That use is off-label. Community use without prescription is unapproved. This page explains the published science.

Summary

Class: Synthetic decapeptide (10 amino acids) identical to native human GnRH; agonist at the GnRH receptor on pituitary gonadotroph cells
Mechanism: Signals the pituitary to release LH and FSH in a pulse; given in pulses it drives the gonads, given continuously it shuts them down
Routes studied: Intravenous and subcutaneous bolus (diagnostic test); subcutaneous or IV pulsatile pump (fertility); intranasal (older studies); subcutaneous 2–3 times weekly (compounded use with TRT)
Dose range reported: Diagnostic test: 100 µg IV or subcutaneous single dose (adults; 2.5 µg/kg children, max 100 µg). Pulsatile pump: 5–20 µg per pulse every 60–120 minutes (Lutrepulse label and studies; some protocols up to 25 µg). Compounded with TRT: commonly 100–200 µg subcutaneous 2–3 times weekly, or 50–100 µg daily; community figures similar. Approved label doses are the diagnostic and pump doses only
Half-life: 2–10 minutes in plasma (very short; cleared by peptidases in the pituitary, kidney and liver)
Storage: Lyophilised: refrigerate or room temperature per label, protect from light. Reconstituted: refrigerate; use within the period on the label (compounded products typically 28 days or less)
Regulatory status: Approved for diagnostic use (and pulsatile fertility therapy) in several countries; US branded product discontinued, compounded gonadorelin available by prescription; not approved for use with TRT anywhere

Doses are as reported in studies or by the community — never recommendations.

1What it is

Gonadorelin is the exact synthetic copy of GnRH, the 10-amino-acid hormone the hypothalamus releases in pulses roughly every 1–2 hours. Its structure was worked out in 1971 by Andrew Schally and Roger Guillemin, who shared the 1977 Nobel Prize for it. GnRH travels a few millimetres down a dedicated blood supply to the pituitary and tells it to release LH and FSH; those in turn stimulate testosterone and sperm production in men and oestrogen production and ovulation in women.

Because native GnRH lasts only minutes, the pharmaceutical industry mostly built on it rather than selling it as-is: long-acting (leuprolide, triptorelin, goserelin) that paradoxically suppress the axis, and antagonists (cetrorelix, degarelix, elagolix) that block it. Gonadorelin itself was approved as Factrel (US, 1982) for testing pituitary function and as Lutrepulse / Lutrelef for pulsatile fertility treatment. After the US brand lapsed, gonadorelin came back into prescribing through compounding pharmacies as a replacement for HCG in men on testosterone therapy, especially after 2020 when the US tightened rules on compounded HCG. That is where most current community discussion comes from.

2How it's thought to work

Pulsatile = stimulate. Each pulse of GnRH binds the pituitary GnRH receptor and releases a pulse of LH (and FSH). The pituitary needs the gaps between pulses to re-sensitise.

Continuous = suppress. Sustained receptor occupation down-regulates the receptors, and within 1–3 weeks LH, FSH and sex steroids fall to castrate levels — the basis of leuprolide therapy for prostate cancer and endometriosis. Gonadorelin is too short-acting to do this at usual intermittent doses.

Under testosterone therapy. exogenous testosterone switches off the body's own GnRH, so LH falls and the testes shrink and stop making testosterone and sperm. The rationale for adding gonadorelin is that intermittent doses mimic the lost pulses and keep the pituitary–testis link working. Whether a dose every 2–3 days (not every 2 hours) achieves this is the open question discussed below.

GnRH itself: pulses make the pituitary release LH and FSH (top); a continuous supply switches the response off (bottom).Schematic — not to scale

3What the research shows

Graded A (long-established)

Diagnostic GnRH stimulation test

A 100 µg dose produces a measurable LH and FSH rise within 15–45 minutes in people with a normal pituitary; a flat response points to pituitary failure and helps distinguish constitutional delayed puberty from hypogonadotropic hypogonadism, and to confirm central precocious puberty (Roth 1972, J Clin Endocrinol Metab; many subsequent studies). Partly superseded by leuprolide stimulation tests where gonadorelin is unavailable. [2]

Graded A/B

Pulsatile GnRH for hypothalamic amenorrhoea and anovulation

Portable pumps delivering GnRH every 60–120 minutes restore ovulation in most women whose problem is hypothalamic (not ovarian), with ovulation rates around 80–90% per cycle and good pregnancy rates in cohorts and small comparative trials (Leyendecker 1980, Arch Gynecol; Martin 1993, J Clin Endocrinol Metab; Christin-Maitre 2007). Lower multiple-pregnancy and hyperstimulation rates than gonadotropin injections. [3][4]

Pulsatile GnRH for male hypogonadotropic hypogonadism

Pulsatile GnRH restores testosterone and induces sperm production in men whose pituitary is intact (e.g. Kallmann syndrome), with outcomes comparable to HCG/FSH injections in cohort studies (Pitteloud 2002, J Clin Endocrinol Metab; Liu 1988). Pumps are cumbersome and rarely used now. [5]

Graded — / B (indirect)

Preventing testicular shrinkage and preserving fertility during testosterone therapy

This is the main current use and it has no dedicated controlled trial. The supporting evidence is indirect: pulsatile GnRH works in hypogonadotropic men (above), and HCG co-administration preserves intratesticular testosterone and sperm production in men on TRT (Coviello 2005; Hsieh 2013 — see HCG profile). Infrequent gonadorelin bolus dosing (2–3 times weekly) has not been shown to maintain LH or testicular volume, and given a of minutes a single bolus produces one LH pulse that lasts about an hour. Clinician case reports and community reports are mixed. Treat as "biologically plausible, untested".

Intranasal gonadorelin

Older studies showed nasal absorption and LH responses at milligram doses; not pursued.

4Reported side effects and interactions

Literature-reported

Literature (label and trials). generally well tolerated. Headache, flushing, nausea, abdominal discomfort, light-headedness, injection-site reactions (redness, swelling, pain — including induration with pump catheters), and rare hypersensitivity including anaphylaxis (reported with Factrel). With pulsatile therapy: multiple pregnancy risk (lower than with gonadotropins) and occasional ovarian hyperstimulation. Antibody formation to GnRH has been reported with long-term pump use.

Community-reported

mild headache, flushing, transient nausea; some men report maintained testicular size and libido on TRT, others report no difference; acne or mood swings attributed to fluctuating oestradiol in a minority.

Theoretical. if dosing were frequent and sustained enough it would suppress rather than stimulate (the leuprolide effect); this is unlikely at common schedules but is the mechanism behind the paradoxical reports. Stimulating the axis is undesirable in hormone-sensitive cancers. Pituitary apoplexy has been reported with GnRH in people with pituitary adenomas; a theoretical class concern for anyone with a known adenoma.

Interactions. androgens, oestrogens, progestins, glucocorticoids and dopamine antagonists blunt the LH response and invalidate the diagnostic test; spironolactone, levodopa and digoxin can alter responses (label). Phenothiazines raise prolactin and blunt gonadotropin release.

Markers researchers commonly monitor

Marker	Why it's watched
LH and FSH	the direct effect; a sample 30–45 minutes after a dose shows whether the pituitary responded, which is the core of the diagnostic test.
Total testosterone and oestradiol	downstream effect; on TRT these mostly reflect the testosterone dose, so a change attributable to gonadorelin is hard to isolate.
Testicular volume (orchidometer or ultrasound)	the practical endpoint for the "maintain testicular size on TRT" rationale.
Semen analysis	if fertility preservation is the aim.
Prolactin	high prolactin suppresses the axis and alters responses.
Haematocrit and PSA	standard whenever testosterone is in the protocol.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Compounded gonadorelin is usually supplied as 2 mg or 10 mg vials, or pre-mixed solution, and with to a concentration that makes 100–200 µg a convenient volume. Pump cassettes are prepared by the pharmacy. Reconstituted solutions degrade over weeks; follow the pharmacy's beyond-use date.

Open in calculator, pre-loaded →

6Commonly studied alongside

Testosterone replacement therapy (the main current context); HCG (the alternative and historical standard for the same purpose); enclomiphene or clomiphene (raise LH by a different mechanism); kisspeptin (one step upstream); FSH (added to pulsatile GnRH or HCG when sperm production is the goal).

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Factrel (gonadorelin HCl) approved 1982 for diagnostic use; brand discontinued. Lutrepulse (pulsatile) discontinued. Gonadorelin acetate is on FDA's list of bulk substances that may be used in 503A compounding (Category 1) †, so it is available by prescription through compounding pharmacies; use with TRT is off-label
European Union	Approved in several member states for the GnRH stimulation test (e.g. gonadorelin injection products in Germany) and pulsatile therapy (Lutrelef) in some †
United Kingdom	HRF (gonadorelin) was licensed for diagnostic use; availability intermittent, often via specialist import †
Australia	Prescription-only (Schedule 4); HRF registered for diagnostic use historically †
South Africa	Registered diagnostic product status uncertain †
Sport (WADA)	Prohibited for men under S2 (peptide hormones and releasing factors — "GnRH and its analogues are prohibited in males only")

8Open questions

Does 2–3 times weekly bolus gonadorelin do anything measurable in men on TRT? No controlled trial exists.
Equivalence to HCG for testicular volume and intratesticular testosterone.
Stability and potency of compounded gonadorelin over the dispensed period.
Whether more frequent low-dose schedules (closer to physiology) would help or suppress.

9References

1Schally AV et al. (1971). Gonadotropin-releasing hormone: one polypeptide regulates secretion of luteinizing and follicle-stimulating hormones. Science. PubMed · DOI
2Roth JC et al. (1972). FSH and LH response to luteinizing hormone-releasing factor in prepubertal and pubertal children, adult males and patients with hypogonadotropic and hypergonadotropic hypogonadism. J Clin Endocrinol Metab. DOI
3Leyendecker G, Wildt L, Hansmann M (1980). Pregnancies following chronic intermittent (pulsatile) administration of Gn-RH by means of a portable pump ("Zyklomat") — a new approach to the treatment of infertility in hypothalamic amenorrhea. J Clin Endocrinol Metab. PubMed · DOI
4Martin KA et al. (1993). Clinical review 15: management of ovulatory disorders with pulsatile gonadotropin-releasing hormone. J Clin Endocrinol Metab. PubMed
5Pitteloud N et al. (2002). Predictors of outcome of long-term GnRH therapy in men with idiopathic hypogonadotropic hypogonadism. J Clin Endocrinol Metab. PubMed · DOI
6Belchetz PE et al. (1978). Hypophysial responses to continuous and intermittent delivery of hypothalamic gonadotropin-releasing hormone. Science. PubMed · DOI
7Factrel (gonadorelin hydrochloride) US prescribing information (historical label). PubMed
8FDA. Bulk drug substances nominated for use in compounding under section 503A — gonadorelin acetate entry [verify category]. PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

forum threads →

community protocols include this →

Threads and protocols are visible to members. Joining is free.

Self-reported side effects Phase 2

Not enough data yet. 0 of the 50 members needed have logged this compound for 4+ weeks. We don't show anything below 50, so no one can be identified.

11Page history

25 Oct 2026Profile published — awaiting medical review

Licensed CC BY-NC-SA 4.0. Found an error? Report it · Editorial standards — corrections are logged here.