Low Progesterone? Here’s How to Test It the Right Way
If you suspect low progesterone might be behind your symptoms—like spotting before your period, a short luteal phase, mood swings, or trouble conceiving—you’re probably wondering how to actually test for it.
The truth? Most women are told to “check it on day 21,” but this doesn’t work for everyone—and could lead to missing a true deficiency altogether.
Let’s walk through how to test your progesterone the right way, what your levels should look like, and the best functional options if you want to go deeper.
LOW PROGESTERONE?
✨ Why Test Progesterone?
Progesterone is the hormone of the luteal phase—produced only after ovulation—and it’s essential for:
Holding the uterine lining in place
Supporting implantation and early pregnancy
Balancing out estrogen to prevent PMS and inflammation
If levels are too low (or drop too early), it can result in:
Spotting before your period
A short luteal phase
Trouble staying pregnant
PMS symptoms like mood swings, anxiety, and insomnia
⏰ When to Test Progesterone (It’s Not Always Day 21)
Most women are told to test progesterone on cycle day 21, assuming they ovulate on day 14. But if you ovulate early or late, this timing won’t reflect your true levels.
✅ The right time to test is:
7 days after ovulation — not a specific cycle day.
So, if you ovulate on:
Day 14 → test on Day 21
Day 18 → test on Day 25
Day 12 → test on Day 19
Track ovulation using LH strips, BBT charting, or a fertility tracker to find your specific window.
Want to test your hormones at home? I offer comprehensive labs + interpretation—learn more here.
🔬 Best Ways to Test Progesterone
1. Blood Test (Serum Progesterone)
This is the most common way to test. Progesterone peaks mid-luteal phase and should be:
Above 10 ng/mL for fertility support
Levels between 5–10 ng/mL may indicate insufficiency
Below 5 ng/mL suggests very low production or no ovulation
📌 Note: One-time serum tests show a snapshot. If your timing is off, the results may not reflect your true production.
2. DUTCH Test (Dried Urine Test for Comprehensive Hormones)
This functional test measures progesterone metabolites (like Pg or b-Pg), which show how your body is making and metabolizing progesterone over time.
DUTCH is helpful if you want to look at:
Overall progesterone patterns (not just a single moment)
Estrogen + cortisol balance at the same time
How your body is processing hormones, not just producing them
Great for a deeper dive if you’re dealing with PMS, fatigue, mood issues, or TTC struggles.
3. BBT Tracking (Basal Body Temperature)
BBT doesn’t give you a number, but it offers insight into whether you’re ovulating and sustaining progesterone.
After ovulation, progesterone raises your resting temp by 0.5–1°F.
A slow rise or early drop can indicate weak ovulation or low progesterone.
A short luteal phase (<10 days) often reflects a deficiency.
Combine this with serum or DUTCH testing for a fuller picture.
4. Saliva Testing (Less Common)
Some practitioners use saliva to measure free hormones, but it’s more commonly used in adrenal testing than for evaluating progesterone accurately. Blood and DUTCH tend to offer more clinically relevant data.
🧪 What If You Want a Full Picture?
If you suspect progesterone issues, it's rarely just about progesterone. Other helpful labs include:
FSH, LH, and estradiol (to assess ovulatory patterns)
Prolactin (high levels can suppress ovulation)
Thyroid panel (low thyroid function can impact hormone production)
Vitamin D, insulin, and blood sugar markers
GI MAP → If gut inflammation or microbiome imbalances are impacting estrogen metabolism
HTMA → If stress and mineral depletion are affecting ovulation and hormone output
Final Thoughts
Testing progesterone the right way can give you real answers—whether you’re trying to conceive, struggling with PMS, or just want more stable, symptom-free cycles. Don’t let outdated advice like “test on day 21” lead you astray. Ovulation tracking + the right lab test = clarity and direction.
👉 Ready to test your hormones and build a cycle-supportive plan?
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