Gynaecology - GnRH Analogues for Pelvic Pain

Why I have I been offered this treatment?

Gonadotrophin-releasing hormone (GnRH) analogue injections are offered to patients with a gynaecological condition that driven by hormones of the menstrual cycle.

Examples of this include:

• Endometriosis, adenomyosis, pelvic pain
• Fibroids
• Heavy Periods
• Severe PMS (pre-menstrual syndrome)

GnRH analogue injections are also occasionally used as a method of diagnosing whether symptoms are gynaecological in nature.

The overall aim of these injections is to improve symptoms by stopping the menstrual cycle.

This treatment can also be used in preparation for surgery (for example to reduce the severity of the condition pre-operatively), or as a medical treatment as an alternative to complex surgery.

The reasons for opting for this treatment will be differ depending on your condition and you will have opportunity to discuss this in detail with your gynaecologist.

What are the different types of injections and how are they given?

The brand names for the most commonly used injections are Prostap and Zoladex. They are both GnRH analogues, come in injection form and work in the same way. Prostap is given into a muscle. Zoladex is administered subcutaneously (into the top layer of fatty tissue directly under the skin) and is in the form of a small capsule, so you may notice a small lump under the injection site.

How does this treatment work?

GnRH analogues are synthetic hormones that affect the release of hormones from the pituitary gland (luteinizing hormone (LH) and follicle stimulating hormone (FSH). LH and FSH stimulate release of oestrogen and progesterone from the ovaries, so as their levels are reduced, so are the production of oestrogen and progesterone.

As a result, the monthly hormonal cycle (and therefore symptoms related to it) is ‘switched off’ in a temporary, medically induced menopause. The injections release hormone slowly, over a period of time so the affects will last for 1 to 3 months, depending on the dose.

It is important to note that when the medication is first administered, there is an initial rise in the circulating hormones so an initial flare-up of symptoms may be noticed.

However, this should only last for the first two weeks of the treatment. Most women will stop having periods and notice an improvement of symptoms within the first two months.

What are the side effects?

The majority of side effects are related to reduced levels of oestrogen and can be similar to symptoms of the menopause. Symptoms can include hot flushes, altered mood and vaginal dryness.

Another important side effect of GnRH analogues is reduction in bone mineral density (osteoporosis). This is also related to reduced levels of oestrogen.

Very common (may affect more than 1 in 10 people)

Difficulty sleeping, headaches or hot flushes.

Common (may affect up to 1 in 10 people)

Weight changes, mood changes, depression, tingling in hands or feet, dizziness, nausea, joint pain, muscle weakness, breast tenderness, changes in breast size, vaginal dryness, swelling in ankles or skin reactions at the injection site (these include skin hardening, redness, pain, abscesses, swelling, nodules, ulcers, and skin damage).

Uncommon (may affect up to 1 in 100 people)

Loss of appetite, changes in blood lipids (cholesterol), altered vision, pounding heartbeats, diarrhoea, vomiting, abnormalities in liver blood tests, hair loss, muscle aches, fever, chills, or tiredness.

Not known (frequency cannot be estimated from the available data)

Blood tests may show anaemia (low red cell counts), low counts in white cells or platelets, allergic reactions (may include symptoms of rash, itching, wheals, or a serious allergic reaction causing difficulty breathing or dizziness), changes in blood sugar, paralysis, blood clots in the lungs, high or low blood pressure, jaundice, abnormalities in liver function, fracture of the spine, seizure, thinning of bone, vaginal bleeding, inflammation of lungs or lung disease.

How can these side effects be managed?

Hormone Replacement Therapy (HRT) can be used to reduce symptoms of low oestrogen.

This is usually given as a low dose oestrogen preparation (e.g., Tibolone) and the dose is low enough so not to reduce the effectiveness of the treatment in managing the gynaecological condition. This is known as add-back HRT, and it’s use also reduces the risk of associated osteoporosis (bone-thinning).

GnRH analogues are only licensed for up to 6 months’ treatment at a time. However, if after discussion of risks and benefits, you and your gynaecologist decide that a longer course of treatment would be appropriate for your condition, add-back HRT will be recommended.

If you are using GnRH analogues for 2 years or more, a bone density (DEXA) scan will be recommended. A treatment break of 6 months may also be recommended.

How often will I need the injections?

For Prostap and Zoladex are available as a one month (four weekly) or three month (twelve weekly) preparation.

You might choose to start with a one month dose and then extend to three monthly, depending on your symptoms and side-effects. At each visit, the nurse administering your injection will tell you what dose you have had and when your next dose is due.

Will the injections interfere with my fertility?

You should not have this treatment if you are pregnant, trying to conceive or breastfeeding. You may be asked to provide a urine sample at your appointment to ensure you are not pregnant when the treatment is given.

Although the injections work by stopping the menstrual cycle, it is not licensed as contraception and therefore it is recommended that you use barrier contraception (e.g., condoms) for the duration of your treatment.

There is no long-term impact on fertility once the treatment is stopped and the menstrual cycle returns. However, a regular menstrual cycle may take weeks to months to return. The longer you use this treatment, the longer it may take for periods to return to normal.

Recommended sites

Royal College of Obstetricians and Gynaecologists:
www.rcog.org.uk

Endometriosis UK:
www.endometriosis-uk.org

Contacts

If you have any queries relating to appointments then please contact your consultant’s secretary.

Their number can be found on your appointment/correspondence letters.

Pelvic Pain and Endometriosis Specialist Nurse Telephone: 07817 022694

Email: Mia.white@nca.nhs.uk or Lyndsey.ferris@nca.nhs.uk