microbiome signatures definitions

Hormone Replacement Therapy (HRT)

August 20, 2025

Hormone Replacement Therapy (RT), also widely known as Menopausal Hormone Therapy (HT), refers to the medical use of hormones, primarily estrogen, with or without a progestogen, to replace the natural decline in ovarian hormone production that occurs during the menopausal transition.[1] The therapy is intended to alleviate the diverse symptoms caused by falling estrogen levels […]

Last Updated: 2025-08-20

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Divine Aleru

I am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.

Overview

Hormone Replacement Therapy (HRT), also widely known as Menopausal Hormone Therapy (MHT), refers to the medical use of hormones, primarily estrogen, with or without a progestogen, to replace the natural decline in ovarian hormone production that occurs during the menopausal transition.[1] The therapy is intended to alleviate the diverse symptoms caused by falling estrogen levels and, in certain cases, to provide long-term protective benefits for bones and overall health.[2] Estrogen is the principal hormone used, while progesterone or synthetic progestins are added in women with an intact uterus to prevent endometrial overgrowth and reduce the risk of endometrial cancer.[3][4] For women who have undergone a hysterectomy, estrogen alone may be sufficient.[5]

The main reason HRT is prescribed is to relieve vasomotor symptoms such as hot flashes and night sweats, which are the most common and distressing complaints during menopause.[6] Beyond vasomotor relief, HRT improves sleep, mood, and sexual function by addressing symptoms of genitourinary syndrome of menopause (GSM), including vaginal dryness, painful intercourse, and urinary frequency. In addition, systemic estrogen therapy helps to maintain bone density and reduce fracture risk, making it especially important for women who enter menopause early or who are at high risk for osteoporosis. For many women, these benefits contribute to significant improvements in quality of life, work productivity, and psychosocial well-being.

Benefits of Hormone Replacement Therapy

The primary goal of HRT is to relieve symptoms caused by declining estrogen levels during menopause. Decades of clinical trials and observational studies have shown that HRT is the most effective treatment for vasomotor symptoms such as hot flashes and night sweats, while also offering additional advantages for bone health, vaginal and urinary function, and quality of life. These benefits are most significant for women who begin therapy soon after menopause, particularly those experiencing premature or early menopause.

BenefitWhat It DoesEvidence & Clinical Significance
Relief of Vasomotor SymptomsReduces hot flashes and night sweats by up to 70–80% in most women.RCTs and meta-analyses confirm HRT is the most effective treatment for vasomotor symptoms, often working within weeks. Improves comfort, work performance, and daily activities.
Improved Sleep & MoodBetter sleep quality by reducing night sweats; may help with mood swings, anxiety, and “brain fog.”Women often report fewer awakenings, improved concentration, and enhanced emotional stability. Indirect benefits on cognition through sleep improvement are recognized.
Vaginal & Urinary Health (GSM)Restores vaginal tissue thickness, elasticity, and lubrication; reduces painful intercourse and urinary frequency/urgency.Local vaginal estrogen and systemic estrogen are first-line for GSM. Studies show long-term safety of low-dose vaginal preparations, with minimal systemic absorption.
Bone Density & Fracture PreventionPrevents postmenopausal bone loss and reduces vertebral, hip, and other fractures while on therapy.WHI and other trials show a ~30–40% reduction in hip and vertebral fractures. Particularly important for women with early menopause or high osteoporosis risk.

References

  1. Hormone Replacement Therapy. [Updated 2024 Oct 6].. Harper-Harrison G, Carlson K, Shanahan MM.. (In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.)
  2. Optimizing menopausal hormone therapy: For treatment and prevention, menstrual regulation, and reduction of possible risks.. Ruan, X., & Mueck, A. O. (2022).. (Global Health Journal, 6(2), 61-69.)
  3. Adverse endometrial effects during long cycle hormone replacement therapy.. Bjarnason, K., Cerin, Å., Lindgren, R., & Weber, T. (1999).. (Maturitas, 32(3), 161-170.)
  4. Progesterone: The ultimate endometrial tumor suppressor.. Yang, S., Thiel, K. W., & Leslie, K. K. (2011).. (Trends in Endocrinology and Metabolism: TEM, 22(4), 145.)
  5. Estrogen Therapy. [Updated 2025 Feb 18].. Valdes A, Patel P, Bajaj T.. (In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.)
  6. Hormone Replacement Therapy. [Updated 2024 Oct 6].. Harper-Harrison G, Carlson K, Shanahan MM.. (In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.)

Harper-Harrison G, Carlson K, Shanahan MM.

Hormone Replacement Therapy. [Updated 2024 Oct 6].

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.

Bjarnason, K., Cerin, Å., Lindgren, R., & Weber, T. (1999).

Adverse endometrial effects during long cycle hormone replacement therapy.

Maturitas, 32(3), 161-170.

Yang, S., Thiel, K. W., & Leslie, K. K. (2011).

Progesterone: The ultimate endometrial tumor suppressor.

Trends in Endocrinology and Metabolism: TEM, 22(4), 145.

Read Review

Valdes A, Patel P, Bajaj T.

Estrogen Therapy. [Updated 2025 Feb 18].

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.

Harper-Harrison G, Carlson K, Shanahan MM.

Hormone Replacement Therapy. [Updated 2024 Oct 6].

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.

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