Hormone Replacement Therapy

Hormone Replacement Therapy (HRT) or menopausal hormonal therapy (MHT), is a form of therapy composed of hormones normally produced by the ovaries. The aim of HRT is to replace these ovarian hormones that cease to function during the menopause. The drop in these hormones is associated with the symptoms outlined previously.

There are different forms of HRT:

  • Combined HRT in the form of oestrogen and progesterone
  • Oestrogen-only HRT
  • Testosterone
  • Other medications with similar effects such as Tibolone and SERMs

Some of these products are synthetic artificial versions of the hormones naturally produced by the ovary, whereas other products are identical in structure to the hormones naturally produced by the ovary (bioidentical or body-identical).

HRT can be taken via the mouth, via the skin as a patch or gel, and vaginally. The most common form of HRT is combined oestrogen and progesterone HRT because progesterone is necessary to protect the lining of the womb from continuous exposure to oestrogen, which could lead to a build-up of the lining of the womb (endometrium), which could eventually lead to endometrial cancer. Women who have had a previous hysterectomy usually have oestrogen-only HRT as progesterone is no longer necessary.

There are further subcategories of combined HRT based on the duration of progesterone within the regimen. Sequential combined HRT is when oestrogen is taken throughout the month, but progesterone for just 12-14 days of the month. This causes a hormone withdrawal bleed like a period. Sequential regimens are usually taken in the perimenopause or early menopause.

Continuous combined HRT is when both oestrogen and progesterone are taken continuously. This form of HRT is usually reserved for women who have gone through the menopause and are no longer having periods. However, the Levonorgestrel-releasing intrauterine system (e.g. Mirena coil) can also be used as the progesterone component of HRT, which also doubles as a contraceptive in the perimenopause, It gives a low level continuous release of progesterone directly to the womb, usually resulting in a very light period or no period at all.

The last few years has seen the advent of changes in clinical practice when it comes to HRT prescribing taking into consideration the cardiovascular “timing hypothesis”, “window of opportunity”, the role of transdermal oestrogen (oestrogen via the skin) as well as body-identical hormones.

The “timing hypothesis” and “window of opportunity” relate to the theory that if HRT is started within 10 years of the menopause or before the age of 60, the advantages generally outweigh the risks, particularly in terms of benefit to the heart, as well as bone protection and cognition (the latter only for women who are symptomatic in this regard, for example are experiencing brain fog, forgetfulness and poor concentration which started around the menopause. It is not a treatment for dementia). Studies have shown that when HRT is started at a time interval of more than 10 years following a woman’s last menstrual period or over the age of 60, the same cardiovascular (heart) benefit doesn’t apply, although it still may improve symptom control.

Also, studies have shown that transdermal oestrogen (oestrogen HRT via the skin)does not increase the risk of a venous thrombo-embolic event (VTE) or a stroke.VTE is a clot in a vein, commonly the leg or the lung.Therefore, it has a lower risk of blood clots and strokes than oral HRT.

There is no definite time-limit on the duration of HRT treatment. It is entirely an individual decision which will depend on symptoms, personal choice and an understanding of the risks and benefits.

Benefits of HRT:

  • Improves symptoms of the menopause
  • Improves bone mineral density
  • Improves “brain fog”, concentration and forgetfulness if symptoms started around the time of the menopause
  • Lowers the risk of cardiovascular disease if started either within 10 years of the menopause or under the age of 60 years
  • Some observational studies show a reduced risk of colorectal cancer with combined regimens

Disadvantages of HRT:

  • Spotting, irregular or heavy vaginal bleeding with different regimens. This usually settles with time or a change of regimen.
  • Small increased risk of venous thrombo-embolic events (blood clots and strokes) with oral products
  • Small increased risk of breast cancer with combined HRT which reduces on stopping (5 extra cases per 1000 users after 7.5 years
    exposure. NICE Guidelines 2015; 2 extra cases per 100 women Lancet 2019)
  • Very small increased risk of ovarian cancer of 1 extra case per 1000 users after 5 years exposure
  • Individual hormonal side-effects such as tender breasts, nausea and headaches with oestrogen, mood changes and bloating with progesterone, and localised hair growth with testosterone. These tend to improve with time and changes to the HRT regimen.

Contraindications to HRT

  • Pregnancy
  • Recent heart attack or poorly controlled angina
  • Recent VTE event (for example, stroke, blood clot or clot in the lung)
  • Suspected or active breast cancer or endometrial cancer
  • Severe or active liver disease
  • Irregular non-investigated vaginal bleeding