Women's Hormone Health: What Your Blood Tests Can Tell You

You're exhausted despite sleeping eight hours. Your anxiety has appeared from nowhere. Your periods have become unpredictable, and your brain feels like it's operating through fog. Your GP runs a "standard" blood test and tells you everything is normal.

But everything doesn't feel normal. That disconnect between how you feel and what basic tests show is one of the most frustrating experiences in women's healthcare.

The truth is, standard blood tests often don't include the hormone markers that explain your symptoms. A comprehensive hormone panel can reveal what's actually happening — and what you can do about it.

Why Hormones Matter

Hormones regulate virtually everything: energy, mood, sleep, weight, skin health, bone density, cardiovascular protection, and cognitive function. When hormones shift — as they naturally do across your lifetime — the effects are felt everywhere.

What makes female hormonal health particularly complex is that it's inherently cyclical. Women's hormones fluctuate across the menstrual cycle, shift dramatically during pregnancy, and undergo fundamental changes during perimenopause and menopause. This means when you test is almost as important as what you test.

Practical takeaway: Hormone blood tests are most informative when timed correctly within your cycle. A random oestradiol level without knowing where you are in your cycle is of limited value.

Oestradiol and Progesterone

Oestradiol (the primary active form of oestrogen) is arguably the most important hormone in women's health. It protects your cardiovascular system, maintains bone density, supports cognitive function, regulates mood via serotonin pathways, and keeps skin, hair, and mucous membranes healthy.

Oestradiol levels vary dramatically across the menstrual cycle:

• Early follicular phase (days 2–5): 110–400 pmol/L — this is the best time for a "baseline" reading
• Mid-cycle (ovulation): peaks at 400–1,500 pmol/L
• Luteal phase: 200–800 pmol/L
• Post-menopause: typically below 100 pmol/L

Progesterone is oestradiol's essential partner. Produced primarily after ovulation by the corpus luteum, progesterone calms the nervous system, supports sleep, prepares the uterine lining for implantation, and counterbalances oestrogen's stimulatory effects.

• Follicular phase: below 5 nmol/L (progesterone is minimal before ovulation)
• Mid-luteal phase (day 21 of a 28-day cycle): above 30 nmol/L confirms ovulation
• Post-menopause: below 1 nmol/L

Declining progesterone is often the first hormonal change women notice in their late thirties and early forties. Shorter luteal phases, increased pre-menstrual anxiety, disrupted sleep in the second half of the cycle, and heavier periods can all result from falling progesterone — even while oestradiol remains normal.

Practical takeaway: If you're investigating cycle-related symptoms, test oestradiol on days 2–5 of your cycle and progesterone on day 21 (or 7 days after ovulation if your cycle is longer). The combination reveals whether you're ovulating and whether your progesterone response is adequate.

FSH and LH

FSH (follicle-stimulating hormone) and LH (luteinising hormone) are the pituitary hormones that orchestrate your menstrual cycle — essential for understanding fertility, cycle regularity, and menopausal transition.

• FSH stimulates ovarian follicle development. Normal early follicular range is 3–10 IU/L. Rising FSH (above 10–12 IU/L) is one of the earliest signs of declining ovarian reserve
• LH triggers ovulation, with a mid-cycle surge reaching 20–60 IU/L. In PCOS, LH is often chronically elevated relative to FSH (LH:FSH ratio greater than 2:1)

According to the NICE guidelines on menopause (NG23), FSH testing is not recommended for diagnosing menopause in women over 45 with typical symptoms, because FSH fluctuates widely during perimenopause. However, it is recommended for women under 40 with suspected premature ovarian insufficiency and for women aged 40–45 where diagnosis is uncertain.

Practical takeaway: FSH is most useful as a trend over time. If you're under 45 with possible perimenopausal symptoms, test FSH on days 2–5 of your cycle on two separate occasions, several weeks apart.

Thyroid: The Overlooked Hormone

Thyroid dysfunction is five to eight times more common in women than men, according to the British Thyroid Foundation. It's frequently missed because thyroid symptoms — fatigue, weight gain, brain fog, mood changes, hair loss — overlap with hormonal changes and "normal ageing."

The essential thyroid markers are:

• TSH — the screening test. Normal is 0.4–4.0 mIU/L, but symptoms often emerge above 2.5 mIU/L
• Free T4 — the main circulating thyroid hormone. Normal is 12–22 pmol/L
• Free T3 — the active form (3.1–6.8 pmol/L). Some women convert T4 to T3 poorly, resulting in normal TSH but persistent symptoms
• Thyroid antibodies (TPO and TG) — detect Hashimoto's thyroiditis, often elevated years before TSH becomes abnormal

Thyroid health and reproductive hormones are deeply interconnected. Hypothyroidism can cause irregular periods, heavy bleeding, infertility, and recurrent miscarriage. Oestrogen affects thyroid-binding globulin, meaning hormonal changes during pregnancy, perimenopause, and HRT alter thyroid test interpretation.

Practical takeaway: Every woman with fatigue, unexplained weight changes, or cycle irregularity should have a full thyroid panel — not just TSH. Free T3 and thyroid antibodies may reveal what TSH alone misses.

SHBG, DHEA-S, and Cortisol

These three markers provide crucial context that standard panels often omit.

SHBG (sex hormone-binding globulin) binds oestradiol and testosterone, rendering them inactive. High SHBG reduces the hormone available to your tissues even if total levels appear normal. Normal range is approximately 20–130 nmol/L. SHBG rises with age, oral contraceptives, and hyperthyroidism; it falls with obesity, insulin resistance, and PCOS.

• High SHBG — may explain symptoms of hormone deficiency despite "normal" total levels
• Low SHBG — associated with insulin resistance and excess androgen effects (acne, hair thinning, hirsutism)

DHEA-S is an adrenal precursor to both oestrogen and testosterone. It declines steadily from the late twenties. Low DHEA-S is linked to fatigue, reduced immunity, and low libido.

Cortisol — chronic elevation suppresses reproductive hormones, disrupts thyroid function, and promotes visceral fat. Morning cortisol ideally sits between 200–500 nmol/L (measured 8–10am).

Practical takeaway: If your main hormones look "normal" but you still have symptoms, SHBG, DHEA-S, and cortisol often reveal the hidden context.

Hormones at Every Life Stage

The hormones that matter most — and their typical patterns — shift across your lifetime. This table provides a framework for understanding what to prioritise at each stage:

Life Stage	Key Hormones to Test	What to Look For
20s	Oestradiol, progesterone, thyroid, vitamin D	Cycle regularity, baseline values, PCOS screening if symptomatic
30s	Add FSH, AMH (if fertility is relevant), DHEA-S	Early ovarian reserve changes, rising FSH, progesterone adequacy
40s	Full panel: oestradiol, progesterone, FSH, LH, thyroid, SHBG, DHEA-S, cortisol	Perimenopausal changes, erratic cycles, emerging thyroid dysfunction
50s+	Oestradiol, FSH, thyroid, SHBG, vitamin D, HbA1c, cardiovascular markers	Post-menopausal hormone levels, cardiovascular and metabolic risk, bone health markers

Practical takeaway: Your testing priorities should evolve with your life stage. A 25-year-old investigating irregular periods needs a different panel from a 48-year-old experiencing perimenopausal symptoms.

When to Test

Timing is critical for accurate female hormone testing:

If you're still cycling:

• Days 2–5 (day 1 = first day of full flow) — oestradiol, FSH, LH, SHBG, DHEA-S, thyroid panel
• Day 21 (or 7 days post-ovulation) — progesterone to confirm ovulation
• Any time — cortisol (morning, fasted), vitamin D, B12, ferritin, HbA1c

If cycles are irregular or absent:

• Test on any day, noting the irregularity. Repeat FSH and oestradiol 4–6 weeks later for comparison

If post-menopausal or on HRT:

• Test at any time. On transdermal oestrogen, test oestradiol as a trough level (before applying your next patch or gel)

Practical takeaway: The most common mistake in female hormone testing is wrong timing. A progesterone test on day 5 is meaningless; an oestradiol test mid-cycle looks dramatically different from day 3. Time your tests correctly.

Understanding Your Results

Raw numbers without context are frustrating. Here are the principles for interpreting your hormone results:

Compare to the correct reference range. Ranges differ by cycle phase, age, and menopausal status. A "normal" oestradiol for a post-menopausal woman would be considered low in a cycling woman.

Look for patterns, not isolated values. A single mildly elevated FSH doesn't confirm perimenopause. Two elevated readings weeks apart are more meaningful. A declining progesterone trend over several cycles is more informative than one low reading.

Don't ignore "normal" results if you have symptoms. Laboratory reference ranges represent the statistical middle 95% of the tested population — which includes people with undiagnosed conditions. A TSH of 3.8 mIU/L is "normal" by laboratory standards but may be suboptimal for you.

Practical takeaway: Build a personal health record over time. Your results from this year compared to last year reveal trends that a single snapshot never could. That longitudinal view is the foundation of truly personalised healthcare.

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