How many IU are in a milligram of hCG?

It depends on the preparation. For recombinant choriogonadotropin alfa, EU product information states 250 micrograms is equivalent to about 6,500 IU, which works out to roughly 26 IU per microgram or 26,000 IU per mg. Urinary hCG is labeled in USP units by bioassay and has no stated mass equivalent.

What is the difference between recombinant and urinary hCG?

Urinary hCG is purified from human pregnancy urine and labeled in USP units. Recombinant hCG (choriogonadotropin alfa) is expressed in Chinese hamster ovary cells, labeled by mass, and its activity is calibrated against an international reference preparation.

What is the half-life of hCG?

The Ovidrel label reports a mean terminal half-life of 29 ± 6 hours after a single 250 microgram subcutaneous dose of recombinant hCG in healthy female volunteers, and 26.5 ± 2.5 hours after intravenous administration.

HCG / Human Chorionic Gonadotropin

aka Human Chorionic Gonadotropin · Novarel · Pregnyl · Ovidrel

CAS 9002-61-3

strong evidenceInvestigational

HCG / Human Chorionic Gonadotropin in brief

Human chorionic gonadotropin (hCG) is a placental glycoprotein hormone built from an alpha and a beta subunit that acts on the LH/choriogonadotropin receptor. Urinary-derived hCG is labeled in USP units; recombinant choriogonadotropin alfa is labeled by mass, with 250 micrograms stated as about 6,500 IU. Its reported terminal half-life is about 29 hours.

hCG structure: alpha and beta subunits explained

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Long-form breakdowns

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Short-form clips

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Recombinant vs urinary hCG

Two kinds of hCG appear in the research literature and in FDA labeling, and they are measured differently.

	Urinary-derived hCG	Recombinant hCG (choriogonadotropin alfa)
Source	Purified from human pregnancy urine	Expressed in Chinese hamster ovary (CHO) cells
Labeled strength	USP units (Novarel: 5,000 or 10,000 USP units per vial)	Mass (Ovidrel: 250 micrograms)
Potency basis	Bioassay against a reference standard	Rat seminal vesicle weight bioassay, calibrated against the third international reference preparation (IS 75/587)
FDA label example	Novarel, initial US approval 1974	Ovidrel

The Ovidrel label describes the recombinant beta chain's structure and glycosylation pattern as very similar to urinary hCG, and reports a registration study in which 250 micrograms of Ovidrel was compared with 10,000 USP units of an approved urinary hCG product.

Sources

Half-life and identifiers

Per the Ovidrel label, after a single 250 microgram subcutaneous dose in healthy female volunteers, peak serum concentration was reached at 12 to 24 hours and the mean terminal half-life was 29 ± 6 hours, with bioavailability of about 0.4. After intravenous administration, the label reports an initial half-life of 4.5 ± 0.5 hours and a terminal half-life of 26.5 ± 2.5 hours.

Identifier	Chorionic gonadotropin	Choriogonadotropin alfa
FDA UNII	20ED16GHEB	6413W06WR3
CAS numbers listed in FDA GSRS	9002-61-3, 177073-44-8	9002-61-3, 177073-44-8
DrugBank	DB09126	DB00097

Sources

Converting IU to mg: a worked example

There is no universal IU-to-mg factor for hCG, because IU measure biological activity and activity per milligram varies by preparation. One stated basis exists for recombinant hCG: the EU product information for Ovitrelle (choriogonadotropin alfa) states that 250 micrograms is equivalent to approximately 6,500 IU.

Conversion basis: 6,500 IU ÷ 250 micrograms = 26 IU per microgram, or about 26,000 IU per mg
Worked example: 5,000 IU ÷ 26 IU per microgram ≈ 192 micrograms (0.19 mg)
Second example: 10,000 IU ÷ 26 IU per microgram ≈ 385 micrograms (0.38 mg)

This ratio applies only to recombinant choriogonadotropin alfa calibrated the way that label describes. Urinary hCG is labeled in USP units assigned by bioassay, its label states no mass equivalent, and the ratio should not be applied to urinary or research-market material. The unit converter treats IU as preparation-specific for the same reason.

Sources

Ovitrelle EU product information (EMA), section 2: 250 micrograms equivalent to approximately 6,500 IU

Common questions

How many IU are in a milligram of hCG?: It depends on the preparation. For recombinant choriogonadotropin alfa, EU product information states 250 micrograms is equivalent to about 6,500 IU, which works out to roughly 26 IU per microgram or 26,000 IU per mg. Urinary hCG is labeled in USP units by bioassay and has no stated mass equivalent.
What is the difference between recombinant and urinary hCG?: Urinary hCG is purified from human pregnancy urine and labeled in USP units. Recombinant hCG (choriogonadotropin alfa) is expressed in Chinese hamster ovary cells, labeled by mass, and its activity is calibrated against an international reference preparation.
What is the half-life of hCG?: The Ovidrel label reports a mean terminal half-life of 29 ± 6 hours after a single 250 microgram subcutaneous dose of recombinant hCG in healthy female volunteers, and 26.5 ± 2.5 hours after intravenous administration.

Full Research Data

Overview

Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone produced by the placenta during pregnancy. Structurally similar to LH, it stimulates testosterone production in males and supports corpus luteum function in females. FDA-approved for fertility treatment and male hypogonadism.

PubMed results: 153 · Human studies: 99 · Animal studies: 111

Dosing Ranges

Ranges reflect protocols studied in published research and animal-model extrapolation. Presented for research purposes only, not a recommendation or instruction for human use.

FDA-approved dosing varies by indication

Intramuscular/Subcutaneous Injection — standard range 1000-2500 IU, 2-3 times weekly (hypogonadism)

Half-Life

24-36 hours (high confidence)

Observed Benefits

Fertility and ovulation-trigger research (Strong clinical): Human chorionic gonadotropin has been extensively studied and is clinically established in fertility research and assisted-reproduction protocols for supporting corpus luteum function and triggering final oocyte maturation in IVF settings
LH-mimetic testicular steroidogenesis research (Strong clinical): Structurally similar to luteinizing hormone, HCG has been researched for stimulating Leydig-cell testosterone production and is used clinically in male hypogonadism and related reproductive-endocrine research
Female infertility and pregnancy-loss research contexts (Moderate clinical): Investigational and clinical programs have examined HCG across infertility, PCOS-related subfertility, adenomyosis research, and pregnancy-loss contexts, with outcome data varying by indication and protocol design

Side Effects

Ovarian hyperstimulation syndrome (OHSS) risk in fertility research — Serious, Uncommon. In controlled ovarian-stimulation research settings, HCG used as a trigger has been associated with OHSS risk, particularly in high-responder populations, and is a well-documented class concern in assisted-reproduction literature
Injection site reactions and local discomfort — Mild, Common. Subcutaneous or intramuscular administration in clinical use commonly produces mild local injection-site reactions
Gynecomastia or fluid retention (androgen-aromatization contexts) — Mild, Uncommon. Because HCG elevates testicular testosterone, research and clinical observations note estrogen-related effects such as gynecomastia or edema in some male hypogonadism contexts

Contraindications

Hormone-dependent neoplasms (Established): HCG-driven increases in sex steroids raise clinical concern in androgen- or estrogen-sensitive malignancies, and product labeling frameworks restrict use in certain hormone-dependent tumor settings
Primary ovarian failure or uncontrolled thyroid disease research exclusions (Clinical): Fertility research protocols typically exclude primary gonadal failure where HCG cannot restore ovulatory competence, and uncontrolled endocrine comorbidities such as thyroid dysfunction may confound reproductive endpoints

Storage

Lyophilized (powder): Refrigerated (2-8°C), Up to 24 months. Light sensitive: yes, store dark

Reconstituted (solution): Refrigerated (2-8°C), 4-6 weeks. Solvent: Bacteriostatic water

Clinical Trials

NCT03682614 — Effect of Intrauterine Injection of HCG on Clinical Pregnancy Outcome in Repeated Implantation Failure Patients (NA), status: COMPLETED. Indications: Infertility
NCT02420704 — Effect of Endometrial Thickness on IVF Outcome, status: UNKNOWN. Indications: Infertility
NCT04407871 — Acupuncture and Chinese Herbal Medicine to Improve Live Birth Rate of in Vitro Fertilization (IVFAct) (NA), status: UNKNOWN. Indications: In Vitro Fertilization
NCT00696800 — A Study to Investigate the Efficacy and Safety of a Single Injection of Corifollitropin Alfa (Organon 36286) for Ovarian Stimulation Using Daily Recombinant Follicle Stimulating Hormone (FSH) as Reference (P05787) (PHASE3), status: COMPLETED. Indications: In Vitro Fertilization
NCT03712683 — Thyroxin in Subclinical Hypothyroidism (NA), status: COMPLETED. Indications: Sub Clinical Hypothyroidism, Pregnancy Loss
NCT01882166 — Time-lapse Monitoring of Early Embryo Development After Ovarian Stimulation During Infertility Treatment (NA), status: TERMINATED. Indications: Infertility, Female
NCT06913075 — FET in Adenomyosis (NA), status: NOT_YET_RECRUITING. Indications: Adenomyosis
NCT01714882 — Stress Management for Couples Undergoing In Vitro Fertilization (IVF) (PHASE2), status: COMPLETED. Indications: Infertility
NCT03115320 — Frozen-thawed Embryo Transfer in a Natural Cycle: hCG Triggering Versus LH Home Test (PHASE4), status: TERMINATED. Indications: Infertility
NCT04297553 — Fresh Versus Freeze-only After CAPA IVM on PCOS Patients (NA), status: COMPLETED. Indications: PCOS, IVM, Embryo Transfer
NCT05586802 — Sex Steroids Balance for Metabolic and Reproductive Health in Klinefelter Syndrome (PHASE3), status: RECRUITING. Indications: Klinefelter Syndrome
NCT06026553 — Assessing Ketorolac (Toradol) at Oocyte Retrieval (PHASE1), status: UNKNOWN. Indications: Infertility, Infertility, Female, Oocyte Retrieval, Postoperative Pain, Embryo Transfer
NCT01856062 — Ovulation Induction With Clomiphene Citrate and Dexamethasone (PHASE4), status: UNKNOWN. Indications: Infertility
NCT01094496 — A Study of the CDX-1307 Vaccine Regimen in Patients With Newly Diagnosed Muscle-Invasive Bladder Cancer (The "N-ABLE" Study) (PHASE2), status: TERMINATED. Indications: Bladder Cancer
NCT01468441 — Ovarian Stimulation Using Recombinant Follicle-stimulating Hormone (FSH) and Gonadotrophin Releasing Hormone (GnRH) Agonist in Alternate Days (NA), status: COMPLETED. Indications: Infertility
NCT02357095 — UACE Followed by Uterine Suction Curettage for the Treatment of Caesarean Scar Pregnancy (NA), status: COMPLETED. Indications: Caesarean Scar Pregnancy
NCT06228131 — Detection of hCG in Early Pregnancy Clinical Samples, status: COMPLETED. Indications: Early Pregnancy
NCT01910766 — Coenzyme Q10 and Clomiphene Citrate (CC) for Ovulation Induction in Polycystic Ovary Syndrome (NA), status: COMPLETED. Indications: Polycystic Ovary Syndrome
NCT04855383 — Intramuscular Injection of Human Chorionic Gonadotropin in Frozen Embryo Transfer Cycles (NA), status: COMPLETED. Indications: Embryo Implantation
NCT00920361 — Designated Drug Use Investigation 1 of Follistim Injection (Study P06130)(COMPLETED), status: COMPLETED. Indications: Fertilization in Vitro