HRT for Women
What You Actually Need to Know

HRT (Hormone Replacement Therapy) and MHT (Menopausal Hormone Therapy) refer to the same thing. MHT is the preferred modern term — "replacement" implied topping up hormones to youthful levels, which is not the goal. The goal is to maintain sufficient circulating hormone to protect target tissues: brain, bone, heart, vasculature, and urogenital tract.

• Estrogen — the primary hormone of MHT. Responsible for most of the systemic benefits: vasomotor symptom control, bone protection, cardiovascular benefit, neuroprotection. Used alone only in women who have had a hysterectomy.
• Progesterone / Progestogen — required in women with an intact uterus to protect the uterine lining (endometrium) from estrogen-driven overgrowth. The type used matters enormously. Micronised progesterone (body-identical) is not the same as synthetic progestins.
• Testosterone — not included in standard MHT but frequently needed. Women have testosterone receptors throughout the body. Loss of testosterone at menopause affects libido, energy, muscle mass, and cognition.

The Women's Health Initiative (2002) was a large US trial testing oral conjugated equine estrogen + medroxyprogesterone acetate (a synthetic progestin) in women with an average age of 63 years. Most participants were overweight, had cardiovascular risk factors, and were well past menopause. The study was not testing body-identical hormones, not testing transdermal delivery, and not studying perimenopausal women.

The trial was stopped early due to a reported increase in breast cancer. The headlines that followed caused an immediate collapse in HRT prescribing worldwide. What was not widely reported: the absolute risk increase was 8 extra cases of breast cancer per 10,000 women per year. This is comparable to the risk associated with drinking two glasses of wine per night, being overweight, or being sedentary.

The estrogen-only arm of the same trial — women without a uterus who received estrogen alone — showed a decrease in breast cancer incidence. This finding received almost no media coverage.

• Wrong hormones: The trial used oral conjugated equine estrogen and medroxyprogesterone acetate — not body-identical estradiol and micronised progesterone
• Wrong route: Oral estrogen undergoes first-pass liver metabolism, increasing clotting factors. Transdermal estrogen does not.
• Wrong age: Average participant age was 63 — the equivalent of starting hormones 10+ years after menopause. This is not who we are prescribing to.
• Wrong question: The trial was designed to ask whether HRT could prevent cardiovascular disease as a primary therapy — not whether it was safe and beneficial for symptomatic perimenopausal women.

Relative risk is how much a risk changes proportionally. Absolute risk is the actual number of additional cases. A headline saying "HRT doubles breast cancer risk" sounds catastrophic. If the baseline risk is 1 in 1,000, "double" means 2 in 1,000 — one extra case. Headlines use relative risk. You should think in absolute risk.

The largest analysis of breast cancer risk and HRT (Collaborative Group, Lancet 2019, >100,000 women) found that combined estrogen-progestogen HRT was associated with increased breast cancer risk that persisted after stopping. However, this analysis also predominantly used older synthetic progestogens — not micronised progesterone — and did not stratify sufficiently by delivery route.

• Estrogen alone (in women without a uterus): the WHI estrogen-only arm showed a reduction in breast cancer with oral CEE. Transdermal estradiol data is also reassuring.
• Micronised progesterone (Utrogestan): the E3N cohort study (France, 80,000 women) showed no increased breast cancer risk with transdermal estradiol + micronised progesterone even after 8 years of use. The risk signal appeared only with synthetic progestins.
• Synthetic progestins (MPA): these appear to be the primary driver of breast cancer risk in combined HRT. They have different receptor binding profiles and oppose estrogen's beneficial effects on breast tissue differently than natural progesterone.

For a woman in her early 50s using transdermal estradiol with micronised progesterone, the current best evidence suggests the breast cancer risk is at most comparable to — and possibly lower than — the risk associated with obesity, alcohol consumption (even moderate), or being sedentary. These lifestyle factors are not met with the same prescriber caution as HRT.

Estrogen is the primary regulator of bone remodelling in women. After menopause, bone resorption accelerates markedly — women lose 2–3% of bone density per year in the first 5 years post-menopause. MHT is the most effective intervention for preventing this loss. It reduces fracture risk by approximately 25–30%. This is not a secondary effect — bone protection is one of the clearest, most consistent benefits in the literature.

Estrogen maintains endothelial function, reduces LDL cholesterol, increases HDL, reduces arterial stiffness, and has direct anti-inflammatory effects on the vascular wall. Women who start MHT within 10 years of menopause (the "timing hypothesis") show 30–50% reduction in cardiovascular events in observational data. The window of benefit closes when atherosclerosis is already established — which is why starting late (as in the WHI) shows no cardiovascular benefit.

Estrogen is anabolic for muscle — it activates satellite cells and supports protein synthesis. Post-menopausal women lose muscle mass faster than men of the same age, partly due to estrogen loss. MHT preserves muscle mass, improves insulin sensitivity, reduces visceral fat accumulation, and reduces the risk of developing type 2 diabetes by approximately 30% in meta-analyses.

Genitourinary Syndrome of Menopause (GSM) — vaginal dryness, urinary urgency, recurrent UTIs, painful intercourse — affects up to 50% of postmenopausal women and, unlike hot flushes, does not resolve without treatment. Systemic estrogen helps. Local vaginal estrogen (cream, pessary, ring) helps more — and carries no systemic risk. It is the most under-prescribed tool in menopausal medicine.

Estrogen stimulates collagen production, maintains skin thickness and elasticity, and reduces the rate of skin ageing. Collagen loss in the first years post-menopause is rapid — up to 30% in 5 years. MHT significantly slows this. Hair thinning driven by the androgen-estrogen ratio shift also responds partially to MHT, particularly when combined with testosterone.

Oral estrogen passes through the liver before reaching circulation (first-pass hepatic metabolism). This increases the production of clotting factors (factor VII, fibrinogen), C-reactive protein, and sex hormone binding globulin — raising VTE (blood clot) risk by approximately 2–4 fold compared to no HRT.

Transdermal estrogen (patch, gel, spray) is absorbed directly into the bloodstream, bypassing the liver. It does not increase clotting factors. VTE risk with transdermal estradiol is not significantly elevated above baseline in women without thrombophilia. This is not a minor distinction — for women with migraine, obesity, or thrombophilia history, it is clinically essential.

• Patches (e.g. Estradot, Climara): Changed every 3–4 days or weekly depending on brand. Consistent delivery. Skin irritation in some women. Avoid thighs if using testosterone gel in same site.
• Gel (e.g. Oestrogel, Sandrena): Applied daily to inner arm or thigh. Dose is easily adjustable — useful during perimenopause when requirements fluctuate. Most flexible option.
• Spray (e.g. Lenzetto): Applied to inner forearm. Convenient, dries quickly. Fixed dose per spray.

Oral estradiol (not conjugated equine estrogen) remains an option for women without VTE risk factors or migraine, who have difficulty with transdermal adhesion or skin sensitivity. It should not be the default first choice for most women — but it is not categorically wrong if there is no thrombophilia history and cardiovascular risk is low.

Estrogen alone stimulates the uterine lining to grow. Without progesterone to balance this, the endometrium can undergo hyperplasia and, over time, progress to endometrial cancer. Any woman with an intact uterus who takes estrogen must take a progestogen to protect the endometrium. Women who have had a hysterectomy can take estrogen alone.

Micronised progesterone is structurally identical to the progesterone your body produces. It binds to progesterone receptors without the additional receptor interactions that synthetic progestins have. Key advantages:

• No increase in breast cancer risk in the E3N cohort (vs clear increase with synthetic progestins)
• Does not oppose estrogen's cardiovascular benefits (unlike MPA)
• Has a mild calming, sleep-promoting effect (via GABA receptor interaction) — often beneficial in perimenopause
• Does not worsen mood, libido, or metabolic markers in the way synthetic progestins can

Medroxyprogesterone acetate (MPA), norethisterone, levonorgestrel, and others are synthetic progestogens. They bind to progesterone receptors but also to androgen, glucocorticoid, and mineralocorticoid receptors — producing effects that natural progesterone does not. MPA in particular is associated with increased breast cancer risk, adverse lipid effects, and worsening of mood and libido. It was the progestogen used in the WHI.

Testosterone is not a male hormone. It is produced in the ovaries and adrenal glands throughout a woman's life — and at its peak (in the 20s), women have more circulating testosterone than estrogen. From the mid-30s onwards, testosterone declines steadily. Surgical menopause causes an immediate 50% drop. Most women are never told this, and most doctors never test for it.

• Libido and sexual function: the clearest, best-evidenced benefit. The Global Consensus Position Statement (2019) supports testosterone for hypoactive sexual desire disorder in postmenopausal women — the strongest recommendation in the testosterone-for-women literature.
• Muscle mass and strength: testosterone is directly anabolic. Women with low testosterone lose muscle faster. Testosterone replacement supports lean mass and resistance training response.
• Energy and motivation: testosterone drives dopaminergic reward circuitry. Low testosterone presents as fatigue, flat affect, lack of drive — symptoms frequently misattributed to depression.
• Cognition: testosterone receptors are expressed throughout the brain. Early data suggest benefit for working memory and processing speed. Research is ongoing.
• Bone: testosterone contributes to bone mineral density independently of estrogen.

There are no female-approved testosterone products in most countries — doses are extrapolated from male formulations. Androfeme 1% cream is available in Australia and is the only female-licensed testosterone product in the world. Male testosterone gels (AndroGel, Testogel) are used off-label at 1/10th of the male dose. The target is to restore testosterone to the upper end of the normal female premenopausal range — not to supraphysiological levels.

The timing hypothesis proposes that the benefits of estrogen — particularly cardiovascular and neurological — depend on starting therapy within 10 years of menopause or before age 60. During this window, estrogen receptors in the vasculature and brain are still responsive and tissues are not yet damaged. Starting after this window (as in the WHI) does not produce the same benefit and may, in women with subclinical atherosclerosis, transiently increase risk.

Perimenopause can begin 8–10 years before the final period. During this time, estrogen fluctuates wildly — sometimes high, sometimes low — producing symptoms including: brain fog, insomnia, anxiety, heart palpitations, irregular periods, joint pain, and worsening PMS. Blood tests are often normal (because FSH is only consistently elevated after menopause). This is the window when many women are told nothing is wrong.

Because estrogen fluctuates in perimenopause rather than simply falling, standard continuous MHT can sometimes worsen symptoms on high-estrogen days. A sequential (cyclical) regimen — matching the fluctuating hormonal environment — is often more appropriate early in perimenopause. This is an area requiring clinical judgment and often more frequent dose adjustment than post-menopausal MHT.

Perimenopause does not mean infertility. Pregnancy is still possible — and unintended pregnancy rates in perimenopausal women are higher than most women expect. Standard MHT does not provide contraception. Options include: the Mirena IUD (provides endometrial protection AND contraception), low-dose combined oral contraceptive pill (also manages perimenopausal symptoms), or barrier methods alongside MHT.

Estrogen receptors (ERα and ERβ) are expressed throughout the brain — in the hippocampus, prefrontal cortex, amygdala, and cerebellum. Estrogen promotes synaptic plasticity, supports cerebral blood flow, reduces neuroinflammation, and facilitates glucose metabolism in neurons. It also regulates serotonin, dopamine, and acetylcholine — neurotransmitters central to mood, memory, and executive function.

Word-finding difficulty, working memory lapses, difficulty concentrating, and processing slowdown are among the most distressing symptoms of perimenopause — and among the most frequently dismissed. They are biologically real: neuroimaging studies show measurable changes in hippocampal activation and default mode network connectivity during the menopausal transition. These changes are partially reversible with estrogen therapy.

Women account for approximately two-thirds of all Alzheimer's cases. This is not explained by longevity alone. Estrogen loss at menopause appears to accelerate amyloid and tau pathology. The WHIMS sub-study of the WHI (using oral CEE with MPA in elderly women) showed increased dementia risk — but this finding has been attributed to the late-start problem (starting in women with existing subclinical pathology) and the wrong formulation. Observational data consistently show that women who start MHT within 5 years of menopause have lower dementia and Alzheimer's risk.

The current evidence does not support prescribing MHT specifically for dementia prevention as a sole indication. However, for a symptomatic perimenopausal woman with family history of Alzheimer's who is starting MHT for symptom relief, the emerging neuroprotective data is a meaningful additional benefit — not a risk.

After the WHI, many guidelines advised women to take HRT for the shortest time at the lowest dose. The 5-year figure was not derived from a clinical trial comparing 5 vs 10 years — it was a precautionary statement born from uncertainty. It has since been repeated so often it is treated as a law. It is not.

• British Menopause Society (2020): "There is no arbitrary time limit on the duration of MHT use." Women should make individualised decisions based on ongoing symptom burden and risk-benefit review.
• The Menopause Society (formerly NAMS, 2022): Supports extended use for appropriate women, particularly for ongoing bone and cardiovascular protection.
• NICE Guidelines (UK, 2019 updated 2023): Women should not be routinely restricted to 5 years. Annual review is appropriate.

When estrogen is stopped, bone loss accelerates again, cardiovascular risk factors re-emerge, and urogenital symptoms return — often within months. The notion that you "need to come off" HRT periodically to "give your body a rest" has no biological basis. If the indication for starting MHT was valid, and the woman's health is being monitored, continuing indefinitely is a legitimate clinical choice.

• Current symptom control — is the dose still appropriate?
• Blood pressure, weight, cardiovascular risk factors
• Breast screening is up to date
• Bone density (DEXA) every 2–3 years if any osteopenia risk
• New personal or family history of breast cancer, thrombosis, or cardiovascular disease
• Quality of life — is MHT still contributing meaningfully?

• Current or recent breast cancer (oestrogen-receptor positive) — avoid systemic estrogen. Local vaginal estrogen may be considered with oncologist input in specific cases.
• Unexplained vaginal bleeding — investigate before starting MHT
• Active or recent VTE (DVT/PE) — oral estrogen is contraindicated; transdermal estradiol with haematology input may be considered after the acute event has resolved
• Active liver disease — oral estrogen contraindicated; transdermal may be possible
• Known or suspected estrogen-dependent tumours other than breast cancer (some uterine tumours)

• Migraine with aura: oral estrogen increases stroke risk; transdermal estradiol is considered safe — avoiding the oral route resolves the concern
• Thrombophilia (e.g. Factor V Leiden): transdermal estradiol does not increase VTE risk; haematology co-management recommended
• Controlled hypertension: not a contraindication; blood pressure monitoring appropriate
• Obesity: oral estrogen increases VTE risk further; transdermal preferred — not a contraindication to MHT, but a reason to use the right delivery route
• BRCA1/2 carriers who have had prophylactic bilateral salpingo-oophorectomy: MHT is strongly recommended at least until the natural age of menopause — surgical menopause at 35–40 carries significant long-term harm

• FSH, LH, estradiol — to confirm menopausal/perimenopausal status (though in perimenopause, normal values don't rule it out)
• Total and free testosterone, SHBG — baseline before testosterone therapy
• Thyroid function (TSH) — thyroid disorders mimic perimenopause and are common
• Lipid panel, fasting glucose, HbA1c — cardiovascular and metabolic baseline
• Blood pressure
• Mammogram — up to date before starting
• DEXA scan — if osteopenia risk or age >50

• Estradiol levels: not routinely needed for symptom control (titrate by symptoms), but useful if symptoms persist or to avoid supraphysiological levels. Serum estradiol on transdermal therapy should ideally be 200–400 pmol/L for symptom relief without excess.
• Testosterone (free and total): check 4–6 weeks after starting testosterone. Target: upper end of normal female premenopausal range. Do not exceed.
• Endometrial monitoring: if unexpected bleeding on continuous combined MHT beyond 6 months, investigate with ultrasound ± hysteroscopy.

The DUTCH (Dried Urine Test for Comprehensive Hormones) measures estrogen metabolites, progesterone metabolites, testosterone metabolites, cortisol, DHEA-S, and melatonin markers. It provides a more complete picture of hormone metabolism than serum tests — particularly useful for understanding how a woman is metabolising her estrogen (the 2-OH vs 16-OH estrogen metabolite ratio has cancer-risk implications) and for tailoring MHT. It is a supplement to serum testing, not a replacement.

The standard of menopause care varies enormously. Ask prospective doctors: Do you prescribe body-identical hormones? Do you use transdermal estrogen as a first choice? Do you prescribe testosterone for women? Do you have a view on the 5-year limit? The answers to these four questions will tell you quickly whether you are talking to a clinician current with the evidence.