Clinician reference tool — not medical advice. This is a clinical decision-aid intended for healthcare professionals: it gives deterministic suggestions to think with, not a diagnosis or a prescription. If you’re a patient, you’re welcome to look around — but please review anything here with your own doctor; it isn’t a substitute for personalized medical care.
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Progesterone (including 'day 21 progesterone')

Sex hormones · specimen: blood

Indicated in specific situations

Also called: day 21 progesterone, mid-luteal progesterone, serum progesterone, progesterone level

Chart note

Pick Ordered or Not ordered to see the note.

Indicated when

  • Confirming ovulation as part of a fertility work-up, measured in the mid-luteal phase (day 21 of a 28-day cycle, or adjusted for cycle length) [1]

Not indicated when

  • Routine hormone panels to diagnose perimenopause or menopause, alongside estradiol/FSH/LH [2]
  • Diagnosing 'estrogen dominance' or general hormone 'imbalance' outside a fertility work-up, since no validated reference range for this use exists

Why not

Outside a fertility work-up, a single progesterone level does not have a validated role: guidelines that address hormone testing in menopause specifically advise against routinely ordering progesterone alongside estradiol, FSH and LH [2]. Progesterone also varies through the cycle, so a level taken without regard to cycle timing is hard to interpret and can be mistakenly read as 'low' when it simply wasn't drawn in the luteal phase.

Better first step

If the question is ovulation or fertility, time the test to the mid-luteal phase (about 7 days before the next expected period) as part of a proper fertility assessment [1]. If the question is perimenopausal symptoms, diagnose from history and menstrual pattern rather than a hormone panel.

Typical ND rationale

An ND may order progesterone, sometimes labelled 'day 21 progesterone' even outside a fertility context, as part of a broader hormone panel to assess an estrogen-to-progesterone ratio or 'hormone balance,' reasoning that low progesterone could explain symptoms such as PMS, mood changes, or heavy or irregular periods.

Where the ND is right

The ND is right that day 21 (mid-luteal) progesterone is a real, guideline-recommended test for confirming ovulation in women being investigated for fertility, and it should be timed to the luteal phase, not a fixed calendar date, in women with irregular cycles [1]. Where the evidence does not support progesterone testing is diagnosing perimenopause, menopause, or 'hormone imbalance' outside that fertility context.

Ontario coverage & CONO orderability

OHIP status
insured
Progesterone (L331) is listed by name in the 2026 Schedule of Benefits for Laboratory Services with no restricting condition noted, so it is insured when a physician orders it after clinically assessing the patient (Reg. 552 s.22). ND-ordered testing is patient-paid regardless [5].
CONO orderable
Yes — CONO list #102, #161, #181
CONO list item 102 (blood), 161 (urine) and 181 (saliva), all 'Progesterone.'

Linked conditions

Counselling script

“If we're checking whether you're ovulating for a fertility work-up, progesterone timed to about a week before your period is the right test, and I'm happy to order it that way. As a general hormone-balance check outside that context, it's not reliable enough to interpret, since the level changes so much through your cycle. Let's be specific about what we're trying to answer first.”

Revisit if

  • Patient is or becomes actively trying to conceive and ovulation status is in question
  • Menstrual cycle pattern changes significantly

References

  1. [1]NICE (2024). Fertility problems: assessment and treatment (NG257, formerly CG156) — investigation of fertility problems. linkOffer a mid-luteal (day 21 of a 28-day cycle) serum progesterone to confirm ovulation in people investigated for fertility problems; time to cycle length if irregular
  2. [2]Society of Obstetricians and Gynaecologists of Canada / Choosing Wisely Canada (2021). Obstetrics and Gynaecology recommendations. linkDon't routinely order hormone levels including progesterone, estradiol, FSH and LH in postmenopausal women or after a hysterectomy
  3. [3]Ontario Ministry of Health (2026). Schedule of Benefits for Laboratory Services (effective April 1, 2026) — L331 Progesterone. linkProgesterone (L331) listed in the 2026 OHIP Schedule of Benefits for Laboratory Services
  4. [4]Government of Ontario (e-Laws) (2026). Health Insurance Act, R.R.O. 1990, Reg. 552: General, s. 22 (insured laboratory services). linkA lab test is insured only when ordered by a physician, midwife, or NP who has clinically assessed the patient
  5. [5]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services
Evidence notes

NICE's day-21/mid-luteal progesterone recommendation was originally issued in CG156 (2004, amended 2013) and is carried forward unchanged in the current NG257 fertility guideline; flagged for age of the underlying recommendation even though the guideline itself remains current and was reissued. Linking to 'pcos' reflects that anovulation is a core PCOS feature and progesterone is sometimes used to assess it, not that progesterone diagnoses PCOS itself. Reviewer: removed a numeric ovulation threshold (30 nmol/L) from the chart snippet. It is not stated in NICE NG257 as fetched, and lab-specific interpretive ranges apply. Added NG257 1.18.8 (irregular cycles: test later and repeat weekly).