HORMONE REPLACEMENT THERAPY

HRT, explained through evidence.

Estrogen, testosterone and progesterone: clinical roles, delivery methods and the studies behind the discussion.

Estrogen (oestrogen)Testosterone Progesterone

Read the exact regimen. Molecule, route, population and clinical indication matter. Foundational studies are included regardless of age. The badge describes historical importance, not certainty or universal applicability. Initial scope: menopausal HRT and male hypogonadism; gender-affirming care, fertility treatment and cancer treatment require their own evidence reviews.

HRT / Estrogen (oestrogen)

Estrogen (oestrogen)

Estrogen is a family of hormones; estradiol and conjugated equine estrogens are different preparations. Research on menopausal HRT includes symptom relief, bone outcomes and longer-term risks. Interpretation depends on the formulation, route, age and population studied. Combined-hormone trial ↗ · Estrogen-alone trial ↗

Women: menopausal HRT

REPLENISH studied an oral estradiol–progesterone capsule for vasomotor symptoms and endometrial safety. WHI studied different oral preparations and major health outcomes. These answer different questions; neither should be described as a trial of every modern HRT regimen. Source ↗ · Source ↗

Men: physiology is not a replacement indication

An experimental study in men separated androgen and estrogen effects on body composition and sexual function. It is relevant background, but does not establish routine estrogen prescribing for male hypogonadism. Source ↗

Delivery methods & technical distinctions

Formulation / route	What the evidence tells us
Oral tablets	WHI used oral conjugated equine estrogen; REPLENISH used oral estradiol with progesterone. Identify the molecule and companion hormone, rather than grouping these as one treatment. Source ↗ · Source ↗
Skin patch / gel	Transdermal estradiol avoids hepatic first-pass metabolism. In ESTHER, oral estrogen—but not transdermal estrogen—was associated with increased venous clot risk. ESTHER was observational: this is not proof that patches are risk-free. Australian product information ↗ · Source ↗
Vaginal cream / ring	Local vaginal treatment has been studied for recurrent urinary infections in postmenopausal women. Vaginal cream can still produce systemic absorption; product and exposure matter. It should not be treated as equivalent to skin gel. Source ↗ · US product label ↗
Injections	No head-to-head menopausal injection-versus-patch trial has been verified for this initial library. Comparative claims are withheld pending product-specific research.

Research library

Recent research plus older foundations · Trials, observational studies and product labels are separately identified · Phases shown only when verified

2024

Secondary analysis of randomized studies

Low-dose and ultra-low-dose estradiol and dydrogesterone in postmenopause: analysis by body mass index ↗

Newer analysis of oral estrogen plus a synthetic progestogen; not progesterone and not an independent new trial.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2023

Observational · corrected article

Menopausal hormone therapy and dementia: nationwide nested case-control study ↗

Reports an association, not causation. Use the corrected record; confounding and treatment-selection effects remain important.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2018

Phase 3 · randomized trial

REPLENISH: oral estradiol–progesterone capsule for vasomotor symptoms ↗

Why it matters: Pivotal evaluation of this combined oral formulation.

Product-specific symptom and endometrial-safety evidence.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2015

Randomized trial ancillary study

KEEPS: cognition and mood in recently postmenopausal women ↗

Why it matters: Tests cognitive outcomes with oral and transdermal regimens closer to menopause.

No cognitive benefit was identified; this is not a dementia-prevention trial.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2007

Case-control study

ESTHER: estrogen route, progestogens and venous thromboembolism ↗

Why it matters: Influential route-specific clot-risk research; foundational does not mean randomized.

Associations can be affected by confounding.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2004

Randomized trial

WHI: estrogen alone after hysterectomy ↗

Why it matters: Major outcomes trial of oral conjugated equine estrogen in women without a uterus.

Higher stroke risk and fewer hip fractures; not evidence for universal disease prevention.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2002

Randomized trial

WHI: estrogen plus progestin ↗

Why it matters: Landmark benefit–risk study that changed menopausal hormone prescribing.

Studied conjugated equine estrogen plus medroxyprogesterone acetate; not micronized progesterone.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2013

Experimental randomized study

Gonadal steroids, body composition, strength and sexual function in men ↗

Why it matters: Helps distinguish androgen and estrogen contributions in men.

Suppression and replacement experiment; not long-term routine HRT.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2021

Randomized trial

Vaginal estrogen for recurrent urinary tract infection ↗

35 women; recruitment and dropout limitations. Older than the rolling five-year window by October 2026.

Abstract / record screened; full-text, conflicts and current correction checks pending.

HRT / Testosterone

Testosterone

Testosterone replacement in men with confirmed hypogonadism and testosterone therapy for specific sexual-health indications in women are separate clinical contexts. In Australia, registered creams have distinct indications for male hypogonadism and postmenopausal hypoactive sexual desire dysfunction (HSDD). TGA registration record ↗

Men: confirmed hypogonadism

TRAVERSE enrolled symptomatic men with two low fasting testosterone results and existing or high cardiovascular risk. Gel was noninferior to placebo for major cardiovascular events; atrial fibrillation, acute kidney injury and pulmonary embolism occurred more often in the testosterone group. This does not establish safety for bodybuilding doses or all delivery methods. Source ↗

Women: sexual-health indication

APHRODITE tested a transdermal patch for low sexual desire in postmenopausal women not taking estrogen. Results cannot establish broad benefits for energy, strength or longevity. Australia’s AndroFeme cream registration is for postmenopausal HSDD. Source ↗ · Source ↗

Results are outcome-specific

The Testosterone Trials found moderate sexual-function benefit but no significant vitality benefit. The later TRAVERSE fracture substudy did not show fracture prevention and observed more clinical fractures with testosterone. Source ↗ · Source ↗

Delivery methods & technical distinctions

Formulation / route	What the evidence tells us
Skin gel / cream	Topical products deliver testosterone through skin. Labels warn of transfer to other people through contact. A male gel trial and a female patch trial do not validate every compounded cream. US gel label ↗ · Australian creams ↗
Intramuscular injections	The cypionate product label describes an oil-soluble ester with an intramuscular half-life of approximately eight days. That is formulation-specific pharmacokinetic information, not a dosing interval or evidence for a particular schedule. US cypionate label ↗
Gel, injections and pellets compared	A 2015 observational comparison assessed hematocrit, lipids and PSA across formulations. Nonrandom allocation and differing regimens limit causal route comparisons. Source ↗
Why technical details matter	Route, ester, assay timing and the outcome being measured must be specified. A serum concentration, symptom change and clinical event are different endpoints. We do not provide dose conversions or individual treatment schedules.

Research library

Recent research plus older foundations · Trials, observational studies and product labels are separately identified · Phases shown only when verified

2024

Randomized trial substudy · TRAVERSE

Testosterone treatment and fractures in men with hypogonadism ↗

More clinical fractures were observed; bone-density improvement should not be equated with fracture prevention.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2023

Phase 4 · randomized noninferiority trial

TRAVERSE: cardiovascular safety of testosterone replacement ↗

Why it matters: Major cardiovascular outcomes trial; recent and foundational.

5,246 men; transdermal gel, not injections. NCT03518034. AbbVie and other funding.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2016

Randomized placebo-controlled trials

The Testosterone Trials: effects of treatment in older men ↗

Why it matters: Established a structured evidence base for symptomatic older men with low testosterone.

790 men aged 65 or older; sexual function, physical function and vitality outcomes. NCT00799617.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2015

Observational comparative study

Gels, injections and pellets: hormones, erythrocytosis, lipids and PSA ↗

Useful route-specific signal; not a randomized route comparison.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2008

Phase 3 · randomized trial

APHRODITE: testosterone for low libido in postmenopausal women ↗

Why it matters: Pivotal trial in postmenopausal women not receiving estrogen.

Patch study; benefits and safety questions are specific to the studied population and exposure.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2013

Experimental randomized study

Androgen and estrogen effects in men ↗

Mechanistic context, not a routine HRT outcomes trial.

Abstract / record screened; full-text, conflicts and current correction checks pending.

HRT / Progesterone

Progesterone

Progesterone and synthetic progestins belong to the broader progestogen category but are not identical compounds. In menopausal HRT, a central role is protection of the endometrium when systemic estrogen is used in someone with a uterus. The PEPI trial and product-specific prescribing information support this role. Source ↗ · US progesterone label ↗

Women: endometrial protection

PEPI found more endometrial hyperplasia with unopposed estrogen, while the tested estrogen-plus-progestogen regimens protected against these changes. Evidence must remain tied to the preparation and regimen studied. Source ↗

Women: symptoms and sleep research

A 2023 Phase 3 perimenopause trial did not find a statistically significant difference in its primary vasomotor-symptom score. Participants reported improvements in perceived night sweats and sleep. Primary and secondary findings should be distinguished. Source ↗

Men: evidence boundary

This initial screened library has not identified a pivotal trial supporting routine progesterone replacement in men. Menopausal endometrial-protection findings must not be extrapolated to men. This is a search limitation, not proof that no research exists.

Delivery methods & technical distinctions

Formulation / route	What the evidence tells us
Oral micronized progesterone	The oral product label includes endometrial protection with estrogen and warns about dizziness and drowsiness. Micronization and the studied formulation matter. US product label ↗
Skin cream	A small study of sequential progesterone cream alongside transdermal estrogen did not demonstrate the desired endometrial response. Cream should not be assumed equivalent to a studied oral regimen. Source ↗
Vaginal progesterone	Route-specific absorption and endometrial effects require separate evidence. The REPLENISH pharmacokinetic paper below concerns an oral capsule and cannot validate vaginal or skin formulations. Source ↗
Injection	Evidence from fertility-treatment formulations would not establish menopausal HRT benefit. No injection-versus-oral menopausal outcome comparison has been verified for this research overview.

Research library

Recent research plus older foundations · Trials, observational studies and product labels are separately identified · Phases shown only when verified

2023

Phase 3 · randomized placebo-controlled trial

Oral micronized progesterone for perimenopausal night sweats and hot flushes ↗

189 participants. Primary symptom-score difference was not statistically significant; perceived night sweats and sleep improved.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2019

Phase 1 and Phase 3 pharmacokinetic / clinical data

Estradiol and progesterone bioavailability: TX-001HR ↗

Oral formulation-specific data; related to REPLENISH, not independent efficacy confirmation.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2018

Phase 3 · randomized trial

REPLENISH: oral estradiol–progesterone capsule ↗

Why it matters: Pivotal evidence for this fixed oral combination.

Combination product; cannot isolate progesterone’s contribution to all outcomes.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2012

Randomized placebo-controlled trial

Oral micronized progesterone for postmenopausal vasomotor symptoms ↗

Why it matters: Early controlled symptom-efficacy study; different population from the 2023 trial.

133 randomized participants; selected healthy early-postmenopausal population. NCT00152438.

Abstract / record screened; full-text, conflicts and current correction checks pending.

2000

Small clinical study

Sequential progesterone cream: endometrium, bleeding and hormone levels ↗

27 women; route-specific evidence boundary, not a verdict on all possible formulations.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY1996

Randomized trial

PEPI: endometrial histology with estrogen and progestogens ↗

Why it matters: Established the importance of endometrial protection with unopposed estrogen.

596 women in the endometrial study; tested cyclic micronized progesterone and synthetic progestin regimens.

Abstract / record screened; full-text, conflicts and current correction checks pending.

FOUNDATIONAL STUDY2002

Randomized trial

WHI: conjugated estrogen plus medroxyprogesterone acetate ↗

Why it matters: Landmark combination-therapy risks; must not be mislabelled as a trial of progesterone.

MPA is a synthetic progestin, not micronized progesterone.

Abstract / record screened; full-text, conflicts and current correction checks pending.

Last screened: 30 October 2026. This is an initial, non-exhaustive editorial library. Product labels are jurisdiction-specific; registration records are not a substitute for checking current Australian product information. No individualized treatment, dose conversion or self-administration protocol is provided.