Gonadorelin vs hCG: Mechanism, Status and Studies
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[Hormones · Comparison]

Gonadorelin vs hCG: how do they differ?

Mechanism · FDA status · Human studies

Short answer: Gonadorelin is a copy of GnRH, the brain hormone that tells the pituitary to release LH and FSH. hCG skips that step and acts like LH directly on the testes.1 hCG is FDA approved for some men with low testosterone from a pituitary or brain cause. Both human gonadorelin products were discontinued, and the only current gonadorelin labels are for animals.23

How do gonadorelin and hCG compare side by side?

hCG from the Novarel and Pregnyl labels; gonadorelin from Drugs@FDA, DailyMed and published human studies.
Gonadorelin (GnRH)hCG (Novarel, Pregnyl)
What it isSynthetic gonadotropin-releasing hormone (GnRH)4Chorionic gonadotropin, which acts on the LH receptor1
Where it actsPituitary, which then releases the body's own LH and FSH4Directly on the testes, in place of LH1
US status for peopleFactrel (approved 1982) and Lutrepulse (approved 1989) are both discontinued25FDA approved; Novarel and Pregnyl have current labels16
Current labelsFive on DailyMed, all veterinary3Approved for undescended testicles in boys, selected hypogonadotropic hypogonadism in males, and ovulation induction6
How it was given in menSmall pulses under the skin from a portable pump; one study also used 500 mcg twice daily47Injection into muscle only, per the label6
Label or study dosingPump: 25 ng/kg every 90 minutes in one 30-man study7Male hypogonadotropic hypogonadism, for example 500 to 1,000 USP units 3 times a week for 3 weeks, then twice a week for 3 weeks6
Half-lifeNo measured value after an injection under the skin in the sources we checkedNot on the Novarel or Pregnyl labels. Dose Track uses about 29 hours, from the Ovidrel label8
SportWADA S2.2.1 in males (named)9WADA S2.2.1 in males (named)9

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

Where does each one act?

The hormone chain runs brain (GnRH) to pituitary (LH and FSH) to testes (testosterone and sperm). Gonadorelin is GnRH, so it works one step down from the brain and needs a working pituitary. In six men whose brain made too little GnRH, small pulses given under the skin by a pump brought LH and FSH into the normal adult range within a week, and testosterone rose from 77 to 520 ng/dL after one month.4

hCG skips the pituitary and acts like LH on the testes.1 Gonadorelin, by contrast, raised both LH and FSH in the studies above.47

Why did the gonadorelin studies use pumps?

The body releases GnRH in pulses, and the human studies copied that. In a 1987 study of 30 men with hypogonadotropic hypogonadism, a pump giving 25 ng/kg every 90 minutes gave better hormone responses, sperm counts and fertility than 500 mcg injected twice a day. With the pump, normal LH and FSH came in 2 to 3 weeks and normal testosterone in 8 to 10 weeks.7

These were men with a GnRH deficiency, not men on TRT. We found no published trial of gonadorelin used to keep the testes active alongside testosterone, and none that compares it with hCG. These are study protocols, not personalized advice; confirm any dosing with your prescriber.

What is the regulatory status of each?

  • hCG: approved and labeled. The label says to inject it into muscle only, and states that hCG has not been shown to be effective for obesity.61
  • Gonadorelin: two human products were approved, Factrel in 1982 and Lutrepulse in 1989, and both are discontinued.25 The gonadorelin labels on DailyMed today are veterinary.3

More detail: the Pregnyl and Novarel dosing schedules, Pregnyl side effects, and the Gonadorelin and hCG (Human Chorionic Gonadotropin) guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
Kisspeptin vs gonadorelin: how do they differ?Signal to the GnRH cells vs GnRH itself hCG vs kisspeptin: how do they differ?Approved LH mimic vs research brain signal hCG vs enclomiphene: how do they differ?Injectable LH mimic vs oral SERM Ovidrel vs Pregnyl: how do recombinant and urinary hCG differ?Prefilled syringe vs mix-it-yourself vial

Frequently asked questions

Is gonadorelin the same as hCG?+
No. Gonadorelin is a copy of GnRH and acts on the pituitary, which then releases LH and FSH. hCG acts like LH directly on the testes.41
Is gonadorelin FDA approved?+
Not as a current human product. Factrel and Lutrepulse were approved in 1982 and 1989 and are both discontinued; the gonadorelin labels on DailyMed today are for animals.253
Has gonadorelin been compared with hCG on TRT?+
Not in a published trial we could find. The human gonadorelin studies treated men with GnRH deficiency, mostly with pumps.47
Are they allowed in sport?+
No. The 2026 WADA List names chorionic gonadotrophin and gonadorelin under S2.2.1 for males.9
Can I track gonadorelin and hCG in Dose Track?+
Yes. Both are built in, with reconstitution math so each dose shows in syringe units, and reminders.

Sources

  1. Novarel (chorionic gonadotropin for injection) prescribing information. DailyMed.
  2. Drugs@FDA: NDA 018123, Factrel (gonadorelin hydrochloride) injection. Original approval September 30, 1982; all strengths discontinued.
  3. DailyMed search for gonadorelin, October 28, 2026: five current labels (Factrel, Cystorelin, Fertagyl, Gonabreed, OvaCyst), all veterinary products.
  4. Hoffman AR, Crowley WF Jr. Induction of puberty in men by long-term pulsatile administration of low-dose gonadotropin-releasing hormone. N Engl J Med. 1982;307:1237-41.
  5. Drugs@FDA: NDA 019687, Lutrepulse kit (gonadorelin acetate) injection. Original approval October 10, 1989; discontinued.
  6. Pregnyl (chorionic gonadotropin) for injection prescribing information. DailyMed, version of December 2025.
  7. Shargil AA. Treatment of idiopathic hypogonadotropic hypogonadism in men with luteinizing hormone-releasing hormone: a comparison of treatment with daily injections and with the pulsatile infusion pump. Fertil Steril. 1987;47:492-501.
  8. Ovidrel (choriogonadotropin alfa) prescribing information, section 12.3. DailyMed.
  9. World Anti-Doping Agency. The 2026 Prohibited List, in force January 1, 2026 (English text as published in the Dutch Treaty Series, Tractatenblad 2026, 25).

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