Testosterone Cypionate Fertility Suppression: A Severity Grading Rubric

How sperm suppression is categorized

Semen analysis is the measure the clinical studies use. The categories are a reduced but present count (oligospermia), severe oligospermia defined as under 1 million sperm/mL, cryptozoospermia (sperm seen only after the sample is centrifuged), and azoospermia (no sperm found) [3][1]. The Depo-Testosterone label lists oligospermia at high dosages among its adverse reactions rather than grading it [2]. The recovery studies sort men by these semen analysis categories [3][1].

How testosterone cypionate suppresses sperm production

The Depo-Testosterone label describes the mechanism directly: during exogenous androgen administration, endogenous testosterone release is inhibited through feedback inhibition of pituitary luteinizing hormone (LH), and at large doses of exogenous androgens spermatogenesis may also be suppressed through feedback inhibition of pituitary follicle stimulating hormone (FSH) [2]. Testosterone itself is an absolute requirement for spermatogenesis [6].

The clearest numbers come from a 2005 randomized study of 29 men with normal reproductive physiology who received 200 mg testosterone enanthate weekly plus either saline placebo or 125, 250 or 500 IU hCG every other day for 3 weeks [7]. In the testosterone-plus-placebo group, LH fell to 5% and FSH to 3% of baseline, and intratesticular testosterone fell 94%, from 1234 to 72 nmol/L [7]. At baseline in that study, serum testosterone was about 1.2% of the intratesticular concentration [7].

The four semen analysis categories

Oligospermia: sperm present but reduced

Oligospermia means sperm are present at a reduced count. The Depo-Testosterone label says it may occur at high dosages [2]. The recovery studies enrolled men at the severe end, so this category is covered least directly [3][1].

Severe oligospermia: under 1 million sperm/mL

A 2015 case series of 49 men with azoospermia or severe oligospermia (under 1 million/mL) while taking exogenous testosterone used this cutoff as its entry criterion [3]. In a study of healthy men receiving weekly testosterone enanthate for contraception, four pregnancies occurred during 49.5 person-years when sperm counts were 0.1 to 3 million/mL, and none during 230.4 person-years in azoospermic men [8]. That range is broader than the under-1-million/mL category used in the 49-man case series [3].

Cryptozoospermia

Sperm are present but only in the centrifuged pellet. Among 66 men treated for infertility after testosterone use, 91.7% of cryptozoospermic men reached a total motile count above 5 million within 12 months of stopping testosterone and starting high-dose hCG plus a selective estrogen receptor modulator, against 64.8% of azoospermic men; the authors noted that this difference did not predict a failure of sperm recovery [1].

Azoospermia

No sperm on analysis. In a series of 4,400 men presenting for fertility evaluation, 59 (1.3%) reported taking testosterone, and 88.4% of those men were azoospermic while on it [4]. Of the men without another known cause for azoospermia, 65% recovered spermatogenesis within 6 months of stopping [4]. These were men who came to a fertility clinic, so the figures do not describe all men on testosterone.

The same dose produces different categories

The WHO contraceptive study enrolled 399 healthy, fertile men and gave every one of them 200 mg testosterone enanthate weekly by intramuscular injection [8]. The target was suppression to azoospermia or 3 million/mL or less, and it was not universal: with that same weekly dose, eight men had inadequate suppression of spermatogenesis and four had escape from suppression [8]. A man's category cannot be read off his dose.

What predicts recovery

The largest dataset comes from an integrated analysis of 30 studies and 1549 healthy eugonadal men on androgen or androgen-progestin contraception, not from men with hypogonadism [9]. In that analysis, the median time for sperm concentration to recover to 20 million/mL was 3.4 months [9]. Recovery to that threshold occurred in 67% by 6 months, 90% by 12 months, 96% by 16 months and 100% by 24 months, and was faster with shorter-acting testosterone preparations, shorter treatment, older age and a higher baseline sperm count [9].

In the treatment series of 66 men, 70% overall reached a total motile count above 5 million within 12 months, and both older age and longer duration of testosterone use predicted slower recovery [1]. The 59-man clinic series found 65% recovery by 6 months in men without other identified causes of azoospermia [4]. The age direction differs by population: in the contraception analysis of healthy men, older age predicted faster recovery [9].

Strategies that have been studied

hCG while testosterone continues. In the 29-man dose-response study, intratesticular testosterone after 3 weeks was 25% below baseline with 125 IU hCG every other day, 7% below baseline with 250 IU, and 26% above baseline with 500 IU [7]. The endpoint was intratesticular testosterone, not sperm count or pregnancy.

hCG plus a second agent. Forty-nine men with azoospermia or severe oligospermia on testosterone received 3,000 units hCG subcutaneously every other day plus clomiphene, tamoxifen, anastrozole or recombinant FSH; spermatogenesis returned or improved in 47 (95.9%), with an average time of 4.6 months and a mean first density of 22.6 million/mL, and no significant difference by type of testosterone used [3]. The 66-man series stopped testosterone and used high-dose hCG plus a selective estrogen receptor modulator, reaching the 70% figure above [1].

Clomiphene instead of testosterone. A 2019 review says clomiphene acts centrally to raise LH and FSH and does not suppress the hypothalamic-pituitary-gonadal axis, preserving intratesticular testosterone production and spermatogenesis, which it describes as especially useful in hypogonadal men interested in fertility [10].

What the guideline says

The Endocrine Society's 2018 guideline recommends against starting testosterone therapy in men who are planning fertility in the near term [5].

Bottom line

Sperm suppression is described by semen analysis rather than by a numbered grade. A 49-man series reported return or improvement of spermatogenesis for men with severe oligospermia or azoospermia combined [3]. A separate series reported recovery outcomes for cryptozoospermia and azoospermia, with cryptozoospermic men reaching the study threshold more often [1]. Recovery is common but takes months, and its predictors differ between the populations studied [9][1].