“Inhibin: The Missing Hormone No One Talks About — And Why Your ‘Low Estrogen’ Lab Might Be Misleading”

Womens HealthHormones

Dec 21

Written By Bello Wellness

Across Ontario — especially in the Durham Region, Pickering, and Ajax — thousands of women are told every year:

“Your estrogen is low. You’re entering menopause.”

But here’s the physiology most women are never told:

In perimenopause, the first hormone to fall isn’t estrogen — it’s inhibin.

And that single shift changes everything.

1. Inhibin drops first — not estrogen.

In early perimenopause, the ovaries gradually produce less inhibin, the hormone that normally keeps FSH (follicle-stimulating hormone) steady.

When inhibin falls:
✔ FSH rises
✔ The ovary becomes harder to regulate
✔ Estradiol becomes chaotic, not consistently low

This instability — not estrogen deficiency — defines early perimenopause for many Ontario women.

“Inhibin” - H.M Fraser. Clinical Endocrinology. 1988. https://pubmed.ncbi.nlm.nih.gov/3282246/

2. Low estrogen labs are often misinterpreted.

A single estrogen blood test can show:

low estradiol
normal estradiol
or very high estradiol

…depending on the week, sleep, stress, cycle timing, and inhibin/FSH activity.

So when a woman in Pickering or Toronto is told:

“You’re menopausal because your estrogen is low,”

…it’s often incomplete or inaccurate — especially if she still has cycles.

Estradiol in perimenopause is volatile, not consistently low.

3. Why getting estrogen levels checked can create confusion.

Estradiol can rise or fall tenfold in a week during perimenopause.

So a single lab value rarely tells the whole story — especially if inhibin and progesterone are shifting at the same time.

Women across Ontario often report being misclassified based on one lab.

4. The real culprit behind hot flashes + night sweats?

It’s not low estrogen — it’s inhibin loss, triggering elevated FSH and unpredictable estrogen signaling.

Chain reaction:
inhibin↓ → FSH↑ → estrogen instability → vasomotor symptoms

Understanding this prevents unnecessary fear — and unnecessary misdiagnoses.

“Vasomotor Symptoms: Natural History, Physiology, and Links with Cardiovascular Health” — Thurston RC. Climacteric. 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC5902802/

5. Why this matters for treatment.

Your symptoms may stem from:

inhibin decline
FSH elevation
estrogen volatility
progesterone drop
thyroid changes
cortisol dysregulation
metabolic factors

Not one variable — but the interaction between them.

This is why treatment should never be template-based.
It must be individualized, based on physiology.

TAKEAWAY

If you’ve been told you're “menopausal” because of one low estrogen reading, you're not alone.

Perimenopause is complex — and your care deserves to reflect that complexity.

A hormone specialist can help you understand what’s truly driving your symptoms so you can move forward with clarity, confidence, and evidence.

Bello Wellness — restoring what your body already knows how to do.

This material is for educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional for individual care.