LH & FSH
Pituitary gonadotropins. LH signals the testes to produce testosterone (or triggers ovulation); FSH drives sperm production (or follicle development).
These two separate primary from secondary hypogonadism — which completely changes the treatment path. They're also the first values to hit zero on exogenous testosterone, making them the fertility marker.
The plan of attack
In this order. Most people start at step four, which is why they change five things at once and learn nothing.
- Confirm the number is real
Pulsatile secretion. LH is released in pulses every 60–90 minutes, so a single draw catches a random point on a wave. Two samples an hour apart can differ substantially. For an important decision, pooled or repeated sampling is more reliable than one value. - Read it with its partner
Anyone on TRT who wants children later should have baseline LH/FSH and a semen analysis before starting. Recovery post-TRT is not guaranteed and takes months. Draw it alongside: Total Testosterone, Prolactin, Estradiol, Standard (ECLIA). - Work out which direction is yours
If it's high — In women, elevated FSH signals diminishing ovarian reserve/perimenopause. In men, it means the testes aren't responding to signal.
If it's low — Suppressed axis — most commonly exogenous testosterone, but also opioids, high prolactin, or severe under-eating (relative energy deficiency). - Fix it in this order
Nutrition. Restore energy availability — relative energy deficiency (RED-S) suppresses the entire HPG axis in both sexes and is dramatically under-recognized in lean, hard-training people.
Lifestyle. Reduce training volume if over-trained, restore body fat to a healthy range, sleep, and taper off opioids where applicable.
Supplements. No supplement meaningfully raises LH/FSH. Correct vitamin D and zinc as general support.
Hormones. Enclomiphene or clomiphene (SERMs) raise endogenous LH/FSH and testosterone while preserving fertility. hCG substitutes for LH directly. Both under medical supervision.
Compounds. hCG mimics LH; gonadorelin pulses stimulate pituitary LH/FSH release — used on TRT to maintain testicular volume and fertility. Kisspeptin is an emerging upstream option in research settings.
Work down the list, not across it. Adding a compound on top of an unfixed diet is why generic protocols fail. - Retest
Baseline before TRT; when investigating low T; when planning fertility. Change one thing at a time, or the retest can't tell you which thing worked.
How to fix it
📚 Endocrine Society CPG — Testosterone Therapy in Men with Hypogonadism (diagnostic algorithm).
🩸 Test your LH & FSH
Order directly through Marek Diagnostics — no doctor's visit needed, drawn at any Quest location in the US. Code CAMERON applies 10% off automatically.
Order this test — 10% off → Browse all 102 markers →What LH & FSH is usually tested alongside
On its own, one marker is a data point. These panels include LH & FSH plus the markers that make it interpretable — each names every test, why it is on the list, and loads the whole set into your cart in one click at 10% off.
includes this + 10 more markers · built for men — Fatigue, low libido, poor recovery, mood or body composition changes — and you're considering TRT. Read this before you start.
includes this + 8 more markers · built for men — Coming off a cycle, running PCT, or checking whether your natural production actually recovered.
includes this + 9 more markers · built for women — Planning a pregnancy, actively trying, or wanting to understand your ovarian reserve before making decisions about timing.
includes this + 10 more markers · built for women — Anywhere from late 30s onward with cycle changes, night sweats, sleep disruption, mood shifts, joint aches, brain fog, or a libido that fell off a cliff.
What moves your LH & FSH
8 compounds and 2 supplements in the Vault have a documented effect on this marker, or are a reason to have measured it first:
Browse all 237 compounds & 350 supplements →
Would you feel it? Symptoms LH & FSH helps explain
People rarely search for a marker — they search for how they feel. These are the complaints where this marker is worth checking, and whether it is a first-line test or a follow-up once the obvious causes are ruled out.
Why your LH & FSH might be wrong
Most abnormal results are interference, not disease. These are the things that measurably move this specific marker — check them before you change anything. Each one says whether the number is wrong and should be repeated, badly timed and should be redrawn, or real with a cause worth explaining.
LH is released in pulses every 60–90 minutes, so a single draw catches a random point on a wave. Two samples an hour apart can differ substantially.
For an important decision, pooled or repeated sampling is more reliable than one value.
Varies severalfold across a normal cycle, so a result without a cycle day attached is close to uninterpretable.
Note the cycle day. Day 3 for the follicular baseline; seven days after ovulation for the luteal phase.
All suppress LH and FSH through negative feedback — often to undetectable. That is expected, not a pituitary problem.
A suppressed LH on TRT is the drug. It tells you nothing about your own axis until you stop.
What LH & FSH means in combination
A single marker tells you a little. Combinations tell you the story — these are the named patterns this marker takes part in, and what each one points at.
Three completely different diagnoses that present identically, distinguished by one pairing. Low-with-low means the axis was switched off centrally — almost always energy availability. High FSH means the ovary is failing and the pituitary is shouting. A raised LH:FSH ratio with androgens points at PCOS.
Exclude pregnancy first, always. Low-with-low goes to the RED-S protocol; high FSH needs proper assessment; PCOS has its own panel. Prolactin belongs in all three workups because it is treatable.
A high early-follicular oestradiol suppresses FSH through negative feedback, so a diminishing ovarian reserve can hide behind a normal-looking FSH. This is the specific reason both are drawn together on day three rather than FSH alone.
Never interpret a day-3 FSH without the oestradiol beside it. If oestradiol is raised, the FSH is not interpretable and the draw should be repeated in a subsequent cycle.
What to test next
Markers rarely answer alone. These are the ones that put LH & FSH in context — each with its own full breakdown.
Frequently asked questions
LH 1.7–8.6 mIU/mL · FSH 1.5–12.4 mIU/mL Ranges vary by laboratory and assay — always compare to the range printed on your own report.
Within range alongside healthy testosterone = intact axis. The pattern matters more than the absolute number.
In women, elevated FSH signals diminishing ovarian reserve/perimenopause. In men, it means the testes aren't responding to signal.
Suppressed axis — most commonly exogenous testosterone, but also opioids, high prolactin, or severe under-eating (relative energy deficiency).
You can order LH & FSH directly through Marek Diagnostics without a doctor's visit — drawn at any Quest Diagnostics location in the US. Code CAMERON applies 10% off automatically.