Hypothalamic Amenorrhea vs PCOS: Why Your Blood Tests Hold the Clues

Missing periods? You’ll often hear two diagnoses thrown around — PCOS and Hypothalamic Amenorrhea (HA) — but the treatment paths for these two couldn’t be more different.
The problem? They can look similar from the outside — irregular or absent periods — but your blood work can reveal exactly which one you’re dealing with.

What is Hypothalamic Amenorrhea (HA)?

HA happens when your brain reduces the hormonal signals to your ovaries.
Common triggers:

• Low body fat

• Over-exercising

• Significant calorie restriction

• High physical or emotional stress

Your hypothalamus essentially says: “This isn’t a safe time to reproduce.”

Blood work patterns in HA:

• FSH & LH: Both low (often LH is not significantly higher than FSH)

• Oestrogen: Low

• Testosterone: Low

• DHEA: Low

• Cortisol: Possibly high (due to chronic stress)

• Insulin: Usually normal

What is Polycystic Ovary Syndrome (PCOS)?

PCOS is a metabolic and hormonal condition where ovulation is irregular or absent due to a different mechanism — often related to insulin resistance, inflammation, and excess androgen production.

Blood work patterns in PCOS:

• LH: High — often roughly double FSH (even if both are in the “normal” lab range).
  Example: FSH = 4 IU/L, LH = 8 IU/L → This is considered an “elevated LH:FSH ratio.”

• Testosterone: High. Anything greater than 1.3.

• DHEA: High. Anything greater than 6.

• Cortisol: Often high

• Insulin: High or high-normal

• Oestrogen: Can be normal or high

Key Difference in Labs:

Marker HA PCOS
FSH Low Normal/low

LH Low High (often 2× FSH)

Oestrogen Low Normal/high

Testosterone Low High

DHEA Low High

Cortisol Normal/high High

Insulin Normal High

Why This Matters

Treating HA like PCOS (or vice versa) can make the problem worse.

• HA: Needs stress reduction, increased calorie intake, lighter exercise, and restoring energy balance.

• PCOS: Needs blood sugar regulation, androgen management, and ovulation support.

Final Takeaway:

Your symptoms are only part of the story. The real answers are in your blood work — and interpreting them through the lens of optimal ranges (not just “in range”) is key.

That’s exactly why I created my Hormone Blood Testing Guide — a 60-page resource showing you:

• Exactly which hormones to test (and when in your cycle)

• The optimal ranges for each marker (not just “in range”)

• How to start piecing together what your results actually mean

If you’ve been told your missing periods are “just PCOS” or “just stress” but you’re not convinced, this guide will give you the knowledge to ask the right questions — and finally get clear answers.

📥 Grab your copy here → Hormone Blood Testing Guide