Hormone Replacement Therapy

Article Author:
Gina Harper-Harrison
Article Editor:
Meaghan Shanahan
Updated:
5/30/2019 9:04:48 PM
PubMed Link:
Hormone Replacement Therapy

Indications

Hormone replacement therapy (HRT) is supplementing women with hormones that are lost during the menopausal transition. To relieve the symptoms associated with menopause, conventional HRT includes an estrogen and progesterone component to mimic hormones created by the human ovary.

Estrogen therapies are numerous, and include those indigenous to the human ovary, for example, estradiol and estriol. Other estrogenic compounds include conjugated equine estrogen (CEE), the most commonly prescribed estrogen in the United States. They are not identical in their effect on the human body but share the same FDA indications according to the Physicians Desk Reference. [1][2][3]The indications for menopausal issues include:

  • Treatment of vasomotor symptoms of menopause
  • Treatment of genitourinary syndrome of menopause ( previously known as vaginal and vulvar atrophy)
  • Prevention of osteoporosis

Progestogen is a term used to include not only progesterone made by the human ovary but also progesterone-like substances, also known as progestins. A woman who desires HRT and has an intact uterus must have a progestogen with estrogen to protect her uterus from endometrial hyperplasia or malignancy. Estrogen alone will cause the endometrial lining to grow. Progestogens stabilize the lining from proliferating abnormally. It is assumed that if a woman has had a hysterectomy that she no longer needs a progestin. Progesterone, however, is different as it can provide symptom relief from sleep disturbance and mood instability and increasing evidence support that it offers tissue protection to the breast.[4][5][6]

FDA-approved indications for progestogens include:

  •  Amenorrhea, either primary or secondary
  •  Assisted reproductive technology treatment
  •  Endometrial hyperplasia
  •  Dysfunctional uterine bleeding

Administration

There are numerous estrogen and progestogen choices, and they may be administrated orally or transdermally either through cream, patch, vaginal inserts, or subdermal pellets. Each route of administration has unique benefits and risks.

Oral Estrogen: Any estrogen administered orally results in increased activated protein-C resistance, increasing the risk of a blood clot. Oral estradiol also induces the hepatic formation of matrix metalloprotease 9, which decreases the formation and rupture of atherosclerotic plaque.

Transdermal Estrogen: Bypasses the hepatic metabolism that produces activated protein-C resistance, and the risk for blood clotting is negated.

Progestins are usually administered orally, although a few are available in combination with estrogen in patch forms. Progesterone is available in an oral form that can also be used vaginally for non-FDA-approved uses.

Specialized pharmacies make compounded estrogen and progesterone creams, sublingual troches, and vaginal inserts, but these are not FDA approved and are not be included in this article.

Adverse Effects

When studying the potential adverse effects of HRT, the most referenced information in the United States comes from the Women's Health Initiative (WHI).[7][8][9]

WHI Trial

This was a multifaceted trial, including 2 double-blind, placebo-controlled, randomized trials of postmenopausal hormone therapy.

The first arm included CEE at 0.625 mg per day with medroxyprogesterone acetate (MPA) 2.5 mg per day. The second arm was comprised of patients who had prior hysterectomies and treated with CEE 0.625 mg only.

HRT and the Breast

The CEE/MPA arm was discontinued earlier than expected due to an increased incidence of invasive breast cancer of 24% (HR=1.24). The CEE only arm was not discontinued early, completed in 2004, and extended follow up of patients has continued for 11.8 years. CEE use for 5 to 9 years is associated with a statistically significant reduction in breast cancer by 23% (HR=0.77). Those in the CEE arm also had decreased mortality from breast cancer by 63% compared to those not on CEE, and 38% fewer died from all other causes after breast cancer was diagnosed.

When examining evidence from European studies which usually use estradiol derivatives rather than CEE, and non-MPA progesterone or progestins, the conclusions are vastly different and unequal. Transdermal estradiol alone increased the risk of breast cancer by 10%, but with progesterone decreased the risk of breast cancer by 10%.

HRT and the Heart

In the WHI CEE/MPA arm, the overall incidence of coronary heart disease (CHD) increased by 24% over 5 years of use, with the most substantial elevation in risk within the first year, with an increase of 81% (HR=1.81). This evidence needs to be interpreted with caution due to the following:

  • The average age of the patient treated in this study was 62 years. In women who were started on therapy within 10 years of menopause, the risk of CAD was reduced by 11% (HR=0.89), but this was not found to be statistically significant.
  • In those women who continued CEE/MPA for over 6 years, the risk of CAD was lowered by 30% (HR=0.70).

These risks do not apply to estradiol and progesterone based treatments. Basic science studies show several mechanisms through which estradiol (not CEE) is cardioprotective. These include stabilization of atherosclerotic plaques, reduction of carotid intima-media thickness (CIMT), and decreasing coronary artery calcium (CAC) scores. Numerous subsequent studies both in Europe and the United States show that cardiovascular disease and death are prominently reduced when HRT is initiated within the first 4 years of the menopause transition. The "Timing Hypothesis" refers to the theory that when HRT is initiated closer to the time of the menopause transition, a cardiovascular benefit is seen compared with later initiation.

HRT and Risk of Stroke

Stroke incidence increased in both arms of the WHI trial by 31% in the CEE/MPA arm, and 39% in the CEE arm.

Studies using oral estradiol are conflicted, showing a similar stroke risk, but the incidence of fatal stroke is unchanged.

HRT and the Risk of Venous Thromboembolism (VTE)

VTE, comprised of deep venous thrombosis and pulmonary embolism, was increased by 2-fold (HR= 2.06) in the WHI CEE/MPA arm.

Transdermal estradiol does not confer the same thromboembolic risk, as is evidenced by numerous European studies. The ESTHER study from France showed an overall risk of 0.9 for a blood clot, which is a decreased risk. Subsequent studies looking at other transdermal estradiol doses and routes confirm these findings, with at least a null effect for blood-clotting risk.

Contraindications

Contraindications for oral or transdermal estrogen-based therapies include:

  • Known, suspected or history of breast cancer
  • Known or suspected history of other estrogen-based cancer, i.e., uterine cancer. Women who have had a hysterectomy and have no remaining evidence of disease are still candidates for HRT
  • Active deep venous thrombosis (DVT) or a history of DVT or pulmonary embolism (PE)
  • History of blood clotting disorder, the most common being Factor V Leiden mutation carriers
  • Active or history of arterial thrombotic diseases such as myocardial infarction or stroke
  • Chronic liver disease or dysfunction

These contraindications do not apply to transvaginal based estrogen therapies, as the serum concentration of estrogen from this route is extremely low. The North American Menopause Society (NAMS) has recommended that the black-box warning that applies to conventional HRT not be applied to transvaginal estrogen treatments.

Monitoring

Hormone levels of estradiol and progesterone are not traditionally done for monitoring purposes. Rather, the relief of menopausal symptoms and the absence of adverse effects signify an adequate medical response.

Adverse side effects may include:

  • Abnormal uterine bleeding
  • Fluid retention
  • Breast tenderness
  • Headaches
  • Mood changes

No scientific evidence links HRT with significant weight gain.

HRT including androgen therapies such as testosterone should be monitored with serum testing but is not considered conventional HRT.

Enhancing Healthcare Team Outcomes

Patients undergoing menopause should be managed by a multidisciplinary team that also includes the pharmacist and nurse. To improve patient outcomes, clinicians should not empirically prescribe hormone replacement therapy. These hormones have been associated with a variety of adverse effects including an increased risk of breast cancer, stroke, heart disease, and deep vein thrombosis. The duration of treatment of these hormones should not be more than a few years and close monitoring is required. If the female has mild symptoms of menopause, then education should be provided about the benefits and harm of these hormones.


References

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[2] Abu Zaid M,Dinh PC,Monahan PO,Fung C,El-Charif O,Feldman DR,Hamilton RJ,Vaughn DJ,Beard CJ,Cook R,Althouse S,Ardeshir-Rouhani-Fard S,Sesso HD,Huddart R,Mushiroda T,Kubo M,Dolan ME,Einhorn LH,Fossa SD,Travis LB, Adverse Health Outcomes in Relationship to Hypogonadism After Chemotherapy: A Multicenter Study of Testicular Cancer Survivors. Journal of the National Comprehensive Cancer Network : JNCCN. 2019 May 1;     [PubMed PMID: 31085753]
[3] Valdes A,Bajaj T, Estrogen Therapy 2019 Jan;     [PubMed PMID: 31082095]
[4] Gliemann L,Hellsten Y, The exercise timing hypothesis - Can exercise training compensate for the reduction in blood vessel function after menopause if timed right? The Journal of physiology. 2019 May 11;     [PubMed PMID: 31077368]
[5] Cho HW,Ouh YT,Lee JK,Hong JH, Effects of hormone therapy on recurrence in endometrial cancer survivors: a nationwide study using the Korean Health Insurance Review and Assessment Service database. Journal of gynecologic oncology. 2019 Jan 25;     [PubMed PMID: 31074237]
[6] Ortac M,Hidir M,Salabas E,Boyuk A,Bese C,Pazir Y,Kadioglu A, Evaluation of gonadotropin-replacement therapy in male patients with hypogonadotropic hypogonadism. Asian journal of andrology. 2019 May 3;     [PubMed PMID: 31062720]
[7] Gordhandas S,Norquist BM,Pennington KP,Yung RL,Laya MB,Swisher EM, Hormone replacement therapy after risk reducing salpingo-oophorectomy in patients with BRCA1 or BRCA2 mutations; a systematic review of risks and benefits. Gynecologic oncology. 2019 Apr;     [PubMed PMID: 30661763]
[8] Vinogradova Y,Coupland C,Hippisley-Cox J, Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ (Clinical research ed.). 2019 Jan 9;     [PubMed PMID: 30626577]
[9] Salagame U,Banks E,O'Connell DL,Egger S,Canfell K, Menopausal Hormone Therapy use and breast cancer risk by receptor subtypes: Results from the New South Wales Cancer Lifestyle and EvaluAtion of Risk (CLEAR) study. PloS one. 2018;     [PubMed PMID: 30403669]