We can’t count how many times women come to us and say:
“My doctor said everything looks normal… but I still can’t get pregnant.”

Here’s the truth:
➡️ “Normal” isn’t the same as optimal​
➡️ And most standard labs don’t tell the full fertility story

Today we’re breaking down 5 of the most commonly misunderstood labs — and how to interpret them through a functional lens.

1. TSH vs. Free T3 & Free T4

Your thyroid controls your metabolism, hormone production, ovulation, and even implantation. Most doctors only run TSH (thyroid stimulating hormone), but that’s not enough.

Why it matters:

• TSH is a brain signal — it doesn’t tell us if the thyroid is actually making or converting hormones well
• Free T3 is your active thyroid hormone — it’s what drives energy, egg development, and ovulation
• Free T4 is your storage form — which has to convert into T3

What we look for:

• TSH between 0.5–2.0 for optimal fertility
• Free T3 3.2 and higher
• Free T4 1.4-1.8
• Symptoms like cold hands/feet, fatigue, constipation, or long cycles — even with “normal” labs

Mineral tie-ins: Selenium and zinc support thyroid hormone conversion. Low sodium or adrenal dysfunction can also drive high or erratic TSH.

2. Progesterone

Progesterone is essential for ovulation, implantation, and sustaining a pregnancy. And it’s one of the most poorly timed labs out there.

Why it matters:

• You need a strong post-ovulation surge of progesterone to hold the uterine lining and support early pregnancy
• Most women test on day 21 — but if you ovulate late (common with PCOS or stress), that number may be meaningless

What we look for:

• Test ~7 days after ovulation (use BBT or LH strips to confirm)
• Ideally above 10 ng/mL for fertility support
• Symptoms like spotting, anxiety, PMS, short luteal phase, or insomnia

Mineral tie-ins: Magnesium, vitamin B6, and cholesterol are needed to produce progesterone. Adrenals and thyroid also play a huge role.

3. The Iron Panel (Not Just Ferritin)

Iron is critical for egg maturation, ovulation, and energy — but both low and high levels can impact fertility.

Why it matters:

• Low iron (especially low ferritin) can lead to anovulation, poor egg quality, fatigue, and short luteal phases
• High iron can trigger oxidative stress, inflammation, and even suppress ovulation (mimics PCOS symptoms)

What we look for:

• Ferritin between 40-60 ng/mL
• Iron saturation 25-35% , serum iron of about 100 μg/dL
• Pair with copper and zinc from HTMA for a full picture

Food-first approach: If iron is low, we look at gut health, stomach acid, copper status, and food sources — not just supplements.

4. FSH (Follicle-Stimulating Hormone)

FSH is the signal from your brain that tells your ovaries to start growing follicles. It’s best tested on cycle day 2–3.

Why it matters:

• High FSH can mean your ovaries aren’t responding well — often tied to low egg reserve or poor communication
• Low or suppressed FSH may indicate HPA axis dysfunction or overtraining

What we look for:

• A value under 10 on day 3 is generally considered good
• We compare it to LH for insight into ovarian reserve vs. PCOS
• We look at patterns over 3–6 months — one number doesn’t tell the whole story

Mineral tie-ins: Sodium, zinc, and potassium all support follicle development and brain-ovary communication.

5. Estradiol (E2)

Estradiol is your main estrogen and plays a huge role in growing the uterine lining and maturing the egg.

Why it matters:

• Too low = poor follicle development and thin uterine lining
• Too high = possible estrogen dominance (especially if progesterone is low)

What we look for:

• Estradiol between 25–75 pg/mL on day 3
• A healthy mid-cycle rise (around day 12–13)
• Balanced with progesterone in the luteal phase

Detox and mineral tie-ins: Estrogen clearance depends on your gut, liver, bile flow, and minerals like magnesium and molybdenum.

Here’s the big takeaway:

Don’t settle for “everything looks fine.”
Fertility is complex, and your labs deserve to be interpreted in context.

In Part 3 of this series, we’ll share:
​How to Advocate for Better Labs — and What to Do If Your Doctor Won’t Run Them

You deserve more than normal.
You deserve answers.

If you want to learn more about how to prioritize testing when it comes to fertility, check out this blog post!

reminder: i’m currently accepting people into my Nurture Your Fertility program. you can learn more here about the program and fill out an application!