What it is
Gonadorelin is a man-made copy of a hormone called GnRH. Your brain makes GnRH in short bursts to tell the pituitary gland to release two other hormones, LH and FSH. LH tells the testes to make testosterone. FSH tells them to make sperm. Gonadorelin is a small peptide of 10 amino acids and it is identical to the natural hormone.
When a man takes testosterone (TRT), his brain stops sending the GnRH signal. The pituitary goes quiet, the testes get no instructions, and they shrink and stop making sperm. Gonadorelin is injected to replace that missing signal.
It became popular in TRT clinics after 2020, when the FDA reclassified HCG as a biologic and compounding pharmacies could no longer make it. Clinics needed something else, and gonadorelin was available and cheap. It was not chosen because it worked better than HCG.
Gonadorelin is FDA approved only as a test of pituitary function, under the brand name Factrel. Using it to protect the testes during TRT is off-label. It is available from compounding pharmacies with a prescription.
Gonadorelin is a synthetic decapeptide structurally identical to endogenous gonadotropin-releasing hormone (GnRH). It occupies level one of the hypothalamic-pituitary-gonadal (HPG) axis: hypothalamic GnRH drives pituitary LH and FSH release, LH acts on Leydig cells to drive testosterone synthesis, and FSH acts on Sertoli cells to drive spermatogenesis.
The defining feature of GnRH signalling is pulsatility. Endogenous GnRH is released roughly every 60 to 120 minutes, and this pattern keeps pituitary GnRH receptors responsive. Continuous stimulation desensitises those receptors and suppresses LH and FSH, which is the therapeutic basis of GnRH agonists such as leuprolide in prostate cancer. Pulsatile exposure maintains gonadotropin output; continuous exposure shuts it down. The dosing pattern determines the effect.
Gonadorelin entered mainstream TRT practice after the FDA reclassified HCG as a biologic in 2020 under the CARES Act, removing it from compounding pharmacies. The substitution was regulatory, not evidence-driven; gonadorelin has never been shown superior to HCG for maintaining testicular function on exogenous testosterone.
Regulatory status: FDA approved as a diagnostic agent (Factrel) for evaluating pituitary function; not approved as a therapeutic TRT adjunct; available by prescription through compounding pharmacies and used off-label by TRT clinics.
How it works
Think of the system as a three-step relay. Step one is the brain (GnRH). Step two is the pituitary (LH and FSH). Step three is the testes (testosterone and sperm). Gonadorelin works at step one by copying GnRH and acting directly on the pituitary. HCG, by contrast, skips to step three and acts directly on the testes.
This matters because gonadorelin only works if the pituitary is still able to respond. In a man who has been on testosterone for a long time, the pituitary may be so suppressed that it barely answers the signal. HCG does not have this problem because it bypasses the pituitary.
There is a second challenge. Gonadorelin disappears from the blood very quickly, roughly 2 to 4 minutes. The natural hormone is released in short bursts every 60 to 120 minutes right next to the pituitary. A single injection gives one brief spike and then nothing. Hospital pumps that deliver tiny doses every 90 to 120 minutes copy the natural pattern well and have treated infertility successfully. Once- or twice-daily injections do not copy that pattern, so the results are less certain.
Subcutaneously injected gonadorelin binds GnRH receptors on anterior pituitary gonadotrophs, the same receptors targeted by endogenous GnRH, triggering LH and FSH release. On TRT, exogenous testosterone exerts negative feedback on the hypothalamus, abolishing GnRH secretion; the pituitary then ceases gonadotropin output and the testes cease testosterone and sperm production. Gonadorelin substitutes for the missing hypothalamic signal.
Within the HPG axis, kisspeptin acts at level zero on GnRH neurons, gonadorelin at level one on the pituitary, HCG at level three as an LH mimic on the testes, and enclomiphene by blocking oestrogen feedback at levels one and two. Gonadorelin therefore depends on residual pituitary responsiveness; if deep suppression has downregulated GnRH receptors, the response may be negligible. HCG is not subject to this constraint.
Pharmacokinetics are the central limitation. Gonadorelin has a circulating half-life of approximately 2 to 4 minutes, with a distribution half-life of 2 to 10 minutes and a terminal half-life of 10 to 40 minutes after subcutaneous injection. It is rapidly hydrolysed to peptide fragments and cleared renally. A single injection therefore yields a brief GnRH spike followed by rapid clearance. Pulsatile infusion pumps delivering small doses every 90 to 120 minutes reproduce physiological pulsatility and have induced spermatogenesis in hypogonadotropic hypogonadism. Once- or twice-daily subcutaneous protocols used by TRT clinics do not replicate this pattern, and evidence for their efficacy is correspondingly weaker.
What it does
The main job of gonadorelin on TRT is to keep the testes working. By nudging the pituitary to release LH and FSH, the aim is to prevent testicular shrinkage and keep some ability to make sperm.
Gonadorelin triggers both LH and FSH. HCG only copies LH. FSH is needed to make sperm, so in theory gonadorelin supports both testosterone and sperm production at once. This has been shown with pump studies but not with the daily injections most clinics use.
Because it makes your own pituitary release LH, the resulting signal is closer to natural. HCG stays in the body far longer than natural LH (24 to 36 hours versus 20 to 60 minutes), so it gives a constant push rather than natural bursts.
It is not a testosterone replacement. It could, in theory, raise natural testosterone in a man whose testes work but whose signal is weak, but kisspeptin or enclomiphene have more data for that purpose.
On TRT, gonadorelin is used to sustain gonadotropin output so that Leydig and Sertoli cell activity continues despite hypothalamic suppression, limiting testicular atrophy and preserving fertility potential.
Because it acts at the pituitary, gonadorelin elicits both LH and FSH, whereas HCG mimics LH alone. FSH is required for spermatogenesis, so gonadorelin theoretically supports both the steroidogenic and spermatogenic pathways simultaneously. This advantage is demonstrated in pulsatile GnRH pump studies but unconfirmed with once- or twice-daily subcutaneous injection.
The LH generated is endogenous and released in bursts, giving more physiological downstream signalling than HCG, whose half-life of 24 to 36 hours (versus 20 to 60 minutes for native LH) delivers sustained, non-pulsatile Leydig cell stimulation.
Diagnostically, a 100 mcg IV dose reliably stimulates LH in men with functioning pituitaries; absence of response indicates pituitary dysfunction. Gonadorelin is not a testosterone replacement. In secondary hypogonadism it could in principle raise endogenous testosterone, but kisspeptin and enclomiphene carry more clinical data for that indication.
Benefits
Evidence grades: what the labels mean
- Human trials Supported by randomised or placebo-controlled human trials.
- Limited human data Some human evidence, such as pilot studies, case reports or observational data, but no controlled trials.
- Animal or lab only Shown in animal or cell studies only; not yet tested in people.
- Anecdotal No published studies; based on user reports or theory.
Each grade reflects the strongest published support for that specific claim, not for the compound as a whole.
- Helps keep testicular size and function while on TRTAnecdotal
- Triggers both LH and FSH, so it supports sperm production as well as testosteroneLimited human data
- Uses your own pituitary to release LH, giving a more natural burst pattern than HCGLimited human data
- Available from compounding pharmacies and relatively cheap since HCG became harder to getAnecdotal
- Generally very mild side effectsLimited human data
- Maintains testicular function during exogenous testosterone by restoring a GnRH signal to the pituitaryAnecdotal
- Stimulates both LH and FSH release, supporting steroidogenesis and spermatogenesis; supported by pulsatile pump data in hypogonadotropic hypogonadismLimited human data
- Produces endogenous, burst-pattern LH rather than the sustained non-pulsatile stimulation of HCG (half-life 24 to 36 hours versus 20 to 60 minutes for LH)Limited human data
- Remained available through compounding pharmacies after the 2020 HCG biologic reclassification, at relatively low costAnecdotal
- Well tolerated at standard doses with no serious adverse events reported in published pulsatile studiesLimited human data
What to expect
If you are being tested for pituitary function, LH rises and peaks within 15 to 45 minutes of the injection. For men on TRT using it long term, there is no clear published timeline.
Results vary a lot. Some men, especially younger men new to TRT with a healthy pituitary, report that gonadorelin kept their testicular size normal. Others, especially men on TRT for years, notice no change in size or fertility markers, and some see no rise in LH or FSH on bloodwork.
Most users report gonadorelin works less well than HCG. Many who switched after HCG became hard to get noticed shrinkage that had not happened on HCG. Clinic estimates suggest gonadorelin maintains roughly 50 to 60% of testicular function versus 70 to 80% for HCG, but these figures do not come from published comparisons. Fertility results are mixed. Daily or twice-daily injections are also less convenient than HCG's 2 to 3 times per week.
Side effects are usually mild: injection site irritation (more with twice-daily dosing), mild headache, occasional nausea, and less often lightheadedness, flushing, or fatigue. Check LH, FSH, testosterone, sperm analysis if fertility matters, and testicular size at follow-up.
In diagnostic use in men not on TRT, the LH response peaks 15 to 45 minutes post-injection. For chronic use as a TRT adjunct, the timeline is poorly defined in published research.
Users report highly variable outcomes. Favourable responses cluster in men with intact pituitary function and shorter TRT duration, particularly on twice-daily protocols. Men on long-term TRT frequently report no measurable effect on testicular volume, fertility markers, or LH and FSH on labs. In practice gonadorelin is regarded as inferior to HCG for preventing atrophy; many who switched after the regulatory change experienced atrophy absent on HCG. Clinic estimates place gonadorelin at roughly 50 to 60% preservation of testicular function versus 70 to 80% for HCG, though these are not from published comparative studies. Practitioners frequently describe it as the best available rather than ideal option. Fertility preservation is inconsistent, with some men maintaining conception-adequate counts and others declining despite use.
The evidence base is limited: pulsatile GnRH via pump every 90 to 120 minutes induced testicular growth and spermatogenesis in congenital hypogonadotropic hypogonadism, earlier than cyclical gonadotropin therapy, but no randomised controlled trials address once- or twice-daily subcutaneous gonadorelin during TRT. For HCG, a 2005 study showed 500 IU every other day maintained intratesticular testosterone at baseline while untreated levels fell by 94%; no equivalent gonadorelin study exists.
Tolerability is good. Published literature lists headache, nausea, lightheadedness, injection site reactions, and flushing, typically mild and transient. Injection site reactions predominate with chronic pulsatile administration. Monitor LH, FSH, testosterone, sperm analysis where fertility is the goal, and testicular size.
Reconstitution and dosing
The doses below come from clinical practice, not from published dose-finding studies. The approved diagnostic dose is a single 100 mcg injection, IV or under the skin.
The usual TRT add-on dose is 100 to 200 mcg injected under the skin of the abdomen or thigh, once or twice a day, in the morning or morning and evening, for as long as you stay on TRT. The twice-daily version, 100 mcg in the morning and 100 mcg in the evening, is preferred because two pulses a day come closer to the body's natural bursts than one.
Hospital pumps for hypogonadotropic hypogonadism used 5 to 20 mcg per pulse every 90 to 120 minutes, but this is impractical for most people.
To mix: add 2 mL of bacteriostatic water to a 2 mg vial. Then 10 units on an insulin syringe is 100 mcg and 20 units is 200 mcg.
Get bloodwork for LH and FSH to confirm it is doing anything, plus testosterone, a sperm analysis if fertility is the goal, and a check of testicular size at follow-ups.
Published dosing: 100 mcg IV or subcutaneously as a single diagnostic injection (FDA approved); 5 to 20 mcg per pulse every 90 to 120 minutes via pulsatile pump in hypogonadotropic hypogonadism. No dose-finding studies exist for once- or twice-daily subcutaneous protocols.
Clinical practice pattern as a TRT adjunct: 100 to 200 mcg subcutaneously (abdomen or thigh), once or twice daily, morning or morning and evening, continuously alongside TRT. The twice-daily protocol of 100 mcg morning and 100 mcg evening is preferred on the rationale that two daily pulses better approximate GnRH pulsatility than one, though neither replicates the physiological 60 to 120 minute rhythm given the 2 to 4 minute half-life.
Reconstitution: 2 mg vial in 2 mL bacteriostatic water yields 100 mcg per 10 units on an insulin syringe (200 mcg = 20 units).
Monitoring: LH to confirm pituitary response, FSH (relevant to fertility), testosterone, sperm analysis where fertility is the goal, and clinical assessment of testicular size. Do not combine with GnRH agonists such as leuprolide or GnRH antagonists (pharmacological conflict). Some practitioners pair low-dose gonadorelin with low-dose HCG to target pituitary and testes simultaneously, without published support. Combining with enclomiphene during TRT is pharmacologically incoherent because the axis is actively suppressed.
Standard (once or twice daily), 2 mg vial
Mix with 2 mL (200 units) of bacteriostatic water.
1 mg/mL · 10 mcg per unit
Cycle: Continuous alongside TRT · Frequency: Once or twice daily, morning or morning and evening
| When | Dose | Draw | How often |
|---|---|---|---|
| Starting | 100 mcg | 10 units | once or twice daily |
| Full | 200 mcg | 20 units | once or twice daily |
Standard (twice daily), 2 mg vial
Mix with 2 mL (200 units) of bacteriostatic water.
1 mg/mL · 10 mcg per unit
Cycle: Continuous alongside TRT · Frequency: Twice daily, morning and evening
| When | Dose | Draw | How often |
|---|---|---|---|
| Morning | 100 mcg | 10 units | 1 of 2 daily doses |
| Evening | 100 mcg | 10 units | 2 of 2 daily doses |
2 mg in 2 mL is 1 mg/mL, or 10 mcg per unit. Draw 10 units (0.1 mL) for 100 mcg.
Who should avoid it
- Anyone with a known allergy to GnRH or gonadorelin.
- Men with primary hypogonadism, where the testes themselves have failed. Gonadorelin works on the pituitary, so it cannot fix a problem further down the chain.
- People with pituitary tumours or other conditions that could be made worse by stimulating LH and FSH.
- People with hormone-sensitive cancers such as prostate cancer or breast cancer.
- Anyone taking a GnRH agonist such as leuprolide or a GnRH antagonist. These drugs pull in the opposite direction.
- Use extra caution if you are pregnant or breastfeeding. There is no safety data for this situation.
- Use extra caution if you have significant pituitary damage or dysfunction, because the pituitary may not respond.
- Known hypersensitivity to GnRH or gonadorelin.
- Primary hypogonadism (testicular failure). The lesion is downstream of the pituitary, so GnRH receptor stimulation of gonadotrophs cannot restore Leydig or Sertoli cell output.
- Pituitary tumours or conditions that could be exacerbated by gonadotropin stimulation.
- Hormone-sensitive malignancies, including prostate cancer and breast cancer.
- Concurrent GnRH agonists (leuprolide) or GnRH antagonists. Continuous agonism desensitises the GnRH receptor and suppresses LH and FSH, the opposite of the intended pulsatile effect; antagonists block the receptor outright.
- Caution in pregnancy or breastfeeding; no safety data exists in this context.
- Caution with significant pituitary dysfunction or damage, where downregulated GnRH receptors may not mount a meaningful LH or FSH response.
Side effects
- Headache, usually mild and short-lived.
- Nausea, occasional and mild.
- Lightheadedness.
- Redness, soreness or irritation where the needle goes in. This is more noticeable with twice-daily injections.
- Warmth or flushing.
- Tiredness (less common).
- Most users report few or no side effects. In published studies, no serious problems have been reported with subcutaneous pulsatile gonadorelin.
- Headache, typically mild and transient.
- Nausea.
- Lightheadedness.
- Injection site reactions; the most commonly reported issue with chronic pulsatile pump administration, and more prominent with twice-daily subcutaneous dosing.
- Flushing or warmth.
- Fatigue (less common in user reports).
- At the 100 mcg diagnostic dose, adverse effects are minimal. No serious adverse events have been reported with subcutaneous pulsatile gonadorelin in published studies.
What the evidence shows
The strongest evidence for gonadorelin comes from a different situation than the one most TRT users are in. In men born with a condition where the brain does not send the GnRH signal, small pumps that deliver gonadorelin every 90 to 120 minutes have grown the testes and started sperm production. One study (Liu et al., 2019) found that this pulsatile pump approach started sperm production earlier than cyclical gonadotropin therapy.
Gonadorelin is also approved by the FDA as a diagnostic test under the brand name Factrel. A single 100 mcg dose reliably makes a healthy pituitary release LH, with the peak at 15 to 45 minutes. If nothing happens, that points to a pituitary problem.
What is missing is evidence for how gonadorelin is actually used alongside TRT: one or two injections a day. No published randomised trial has tested whether this keeps the testes working during TRT. The support for it comes from clinic observations that have not been peer reviewed.
By comparison, HCG has a landmark study (Coviello et al., 2005) showing that 500 IU every other day kept testosterone inside the testes at normal levels, while without HCG it fell by 94%. A 2018 review (Patel et al., 2018) summarised the case for HCG in men. No equivalent study exists for gonadorelin.
In short: pulsatile pump gonadorelin is well supported for hypogonadotropic hypogonadism. Once- or twice-daily injections as an HCG replacement rest mainly on clinical practice, not trials.
Published evidence for gonadorelin as a TRT adjunct is limited. The supportive literature comes almost entirely from pulsatile GnRH administration in hypogonadotropic hypogonadism, a distinct clinical scenario in which the hypothalamic signal is absent rather than suppressed by exogenous androgen.
Liu et al. (2019) reported that a pulsatile gonadorelin pump delivering pulses every 90 to 120 minutes induced testicular growth and spermatogenesis in men with congenital hypogonadotropic hypogonadism, and did so earlier than cyclical gonadotropin therapy. Earlier work by Hoffman and Crowley (1982) demonstrated induction of puberty with long-term pulsatile low-dose GnRH, and Crowley and McArthur (1980) simulated a normal menstrual cycle in Kallmann syndrome by pulsatile LHRH. Studied pump doses were 5 to 20 mcg per pulse.
At the FDA-approved diagnostic dose of 100 mcg IV or subcutaneously, gonadorelin reliably stimulates LH release in men with intact gonadotroph function, peaking at 15 to 45 minutes. Absent response indicates pituitary dysfunction.
No published randomised controlled trials address once- or twice-daily subcutaneous gonadorelin for maintenance of testicular function during TRT, and no dose-finding studies exist for these protocols. Given a plasma half-life of approximately 2 to 4 minutes (distribution half-life 2 to 10 minutes, terminal 10 to 40 minutes after subcutaneous injection), a single daily injection produces a brief GnRH receptor pulse followed by roughly 24 hours without signal, which does not replicate the endogenous 60 to 120 minute pulsatility that maintains gonadotroph responsiveness.
The comparator, HCG, has direct evidence: Coviello et al. (2005) showed 500 IU every other day maintained intratesticular testosterone at baseline during testosterone-induced gonadotropin suppression, whereas intratesticular testosterone fell by 94% without it. Patel et al. (2018) reviewed indications for HCG in hypogonadal men. No equivalent intratesticular testosterone data exist for gonadorelin.
User reports
From public forums
Reports vary a lot. Some men say gonadorelin kept their testicle size normal on TRT, especially younger men who were new to testosterone and had a healthy pituitary. Twice-daily dosing is more often linked with good results than once-daily. Some clinics say it keeps fertility markers adequate in a subset of patients. Low cost is often mentioned as a plus.
The most common complaint is that it does not work as well as HCG. Many men who switched from HCG to gonadorelin after 2020 noticed their testicles shrank in a way that had not happened on HCG. Fertility results are mixed: some kept sperm counts good enough for conception, others saw counts fall. Some users see no change in LH or FSH on blood tests. Daily or twice-daily injections are also seen as a hassle compared with HCG's 2 to 3 times per week.
Estimates from clinics and forums put gonadorelin at roughly 50 to 60% of testicular function maintained versus 70 to 80% for HCG, but these figures are not from published studies. Clinic practitioners often describe it as "better than nothing" rather than ideal.
User reports are heterogeneous. Favourable outcomes cluster among men with shorter TRT duration and presumably intact gonadotroph responsiveness, and among those using twice-daily protocols. Some clinic-generated observations suggest adequate maintenance of fertility markers in a subset of patients. Cost relative to HCG is a consistently cited advantage.
The dominant negative report is inferior preservation of testicular volume compared with HCG. Men who transitioned from HCG to gonadorelin following the 2020 biologic reclassification frequently describe noticeable atrophy that had not occurred on HCG. Fertility maintenance is inconsistent, with some users reporting declining sperm counts despite use. Some users report no detectable change in LH or FSH on labs, consistent with either receptor downregulation under exogenous androgen or inadequate pulse frequency. The daily or twice-daily injection burden compares unfavourably with HCG's 2 to 3 times per week schedule.
Clinic and forum estimates of roughly 50 to 60% testicular function maintained for gonadorelin versus 70 to 80% for HCG are not derived from published comparative studies. Several TRT clinic practitioners have publicly characterised gonadorelin as the best available substitute rather than the ideal one.
User reports are individual experiences submitted by site visitors. They are not medical advice, are not verified for accuracy, and do not reflect Amino Reference's views. Read the evidence section above and talk to a clinician. Full disclaimer.
Stacking
- TRT (exogenous testosterone)
This is the main use. Gonadorelin is taken once or twice daily alongside testosterone to help keep the testes active and preserve some fertility while the body's own signal is switched off.
Primary use case. Exogenous testosterone suppresses hypothalamic GnRH via negative feedback; gonadorelin supplies the missing pituitary signal to sustain LH and FSH output. Dosed daily or twice daily alongside the standard TRT schedule, continuously.
Some practitioners combine low doses of both. Gonadorelin gives the FSH signal from the pituitary, while HCG acts directly on the testes. No published research supports this combination.
Low-dose gonadorelin for gonadotroph-driven FSH release combined with low-dose HCG for direct LH-receptor stimulation of Leydig cells targets the pituitary and testes simultaneously. No published research supports this specific combination protocol.
No known interaction. They work on completely different systems. GH peptides need to be taken fasted; gonadorelin does not, so there is no timing clash.
No interaction concerns. GH secretagogues act on GHRH and ghrelin receptor systems, independent of the GnRH axis. GH peptides require fasting; gonadorelin does not, so no timing conflicts arise.
No known interaction. The two do entirely different jobs.
No interaction concerns. Completely independent mechanisms.
No known interaction. The two do entirely different jobs.
No interaction concerns. Completely independent mechanisms.
- Enclomiphene (not recommended during TRT)
This pairing does not make sense on TRT. Enclomiphene tries to lift the brain's own signal, but testosterone is already suppressing it. Enclomiphene is for men not on TRT, or before starting it.
Pharmacologically incoherent during TRT. Enclomiphene blocks oestrogen negative feedback at the hypothalamus and pituitary to raise GnRH and LH; exogenous testosterone is actively suppressing that axis, so stacking both attempts to stimulate a suppressed system. Enclomiphene is a standalone or pre-TRT intervention, not a TRT adjunct.
Common questions
Is gonadorelin as good as HCG for preventing testicular atrophy?
Probably not. HCG acts straight on the testes. Gonadorelin needs the pituitary to respond, and on TRT the pituitary may be partly shut down. Users and clinics generally find HCG more effective, but gonadorelin is the most widely available alternative.
Probably not. HCG bypasses the pituitary and stimulates Leydig cells directly via the LH receptor. Gonadorelin depends on gonadotroph GnRH receptor responsiveness, which may be blunted under exogenous androgen suppression. Clinical observation and user reports favour HCG; gonadorelin is the best widely available alternative since HCG became harder to obtain.
Why did clinics switch from HCG to gonadorelin?
In 2020 the FDA reclassified HCG as a biologic under the CARES Act, so compounding pharmacies could no longer make it. Clinics moved to gonadorelin because it was available, not because it was shown to work better.
The 2020 FDA reclassification of HCG as a biologic under the CARES Act removed it from compounding pharmacies. The substitution was regulatory-driven, not evidence-based; gonadorelin was never shown to be superior or equivalent for maintaining testicular function during TRT.
Does gonadorelin preserve fertility on TRT?
It may help, but the evidence is weaker than for HCG. Gonadorelin triggers both LH and FSH, which supports both testosterone and sperm production. Results depend on how well the pituitary responds and vary widely from person to person.
Possibly. Gonadorelin stimulates both LH and FSH release, supporting Leydig cell steroidogenesis and Sertoli cell spermatogenesis. The FSH advantage over HCG is supported by pulsatile pump data but not confirmed with once- or twice-daily subcutaneous protocols. Efficacy depends on residual gonadotroph responsiveness and varies widely.
Why does dosing frequency matter so much?
The body releases GnRH in pulses every 60 to 120 minutes, and that rhythm keeps the pituitary responsive. Gonadorelin lasts only about 2 to 4 minutes in the blood, so one daily shot gives a short burst and then nothing for 24 hours. Twice daily is better but still not the natural pattern. A pump every 90 minutes is the gold standard but impractical for most people.
Endogenous GnRH pulses every 60 to 120 minutes maintain gonadotroph GnRH receptor sensitivity; continuous exposure desensitises the receptor, the basis of GnRH agonist suppression therapy. With a 2 to 4 minute half-life, a single daily injection yields a brief spike followed by 24 hours of no signal. Twice-daily dosing approximates pulsatility somewhat better; pulsatile pump delivery every 90 minutes is the gold standard but impractical.
Can gonadorelin be used instead of TRT?
It is not a testosterone replacement. It tells the pituitary to release LH and FSH, which then tell the testes to make testosterone. If the testes work (secondary hypogonadism), it could in theory raise natural testosterone, but kisspeptin or enclomiphene have more clinical data for that job.
Gonadorelin is not a testosterone replacement. In secondary hypogonadism with functional testes it could theoretically raise endogenous testosterone via LH release, but kisspeptin (acting upstream on GnRH neurons) or enclomiphene (removing oestrogen negative feedback) have more clinical data supporting that use.
What should be checked on blood tests while using gonadorelin?
LH, to confirm the pituitary is responding; FSH, which matters for fertility; testosterone; a sperm analysis if fertility is the goal; and testicle size at follow-up visits.
LH to confirm gonadotroph response; FSH to confirm Sertoli cell support for spermatogenesis; testosterone (intratesticular production if measurable); semen analysis if fertility is the goal; and clinical assessment of testicular volume at follow-up.
Is HCG available again?
Availability has gone up and down since the reclassification. Some compounding pharmacies have special permission to make it, and some commercial HCG products are still sold. Check with a TRT provider for current local availability.
HCG availability has fluctuated since the biologic reclassification. Some compounding pharmacies have obtained special permissions, and some commercial HCG products remain available. Current availability depends on jurisdiction and provider.
References
- Liu Z, et al. The Pulsatile Gonadorelin Pump Induces Earlier Spermatogenesis Than Cyclical Gonadotropin Therapy in Congenital Hypogonadotropic Hypogonadism Men. Frontiers in Endocrinology. 2019;10:445.
- Coviello AD, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. Journal of Clinical Endocrinology and Metabolism. 2005;90(5):2595-2602.
- Patel DP, et al. Indications for the use of human chorionic gonadotropic hormone for the management of infertility in hypogonadal men. Translational Andrology and Urology. 2018;7(Suppl 3):S348-S355.
- Conn PM, Crowley WF Jr. GnRH agonists: gonadorelin, leuprolide and nafarelin. Obstetrical and Gynecological Survey. 1992;47(3):172-173.
- Hoffman AR, Crowley WF Jr. Induction of puberty in men by long-term pulsatile administration of low-dose gonadotropin-releasing hormone. New England Journal of Medicine. 1982;307(20):1237-1241.
- Crowley WF Jr, McArthur JW. Simulation of the normal menstrual cycle in Kallman's syndrome by pulsatile administration of luteinizing hormone-releasing hormone (LHRH). Journal of Clinical Endocrinology and Metabolism. 1980;51(1):173-175.
- DrugBank. Gonadorelin: Uses, Interactions, Mechanism of Action.
This entry was written from additional reference material. Units are recomputed from the stated protocol.