How effective is hCG at raising testosterone?

Almost every confusion about testosterone therapy and fertility dissolves once you see one measurement. In healthy young men studied by Coviello and colleagues, baseline intratesticular testosterone was about 1,174 nmol/L, while serum testosterone was about 14 nmol/L.^[1] Serum testosterone is roughly 1.2% of the intratesticular concentration — the blood level is a faint echo of what the testis holds inside itself.

Sperm production depends on that intratesticular pool, not on the blood level. This is why exogenous testosterone can normalise a lab report and simultaneously shut down fertility: it fills the serum compartment while the pituitary stops sending LH, and the intratesticular pool collapses. Whether testosterone reaches the blood by gel or injection makes no difference to this mechanism.

The Coviello study is the cleanest demonstration in the literature. Twenty-nine healthy men, mean age 24, received 200 mg of testosterone enanthate weekly for three weeks — enough to suppress the pituitary — plus either saline placebo or hCG at 125, 250 or 500 IU every other day. Intratesticular testosterone fell 94% on placebo, 25% at 125 IU, 7% at 250 IU, and actually rose 26% at 500 IU. The relationship with dose was linear (P<0.001).^[1]

One detail deserves to be stated plainly rather than glossed over: LH fell to about 5% and FSH to about 3% of baseline in every group, including the hCG groups. hCG does not keep the hypothalamic–pituitary–gonadal axis switched on. It bypasses the axis, substituting for LH at the receptor and driving the Leydig cell directly.

The clinical translation of that physiology came in 2013. Twenty-six hypogonadal men on testosterone replacement also received hCG 500 IU intramuscularly every other day, with a mean follow-up of 6.2 months. Total testosterone rose from 207.2 to 1,055.5 ng/dL (p<0.0001) and free testosterone from 8.1 to 20.4 pg/mL (p=0.02). Estradiol rose from 2.2 to 3.7 pg/mL, which did not reach significance (p=0.11).^[2]

The fertility outcome is the point of the study. No man became azoospermic, semen parameters were unchanged over more than a year of follow-up, and nine of the 26 contributed to a pregnancy while on treatment. That combination — a normalised blood level and preserved sperm production — is not achievable with testosterone alone, whatever the dose or route. It also does not change the separate question of cardiovascular safety on testosterone therapy, which is monitored on its own terms.

A multi-institutional retrospective series followed 20 men taking about 2,000 IU of hCG per week as monotherapy for a median of 8 months. Total testosterone rose from 362 to 519.8 ng/dL — a 49.9% increase (p=0.006). Half of the men reported symptom improvement, and no adverse events were recorded.^[3] A separate series of 31 men on hCG monotherapy whose baseline testosterone was already above 300 ng/dL reported improvement in erectile dysfunction in 86% (19/22) and in libido in 80% (20/25), with no change in haematocrit, HbA1c, PSA or estradiol and no thromboembolic events.^[4]

The one randomised comparison is instructive. Habous and colleagues randomised 282 hypogonadal men to clomiphene citrate 50 mg, hCG 5,000 IU twice weekly, or both, for three months. Mean testosterone rose from 2.31 to 5.17 nmol/L — an increase of roughly 223% — with no significant difference between the three arms. Symptom scores, however, favoured combination therapy (qADAM 15.13) over clomiphene alone (12.73) or hCG alone (11.82), p<0.01.^[5] It is worth being honest that the absolute endpoint testosterone in that trial remained modest.

The largest dataset to date is a 2026 retrospective cohort of 6,999 men, 91% of whom were on hCG combined with testosterone therapy. All fertility-sparing strategies produced substantial rises in both total and free testosterone, reaching physiological levels of roughly 23.6–26.5 nmol/L, with similar quality-of-life gains across strategies. The cohort also confirmed that hCG plus TRT suppresses both LH and FSH.^[6]

This is the most important clinical point in the article. hCG can only push a gland that still works. In secondary (hypogonadotropic) hypogonadism — LH and FSH low or inappropriately normal, testis structurally healthy — the signal is missing and hCG supplies it. That is where hCG shines. In primary (hypergonadotropic) hypogonadism, LH is already elevated because the pituitary is shouting at a failing testis; adding another LH analog has very little left to recruit. Your LH, FSH and testosterone panel is what separates the two, and it should be interpreted before any therapy is chosen.

Stimulation testing puts a number on the ceiling. Belli and colleagues gave 5,000 IU of hCG to 13 men with Klinefelter syndrome and 12 controls, profiling steroids by LC-MS/MS. Leydig cells in the Klinefelter men did respond — progesterone, 17-hydroxyprogesterone, testosterone and estradiol all rose — but testosterone output was impaired relative to controls.^[7] A partial response, set not by the drug but by the tissue.

A 2025 meta-analysis pooled 41 studies and 1,673 men with pathological gonadotropin deficiency, mean age 25. After a median 18 months of gonadotropin treatment, mean sperm concentration was 11.6 M/mL (95% CI 8.4–14.9). The proportion reaching each threshold fell steeply: 78% achieved any sperm at all, 55% exceeded 1 M/mL, 36% exceeded 5 M/mL, 24% exceeded 10 M/mL and 15% exceeded 20 M/mL. Combined hCG plus FSH beat hCG monotherapy for sperm output, although testosterone and testicular-volume gains were similar between the two.^[8]

An earlier meta-analysis found an overall 75% (69–81) success rate for achieving any spermatogenesis on gonadotropins, with a mean sperm concentration of 5.92 M/mL. Results were better in post-pubertal-onset than pre-pubertal-onset disease (84% vs 68%) and better with hCG plus FSH than hCG alone — and, importantly for men coming off testosterone, prior testosterone therapy did not compromise the outcome.^[9][13]

The teaching point behind both papers: hCG replaces LH, not FSH. It restores the androgen signal inside the testis, which is necessary but often not sufficient — sustained sperm production usually also needs FSH.

The ranges below are reported in a 2025 review of fertility-sparing strategies and are given for orientation only. hCG is a prescription injectable, used off-label for this indication in most jurisdictions, and every regimen is individualised and physician-supervised. Nothing here is a protocol to self-administer.^[10]

• Hypogonadotropic hypogonadism monotherapy: around 3,000 IU three times weekly.
• Low-dose fertility preservation alongside testosterone therapy: 500 IU every other day.
• Testicular-volume preservation: 1,500 IU weekly.
• Intermittent stimulation: 3,000 IU every other day for four weeks, repeated every 6 months.
• Monotherapy for symptoms has been used at around 2,000 IU per week.

Sources: Hochu et al., Transl Androl Urol 2025^[10]; Madhusoodanan et al. 2019^[3].

Estradiol. hCG drives testicular aromatase activity. In stimulation testing the estradiol-to-testosterone ratio rose significantly after hCG in Klinefelter men (p=0.009) and in controls (p<0.001).^[7] In the TRT-plus-hCG series the estradiol rise was small and not significant.^[2] Estradiol should be monitored; gynecomastia and fluid retention are the practical concerns.

Evidence quality. Most hCG-monotherapy data are small retrospective series. There is no large randomised trial of hCG versus testosterone therapy with hard clinical outcomes, and the enthusiasm around hCG currently outruns the evidence base behind it.

Practicalities. It is an injection, usually off-label for this indication, and cost and availability vary considerably by country and pharmacy.

Guideline position. The AUA testosterone-deficiency guidance states that clinicians may use hCG in men with testosterone deficiency who wish to maintain fertility, and that exogenous testosterone should not be prescribed to men currently trying to conceive.^[11][12]

Monitoring. As with any androgen-raising therapy, haematocrit, PSA where appropriate, and symptoms should be tracked over time.

hCG raises testosterone, and it does so in a way nothing else does: from inside the testis, preserving the intratesticular pool, testicular volume and fertility that exogenous testosterone sacrifices.^[1][2] Its ceiling is biological. Where Leydig cells are healthy and only the signal is missing, the response is substantial; where the testis itself is failing, an LH analog has little left to recruit.^[7]

The evidence base is real but uneven — one elegant physiology trial, a handful of small clinical series, one short randomised comparison and a large retrospective cohort. That is enough to justify hCG in the right patient, and not enough to make it a default.^[6]

This article is educational and not medical advice. hCG is a prescription medication; whether it is appropriate, at what dose, and alongside what monitoring, is a decision to make with your own physician.