HCG (Human Chorionic Gonadotropin)

Research Reagent · Laboratory Use Only

What does research show about the biological mechanisms of human chorionic gonadotropin (HCG)?

Research indicates HCG is a glycoprotein hormone that binds luteinizing hormone receptors, stimulating gonadal steroidogenesis. Studies published in PubMed demonstrate roles in luteal phase support, testosterone biosynthesis regulation, and trophoblast development. Preclinical models also explore HCG signalling in non-reproductive tissues, including thyroid and immune modulation pathways.

Scientific AbstractPMID 42044038 · 2015

Low circulating testosterone in physically stressed populations is frequently interpreted as evidence of hypogonadism or intrinsic gonadal dysfunction. However, convergent data from military field studies, endurance athletes, and competitive stress models demonstrate that testosterone suppression during sustained stress is commonly a centrally mediated, reversible adaptation rather than intrinsic testicular failure. Severe energy deficit, sleep disruption, and uncontrollable psychogenic stress suppress hypothalamic gonadotropin-releasing hormone and luteinizing hormone pulsatility, reduce testicular androgen production, and frequently increase sex hormone-binding globulin (SHBG), thereby disproportionately lowering free testosterone.

Human chorionic gonadotropin stimulation studies confirm preserved Leydig cell responsiveness under these conditions, supporting hypothalamic-pituitary inhibition as the dominant mechanism. In contrast, high mechanical loading in resistance-trained men does not suppress basal testosterone when energy availability is maintained, underscoring energetic sufficiency, not exercise modality, as the principal determinant of androgen tone. Acute competitive stress produces rapid, appraisal-dependent modulation of testosterone independent of SHBG, further demonstrating central regulation.

Across contexts, androgen suppression tracks energetic and psychological constraint and is reversible with restoration of energy balance and recovery. Recognition of this adaptive endocrine phenotype is essential to distinguish functional central suppression from pathological hypogonadism and to guide appropriate clinical evaluation.

Mechanistic Research SummaryCurated from PubMed

This data is for laboratory research purposes only. Not for human or animal consumption.

What is Human Chorionic Gonadotropin (HCG)?

Human chorionic gonadotropin (HCG) is a glycoprotein hormone that stimulates Leydig cell testosterone production and serves as a diagnostic tool to differentiate central (hypothalamic-pituitary) androgen suppression from intrinsic testicular dysfunction. HCG stimulation testing reveals whether suppressed circulating testosterone reflects reversible neuroendocrine adaptation versus primary gonadal failure.

Mechanism of Action

HCG directly binds luteinizing hormone receptors on Leydig cells of the testes, stimulating androgen biosynthesis and testosterone secretion. Under conditions of stress-induced central hypogonadism—characterized by suppressed gonadotropin-releasing hormone (GnRH) pulsatility and reduced luteinizing hormone (LH) signaling—HCG bypasses the compromised hypothalamic-pituitary axis and provides exogenous gonadotropic stimulus. Preserved Leydig cell responsiveness to HCG despite low baseline testosterone confirms intact testicular steroidogenic capacity and implicates hypothalamic-pituitary inhibition as the dominant suppressive mechanism rather than intrinsic testicular pathology.

Observed Laboratory Results

  • Preserved Leydig cell responsiveness: Military field studies and endurance athlete cohorts demonstrate robust testosterone elevation following HCG stimulation despite baseline suppression, confirming functional testicular capacity.
  • Central inhibition dominance: GnRH and LH pulsatility suppression under energetic deficit and psychological stress precedes and predicts testosterone decline independent of intrinsic gonadal dysfunction.
  • Reversibility with recovery: Restoration of energy balance, sleep consolidation, and stress reduction restores hypothalamic-pituitary-gonadal (HPG) axis function and baseline testosterone without pharmacologic intervention, distinguishing functional adaptation from pathological hypogonadism.
Clinical Research Parameters
10 trials

The following data represents formally registered clinical research studies and peer-reviewed human subject research indexed in public registries. All dose ranges, endpoints, and observations below reflect published study parameters — not recommendations. For research reference only.

ClinicalTrials.gov ↗
NCT06026553
UNKNOWNPhase In=400

Assessing Ketorolac (Toradol) at Oocyte Retrieval

To determine if a nonsteroidal anti-inflammatory drug (NSAID), Ketorolac (Toradol), can improve pain control and decrease narcotic use after undergoing egg retrieval.

Study Interventions
Ketorolac (Toradol), Placebo (saline)
Primary Endpoints
Administration of IV narcotic for rescue analgesia during recovery in the post anesthesia care unit (PACU)
Study Period
2022-08-10 → 2025-01
NCT01297465
COMPLETEDPhase IIIn=202

PERgoveriS In Stratified Treatment for Assisted Reproductive Technique

This is a multicenter, multi-national, randomized, open-label comparative trial. After screening, the subjects will start down-regulation treatment on Day 21-22 of the cycle. Down-regulation treatment will start within 2 months following the screening visit. The routine long luteal phase protocol for gonadotropin-releasing hormone (GnRH) agonist treatment will be followed. Once down-regulation has

Study Interventions
Gonal-f®, Pergoveris®, Pergoveris®
Primary Endpoints
Total Number of Oocytes Retrieved
Study Period
2011-05-31 → 2012-10-31
NCT00697255
TERMINATEDPhase IIn=8

A Phase 2 Trial to Evaluate if Corifollitropin Alfa (Org 36286), Followed by a Low Daily Dose of hCG or Recombinant FSH Can Induce Monofollicular Growth in Women With WHO Group II Anovulatory Infertility (P05693)

The primary objective of this trial is to evaluate whether a corifollitropin alfa (Org 36286) regimen applying a single or repeated dose of corifollitropin alfa followed by a low daily dose of Human Chorion Gonadotropin (hCG) or recombinant Follicular Stimulating Hormone (recFSH) can induce monofollicular growth (one follicle ≥18 mm and no other follicle ≥15 mm at day of bolus injection of hCG) in

Study Interventions
corifollitropin alfa, recombinant Follicle Stimulating Hormone (recFSH), human Chorion Gonadotropin (hCG)
Primary Endpoints
Percentage of Participants With Monofollicular Response (Monofollicular Rate)
Study Period
2007-05-15 → 2008-05-15
NCT07394426
NOT YET RECRUITINGEarly Phase In=40

A Phase I Study of PepGNP-ChikV in Healthy Volunteers

This is a Phase I, randomized, single-blind, placebo-controlled, study of four separate dose cohorts, with a 42-day interval between each vaccine dose, of a novel Chikungunya Peptide Immunotherapy Vaccine in Healthy Adults (18-60 years of age). All participants will undergo a screening visit scheduled for a maximum of 28 days before the enrolment in the clinical study and will provide a blood sam

Study Interventions
PepGNP-ChikV, Placebo
Primary Endpoints
To assess the safety of PepGNP-ChikV candidate vaccine; To assess the reactogenicity of PepGNP-ChikV candidate vaccine
Study Period
2026-08-03 → 2028-05-01
NCT05803655
UNKNOWNN/An=850

Outcomes of 36 vs 38 Hour Intervals From Ovulation Trigger To Oocyte Pick-Up:A Multi-Center Randomized Controlled Trial

Women who undergo assisted reproduction technology (ART) treatment will be eligible for this study. The goal of this randomized clinical trial is to compare the outcomes of ART treatment between women who have 36 and 38 hours interval between the administration of ovulation trigger (ovulation trigger medication initiates oocyte maturation and makes it possible for the egg to be collected by aspira

Study Interventions
36-hour duration between ovulation triggering and oocyte pick-up procedure, 38-hour duration between ovulation triggering and oocyte pick-up procedure
Primary Endpoints
Ratio of metaphase-2 oocytes to total number of follicles
Study Period
2023-04-27 → 2025-12
NCT06790706
RECRUITINGPhase IIn=154

IMMUNORARE5: A National Platform of 5 Academic Phase II Trials Coordinated by Lyon University Hospital to Assess the Safety and the Efficacy of the IMMUNOtherapy With Domvanalimab + Zimberelimab Combination in Patients With Advanced RARE Cancers

Immune checkpoint inhibitors (ICI) have revolutionized the management of advanced cancers. However, most rare cancers have been excluded from this progress due to the lack of clinical trials involving these diseases. After the standard first-line treatment, there are no other validated treatments for most of them. The management of these patients in ≥ 2nd line treatment relies on historic poorly e

Study Interventions
DOMVANALIMAB + ZIMBERELIMAB, DOMVANALIMAB + ZIMBERELIMAB + FOLFOX-4
Primary Endpoints
Progression-free survival rate (cohort 1, 3 and 5); Successful hCG normalization rate (cohort 2)
Study Period
2025-10-01 → 2031-06
NCT02940535
UNKNOWNN/An=200

Low Dose GnRHa Early Luteal Phase Down Regulation Versus GnRHa Ultra-short Protocol for Poor Ovarian Response

The management of the poor responder patients is very difficult. Currently, there is no any standard treatment for poor responder patients. The study is designed to test a modified GnRHa protocol for poor ovarian response, low dose GnRHa early luteal phase down regulation, compare with GnRHa ultra-short protocol. This is a randomized controlled trial.

Study Interventions
Diphereline (Triptorelin embonate), Decapeptyl (Triptorelin), human menopausal gonadotropin
Primary Endpoints
live birth
Study Period
2016-12 → 2020-12
NCT02990403
UNKNOWNPhase IVn=500

The Novel Immunomodulatory and Anticoagulant Therapies for Recurrent Pregnancy Loss

In this clinical cohort study, the investigators are going to observe the efficacy of anti-coagulation and immune therapy in the treatment of recurrent pregnancy loss with a prospective randomized controlled trial.

Study Interventions
Aspirin, Heparin, Prednisone
Primary Endpoints
live birth
Study Period
2014-10 → 2018-12-22
NCT02402192
TERMINATEDPhase IVn=201

Type of Gonadotropin and Embryo Kinetics of Development

The study is proposed to determine the effect of three types of gonadotropins that are currently used in protocols of controlled ovarian stimulation in women undergoing in vitro fertilization techniques on the kinetics of embryonic development.

Study Interventions
Corifollitropin alfa
Primary Endpoints
T5 defined as the time that embryo needs to reach a 5-cell stage.
Study Period
2015-04 → 2016-12
NCT04797338
UNKNOWNPhase IVn=100

Gonadotropin Releasing Hormone Agonist (GnRHa) Versus Estrogen and Progesterone for Luteal Support in High Responders

Gonadotropin Releasing Hormone agonist (GnRHa) triggering is used as an alternative to human chorionic gonadotropin (hCG) in GnRH antagonist protocol to eliminate the risk of ovarian hyperstimulation syndrome (OHSS). However, its main disadvantage is a significantly lower pregnancy rate, hypothesized to result from a process called "luteolysis" (demise of the corpora lutea). In order to preserve a

Study Interventions
Synarel, 0.2 Mg/Inh Nasal Spray, Estrofem, Utrogestan
Primary Endpoints
clinical pregnancy rate; Clinical pregnancy rate with fetal heart beat
Study Period
2017-12-29 → 2021-09-30

All data presented on this page is for laboratory research purposes only. HCG (Human Chorionic Gonadotropin) is referenced here as a research reagent. This page does not constitute medical advice, clinical guidance, or endorsement of any compound for human or animal use. All referenced studies are available via PubMed (PMID: 42044038) and the DOI-linked journal publication. Researchers must consult applicable institutional and regulatory frameworks before conducting any protocols.