🧬 Understanding FSH, LH, Estrogen & Progesterone Across Perimenopause and Menopause

Hormone levels help paint a picture — but it’s not a single snapshot. It’s more like tracking a stormy weather pattern. 

Estrogen is a key hormone that supports brain, bone, heart, skin, and vaginal health — but it also powerfully affects how we feel. It helps regulate mood, energy, memory, and sleep, and boosts levels of serotonin and dopamine (the brain’s feel-good and motivation chemicals). When estrogen levels are steady, many people feel more emotionally balanced, clear-headed, and energetic. But when it fluctuates or drops — like in perimenopause — it can trigger mood swings, low motivation, anxiety, poor sleep, and brain fog. Estrogen isn't just about reproduction — it’s a whole-body, whole-self hormone.

🌪 Perimenopause (the transition phase):

FSH & LH: Can be low, normal, or high — they fluctuate a lot.

Estrogen (E): Also fluctuates wildly — can be low one day, high the next.

It’s still being produced by the ovaries — but not consistently.

Progesterone (P): Usually low or absent, especially in later perimenopause, because ovulation becomes infrequent or stops.

Bleeding: May be irregular, heavy, light, or absent (especially with Mirena or after hysterectomy).

➤ If FSH and LH are high, and estrogen is still high, you're still cycling sporadically — that’s late perimenopause, not menopause.

🛑 Menopause (when ovaries retire):

FSH & LH: Stay consistently high — your brain keeps signalling, but the ovaries no longer respond.

Estrogen: Falls and stays low, because the ovaries no longer make much.

Progesterone: Also remains low, as ovulation has ceased.

No periods: Defined as 12 months without a natural period (which we can’t track if Mirena or hysterectomy is present, so we rely on other signs).

🧩 So what does it mean when…

✅ High FSH/LH + Some Estrogen?

👉 Likely late perimenopause. Your brain is signalling strongly, but your ovaries still fire intermittently.

✅ High FSH/LH + no Estrogen?

👉 Could be menopause, or late perimenopause. Especially likely menopause if this pattern is stable over time.

✅ Low FSH/LH + Some Estrogen?

👉 Fits early or mid-perimenopause, when hormones fluctuate and the cycle is still (quietly) active.

✅ No Progesterone?

👉 Common across both perimenopause and menopause, since ovulation becomes rare or stops completely.

🧠 Why This Matters:

Diagnosing menopause under 40 is REALLY important.  Because primary ovarian insufficiency leads to many negative health consequences and hormone therapy is recommended.  Menopause under 45 also has some health risks, and is called early menopause.  HRT is recommended here too.

But as you can see...

Hormone testing can help, but it's not definitive, especially if you're not bleeding (e.g., due to Mirena or hysterectomy). We interpret bloods in context — with:

• Your age and symptom pattern
• Whether hormone levels are stable or fluctuating
• How you respond to treatment or support