What FSH, LH, And Testosterone Reveal About Male Fertility

A normal testosterone result can sit right next to a fertility problem, and it surprises a lot of men. For sperm production, one number matters less than the pattern across three hormones: FSH, LH, and testosterone. FSH signals the testes to make sperm, LH signals them to make testosterone, and testosterone supports sperm development inside the testicle. Read together, they show whether a fertility issue starts in the brain, the testes, or the signal between them. Marek Health builds its men's hormone testing around that full picture, and its testosterone health resources show why a single value rarely tells the whole story.

FSH, LH, and testosterone are the three hormones that run male fertility. The pituitary gland in the brain releases FSH and LH. FSH drives sperm production, LH drives testosterone production, and testosterone sustains both. Tested together, their pattern points to whether reduced fertility traces to the testes or the brain (Bhasin et al., 2018).

One point is worth flagging early. Adding testosterone from outside the body can lower fertility rather than help it.

How FSH, LH, and testosterone control male fertility

Male fertility runs on a feedback loop between the brain and the testes, the hypothalamic-pituitary-gonadal axis. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which tells the pituitary to send out LH and FSH. Both act on the testes, which produce testosterone that feeds back to keep the loop balanced. When one part falters, fertility can fall even when a man feels fine.

FSH and sperm production

FSH (follicle-stimulating hormone) acts on Sertoli cells, the cells that carry developing sperm to maturity. Low FSH points to a weak signal from the pituitary or hypothalamus. High FSH usually means the testes aren't responding, so the brain keeps raising the volume. That pattern often signals primary testicular trouble.

LH and testosterone production

LH (luteinizing hormone) acts on Leydig cells, which make most of a man's testosterone. Low LH suggests the brain's signal is weak. High LH with low testosterone suggests the testes can't keep up. Because LH and testosterone move together, reading them side by side tells a clinician more than either alone.

Testosterone's role in fertility

Testosterone does two jobs. It supports libido and muscle mass and drives sperm production inside the testicle, where levels run far higher than in the blood. Low testosterone can track with low sperm counts, reduced sex drive, and fatigue, though these symptoms are nonspecific. High testosterone from an outside source is a different matter, and a recognized, often-missed contributor to male infertility, covered below.

Who should get a male hormone test?

Testing FSH, LH, and testosterone is worth discussing with a provider when there's a real reason to question fertility, not a routine screen for every man. Low testosterone is common. The Endocrine Society estimates about 35% of men older than 45, and 30 to 50 percent of men with obesity or type 2 diabetes, have hypogonadism (Endocrine Society). A few situations make testing worthwhile.

• You have tried to conceive for 12 months, or 6 months if your partner is over 35.

• A semen analysis came back with low count or poor motility and no clear cause.

• You have signs of low testosterone, such as low libido, fatigue, or erectile changes.

• You have a history of undescended testicles, testicular injury, or steroid use.

• You are considering testosterone therapy and want to know its effect on fertility first.

The Endocrine Society advises against blanket testosterone screening in men without symptoms (Bhasin et al., 2018).

What does hormone testing involve?

A male fertility hormone test is a simple blood draw measuring FSH, LH, and testosterone, sometimes with prolactin or estradiol. A clinician reads them with your history and, when relevant, a semen analysis. The basic panel needs no imaging, though results may prompt further testing.

When should you test?

Testosterone follows a daily rhythm and peaks in the morning, so timing matters. The AUA recommends early-morning samples and two separate measurements before calling testosterone low (Mulhall et al., 2018). One low afternoon reading isn't enough to act on.

What the blood draw is like

The draw takes a few minutes from a vein in your arm. If fertility is the question, a clinician may add a semen analysis to check sperm count, movement, and shape (morphology).

How to prepare for accurate results

Good prep keeps the numbers honest. A few steps before your draw help.

• Tell your clinician about every medication and supplement, including hormone products, since several change these levels.

• Habits like alcohol or intense exercise may affect results, so follow your provider's prep instructions.

• Ask whether to fast. It isn't always required, but some paired tests call for it.

Reference ranges differ from lab to lab, so the same result can read as normal on one report and borderline on another. That is why reference ranges vary by lab, and why your symptoms belong in the read.

How to read your FSH, LH, and testosterone results

The pattern across all three hormones helps point to a cause. Guidelines support a low-testosterone diagnosis with a threshold, but the number alone doesn't define it; a provider weighs it with symptoms and repeat morning testing, then measures LH to sort out why (Mulhall et al., 2018). LH and FSH then split the picture into two broad patterns that overlap and need a provider's read.

A man with low testosterone and normal LH sits in a gray zone, which is why low testosterone with normal LH is its own conversation. The form of testosterone matters too. Most testosterone is bound to proteins like SHBG, so when SHBG runs high or low, free and total testosterone can tell different stories, and a clinician may check free testosterone.

Why pair hormone testing with a semen analysis?

Hormones explain the why; a semen analysis measures the what. The blood test shows whether your signaling and testosterone are in range, while a semen analysis looks at the output: sperm concentration, movement, and shape. When sperm numbers are low and the hormone pattern is off, the two together can point to where along the brain-to-testes pathway the problem sits. That pairing also helps separate diagnosed hypogonadism from a potentially treatable signaling issue.

Does testosterone therapy hurt fertility?

Often, yes, and this surprises men most. Taking testosterone from outside the body, whether prescribed or as anabolic steroid use, usually suppresses the brain's LH and FSH signals. Without them, the testes typically slow sperm production and can shrink. Testosterone therapy is not a fertility treatment; for a man hoping to conceive soon, it's worth weighing other options with a provider first.

Recovery varies. Sperm production usually returns after stopping, but the timeline is unpredictable and a full return isn't guaranteed, so fertility belongs in the conversation before starting.

There are ways to help preserve fertility while treating low testosterone. Providers may add hCG, which mimics LH and keeps the testes active, as covered in hCG alongside testosterone. Others use clomiphene or enclomiphene, which raise the body's own LH and FSH; enclomiphene for secondary hypogonadism is one route. Several are used off-label and belong under a clinician's direction. Men already on therapy can read about maintaining fertility on testosterone therapy.

Testosterone is a monitored medical therapy, not a treatment for normal aging. The FDA approves it for diagnosed hypogonadism, not for low testosterone due to aging alone, and in 2025 it removed the boxed cardiovascular warning while adding a blood-pressure warning (FDA, 2025). That followed the TRAVERSE trial, which found testosterone noninferior to placebo for major cardiac events but reported higher rates of atrial fibrillation and pulmonary embolism (Lincoff et al., 2023). As a Schedule III medication, it requires a prescription after evaluation and lab confirmation, where state law allows.

What your results mean for your next step

FSH, LH, and testosterone work best read as a set. Any single value can mislead, but the pattern across all three tells a clinician where to look next. If you're planning a family or weighing testosterone therapy, start with a morning blood draw, add a semen analysis when fertility is the question, and have a clinician read the full pattern alongside your history. That's how a hormone result becomes a clear next step instead of guesswork.

Disclaimer: This blog post is intended for informational purposes only and should not be considered medical advice. Always consult a healthcare professional before making changes to your health routine.

FAQs

What do FSH, LH, and testosterone reveal about male fertility? 

FSH, LH, and testosterone reveal where a fertility problem starts along the path from the brain to the testes. FSH reflects the signal for sperm production, LH reflects the signal for testosterone, and testosterone shows the testes' output. Read as a pattern, they separate a testicular cause from a pituitary or hypothalamic one.

What is a normal testosterone level for fertility? 

There isn't a single testosterone 'fertility number.' A blood testosterone level reflects the risk of deficiency, not sperm production, and a provider reads it with your symptoms and repeat morning testing rather than a single value (Mulhall et al., 2018). A normal testosterone does not rule out a fertility problem, which is why a semen analysis is used to assess fertility.

Can you have normal testosterone but still be infertile? 

Yes. Testosterone in the bloodstream can look normal while sperm production is low, since sperm depend on high testosterone concentrations inside the testicle and on adequate FSH. This is why a semen analysis is run alongside hormones when fertility is the concern.

What do high FSH and LH mean in men? 

High LH and FSH alongside low testosterone usually point to primary hypogonadism, meaning the testes are not responding to a strong signal from the brain. Low or normal LH and FSH with low testosterone point to a secondary cause in the pituitary or hypothalamus. Measuring LH is how the AUA separates these two patterns (Mulhall et al., 2018).

Does testosterone therapy cause infertility? 

It can. External testosterone suppresses the brain's LH and FSH, which the testes need to make sperm, so standard testosterone therapy often lowers fertility. Suppression varies between men and is not guaranteed to fully reverse, and the FDA approves testosterone for diagnosed hypogonadism, not for low testosterone due to aging alone (FDA, 2025). Men who want to preserve fertility should raise this with a clinician before starting.

How should you prepare for an FSH, LH, and testosterone test? 

Schedule the draw for early morning, when testosterone peaks, and expect to repeat it on a second morning, since the AUA calls for two morning measurements (Mulhall et al., 2018). Tell your clinician about every medication and supplement, including any hormone products, and ask whether to fast. Avoid heavy training and alcohol the day before.

Is a hormone test enough, or do you also need a semen analysis? 

For fertility questions, usually both. Hormones show whether the signaling and testosterone levels are in range, while a semen analysis measures sperm count, movement, and shape directly. Together they show where a problem sits; one without the other can miss the cause.

References

• Endocrine Society. Hypogonadism in men.

• FDA. Class-wide labeling changes for testosterone products. 2025.

• J Clin Endocrinol Metab. 2018;103(5):1715-1744

• J Urol. 2018;200(2):423-432

• N Engl J Med. 2023;389(2):107-117