Hormone Replacement Therapy (HRT) Combined or Oestrogen Only?

HRT administered orally as a tablet or through the skin as a patch, gel, or spray is referred to as systemic therapy, meaning it circulates throughout the entire body. When both oestrogen and a progestogen are taken, it is termed combined HRT, whereas if only oestrogen is used, it is known as oestrogen-only HRT.

When oestrogen is exclusively applied within the vagina using a tablet, cream, pessary, gel, or ring, this is categorised as localised treatment because its effects are primarily observed in the vaginal and bladder areas, with minimal hormonal dispersion throughout the body.

Combined HRT

To alleviate symptoms resulting from low or fluctuating oestrogen levels, women typically require oestrogen replacement. If a woman still has a womb (uterus), she will also need a progestogen to protect the uterine lining. This is known as combined HRT, which can be administered in one of two ways:

If a woman has experienced a period within the last 6-12 months, sequential HRT is usually recommended. This regimen involves taking oestrogen daily and a progestogen for 12-14 days out of every 28. For simplicity, women are often advised to follow a pattern of 2 weeks on and 2 weeks off, which typically results in a monthly menstrual bleed. If a monthly bleed is undesired, the use of a Mirena coil can be considered. Once settled, most women experience minimal or no bleeding with the Mirena coil. It can be especially beneficial during the perimenopause when periods can be heavy, and contraception is still needed. The Mirena coil can be used as part of HRT for up to 5 years before requiring replacement.

If a woman has not had a period for 12 months or more, starting continuous combined HRT is usually recommended. This involves taking both oestrogen and a progestogen daily. Some vaginal bleeding is common when initiating this combination, but it typically resolves within 3-6 months, after which no further bleeding is anticipated.

Oestrogen-only HRT

Women who have undergone a hysterectomy (removal of the womb) typically take oestrogen-only HRT on a daily basis. The absence of the womb eliminates the need for a progestogen to protect the uterine lining (endometrium).

However, there are some exceptions to this rule:

Women who have had a hysterectomy as part of their endometriosis treatment may still have residual endometrial patches in the pelvis that were difficult to remove safely. In such cases, their gynaecologist may recommend a daily progestogen as part of their HRT to prevent stimulation of the remaining endometrial patches. Women with a history of endometriosis are typically prescribed a daily progestogen.

Some women, during a hysterectomy, opt to retain the cervix rather than having the entire womb removed. In these cases, a portion of the uterine lining (endometrium) may remain. If this is the situation, combined HRT with both oestrogen and a progestogen is necessary to prevent thickening of the remaining endometrium.

This procedure involves destroying the lining of the womb and is used to reduce menstrual blood loss in women with heavy periods. In some women, it leads to the cessation of periods altogether. However, the uterine lining is not entirely eliminated. Women who have undergone endometrial ablation require combined HRT.

Localised Vaginal Oestrogen

Women experiencing symptoms such as vaginal dryness, soreness, itching, pain during intercourse, increased urinary frequency, recurrent urinary tract infections, or nocturia (getting up at night to urinate) can benefit from using vaginal oestrogen. These symptoms result from a lack of oestrogen in the tissues of the bladder, vagina, vulva, and pelvic floor, collectively referred to as Genitourinary Syndrome of Menopause. By applying oestrogen locally within the vagina via a tablet, gel, pessary, cream, or ring, these symptoms can be alleviated. Since only a minute amount of oestrogen is absorbed into the body, progestogen supplementation is unnecessary.

Localised vaginal oestrogen can safely be used in combination with systemic HRT if required for symptom management.