HCG

HCG (human chorionic gonadotropin) is a hormone that plays a central role in human reproduction. In women, it triggers the final maturation and release of eggs (ovulation) and supports the early stages of pregnancy Role of gonadotropin-releasing hormone agonists, human chorionic gonadotropin (hCG), progesterone, and estrogen in luteal phase support after hCG triggering, and when in pregnancy hormonal support can be stopped. In men, it stimulates the testes to produce testosterone and sperm, making it a key therapy for certain types of male infertility caused by hormonal deficiency (hypogonadotropic hypogonadism) Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. HCG is a glycoprotein made up of two subunits, and it is available as both a urinary-derived and a recombinant prescription medication Recombinant human chorionic gonadotropin (rhCG) in assisted reproductive technology: results of a clinical trial comparing two doses of rhCG (OvidrelR) to urinary hCG (ProfasiR) for induction of final follicular maturation in in vitro fertilization–embryo transfer+1. Its effects are mediated by activating the same receptor as luteinizing hormone (LH) Human Chorionic Gonadotropin (hCG)—An Endocrine, Regulator of Gestation and Cancer.

HCG mimics the action of luteinizing hormone (LH) by binding to and activating the LH/choriogonadotropin receptor (LHCGR) on target cells Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. This receptor is present on ovarian cells in women and on Leydig cells in the testes Human chorionic gonadotropin (hCG) in the male reproductive tract. Upon binding, HCG triggers a cascade that increases cyclic AMP (cAMP) inside the cell, which turns on the enzyme pathways needed to produce sex steroids—primarily progesterone in the ovary and testosterone in the testes N- and O-glycosylation patterns and functional testing of CGB7 versus CGB3/5/8 variants of the human chorionic gonadotropin (hCG) beta subunit+1. In the ovary, this leads to the final steps of egg maturation and the formation of the corpus luteum, which sustains early pregnancy. In the testes, HCG drives Leydig cells to synthesize testosterone, which is essential for sperm production Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1.

HCG’s effects are well documented in several contexts.

• Ovulation trigger: A single injection of HCG reliably induces the final maturation of eggs in assisted reproductive technology (ART), with both recombinant and urinary forms showing comparable effectiveness Recombinant human chorionic gonadotropin (rhCG) in assisted reproductive technology: results of a clinical trial comparing two doses of rhCG (OvidrelR) to urinary hCG (ProfasiR) for induction of final follicular maturation in in vitro fertilization–embryo transfer+1.
• Male hypogonadism: In men with low gonadotropin levels, HCG monotherapy can restore normal testosterone production, and when combined with FSH or hMG, it can induce spermatogenesis, often after months of treatment Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+2.
• Biomarker: HCG is a sensitive marker for pregnancy and certain tumors, including gestational trophoblastic disease and germ cell tumors Diagnosis of hydatidiform mole and persistent trophoblastic disease: diagnostic accuracy of total human chorionic gonadotropin (hCG), free hCG α- and β-subunits, and their ratios+1. In low-risk trophoblastic tumors, normalization of serum HCG served as a treatment endpoint in recent trials Avelumab Plus Methotrexate for Gestational Trophoblastic Tumors.
• Luteal support: Low-dose HCG can support the corpus luteum in ART cycles, although protocols vary Role of gonadotropin-releasing hormone agonists, human chorionic gonadotropin (hCG), progesterone, and estrogen in luteal phase support after hCG triggering, and when in pregnancy hormonal support can be stopped.

HCG protocols vary significantly depending on the goal. For male fertility induction in hypogonadotropic hypogonadism, research has used intramuscular doses of 5,000 IU twice weekly for a mean of 19 months, with the addition of human menopausal gonadotropin (hMG) if sperm count remained low Combined Human Chorionic Gonadotropin (HCG) and Human Menopausal Gonadotropin (hMG) Treatment in Gonadotropin‐Deficient Males with Pituitary Dwarfism. More recent practitioner consensus favors lower starting doses of 1,500–3,000 IU subcutaneously 2–3 times per week, with the understanding that spermatogenesis often requires 6–12 months or more Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. In contrast, a single high dose (typically 5,000–10,000 IU urinary or 250 μg recombinant) is given to trigger ovulation in IVF and timed intercourse, timed precisely to follicle maturation Recombinant human chorionic gonadotropin (rhCG) in assisted reproductive technology: results of a clinical trial comparing two doses of rhCG (OvidrelR) to urinary hCG (ProfasiR) for induction of final follicular maturation in in vitro fertilization–embryo transfer+1. Additional low-dose regimens are used for luteal support or to maintain testicular function during testosterone therapy Role of gonadotropin-releasing hormone agonists, human chorionic gonadotropin (hCG), progesterone, and estrogen in luteal phase support after hCG triggering, and when in pregnancy hormonal support can be stopped.

Injectable HCG typically comes as a dry (lyophilized) powder that must be mixed with a diluent before use. Bacteriostatic water is the preferred diluent for multiple-dose vials, as it helps prevent bacterial growth (practitioner consensus). Sterile water can be used if the entire mixture will be used within 24 hours. To reconstitute, let the vial reach room temperature, inject the diluent slowly down the wall, and gently swirl—do not shake, as HCG is a delicate glycoprotein Avelumab Plus Methotrexate for Gestational Trophoblastic Tumors+1. After mixing, store the solution in the refrigerator at 2–8°C. With bacteriostatic water, the solution may be used for up to 30–60 days; with sterile water, discard after 24 hours. Freeze single-use aliquots at -20°C for longer storage, but avoid repeated thawing (practitioner consensus). All reconstitution math—volumes, concentrations, and syringe units—is handled by the interactive calculator on this page.

HCG has important practical interactions, particularly with other fertility medications. When used with FSH or hMG (menotropins), the combined effect more robustly stimulates spermatogenesis than HCG alone Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. This is because HCG provides LH-like activity to Leydig cells, while FSH directly supports the Sertoli cells where sperm mature. Conversely, using HCG while monitoring hCG levels for tumors (e.g., gestational trophoblastic disease) can interfere with disease tracking, so exogenous HCG should be avoided in such patients Avelumab Plus Methotrexate for Gestational Trophoblastic Tumors. HCG can also cross-react with the thyroid receptor at very high levels, potentially worsening hyperthyroid states Longitudinal evaluation of recurrent thyrotoxicosis in a single patient across four pregnancies: a case report and literature review.

In medical practice, HCG is often used for extended periods when the goal is fertility. Cycles of less than 3 months are unlikely to yield sperm in previously azoospermic men, and protocols may continue for a year or more Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. The idea of short 'on/off' cycles comes from athletic communities and is not supported by clinical trial data. Evidence suggests that HCG does not cause rapid desensitization at testicular LH receptors, but prolonged use without monitoring can lead to excessive estradiol, water retention, and other estrogenic effects Recombinant human chorionic gonadotropin (rhCG) in assisted reproductive technology: results of a clinical trial comparing two doses of rhCG (OvidrelR) to urinary hCG (ProfasiR) for induction of final follicular maturation in in vitro fertilization–embryo transfer+1. Therefore, reassessment every 4–8 weeks with blood work is recommended.

HCG is frequently part of multi-compound stacks in both clinical and community protocols. The best-studied combination is HCG with FSH or hMG for male infertility Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. Community practices also pair HCG with selective estrogen receptor modulators (SERMs) like clomiphene during post-cycle therapy to restart natural testosterone production while preserving testicular size (practitioner consensus). Less evidence exists for stacking HCG with growth hormone secretagogues or other peptides; such combinations increase monitoring complexity without clear additive fertility benefit.

HCG is FDA-approved as a prescription drug for several indications, including ovulation induction and treatment of prepubertal cryptorchidism. It is widely available from licensed pharmacies Therapeutic benefits of gonadotropins in male hypogonadotropic hypogonadism: a focus on spermatogenesis and fertility+1. Because it can stimulate testosterone production in males, HCG is on the World Anti-Doping Agency (WADA) Prohibited List, and athletes are tested for it via urine Urine reference intervals for human chorionic gonadotropin (hCG) isoforms by immunoextraction-tandem mass spectrometry to detect hCG use. In diagnostic oncology, HCG levels are used to guide treatment, making possession and monitoring in that context strictly medical Avelumab Plus Methotrexate for Gestational Trophoblastic Tumors.

Most common side effects of HCG stem from its hormone-stimulating properties. In men, increased estradiol can cause breast tenderness, swelling (gynecomastia), water retention, and mood changes Recombinant human chorionic gonadotropin (rhCG) in assisted reproductive technology: results of a clinical trial comparing two doses of rhCG (OvidrelR) to urinary hCG (ProfasiR) for induction of final follicular maturation in in vitro fertilization–embryo transfer+1. In women undergoing fertility treatment, a rare but serious risk is ovarian hyperstimulation syndrome (OHSS), marked by abdominal bloating, rapid weight gain, and, in severe cases, fluid in the chest or abdomen Atypical presentation of severe ovarian hyperstimulation syndrome complicated by isolated pleural effusions: a case series and literature review+1. HCG should not be used in patients with hormone-sensitive cancers or those being monitored for hCG-secreting tumors, as it can confound test results Avelumab Plus Methotrexate for Gestational Trophoblastic Tumors+1. A case of acute intermittent porphyria flare after HCG has been reported Human Chorionic Gonadotropin (hCG) Injections Exacerbating Acute Intermittent Porphyria in a 34-Year-Old Woman. Monitoring includes regular measurements of testosterone, estradiol, and, when relevant, semen analysis and ovarian ultrasound.