What is Polycystic Ovarian Syndrome (PCOS)?
PCOS is one of the most common endocrine disorders, with evidence that it may be genetic and run in families. The diagnosis is made if a woman has 2 or more of the following signs or symptoms in the absence of other problems:-
- infrequent or absent menstrual cycles or evidence of not ovulating
- Evidence of a typical polycystic pattern of the ovaries on Ultrasound scan
- Evidence or symptoms of excess male hormones( excess hair, greasy skin)
The exact cause of polycystic ovarian syndrome is uncertain but it is known to involve an inability of the ovaries to produce hormones in the correct proportions, leading to an inhibition of the usual mechanism that controls the development of mature follicles and prevents the release of these eggs (ovulation).
Why have I been prescribed Metformin?
You have been prescribed the drug Metformin because you have been diagnosed with polycystic ovarian disease (PCOS).
What is Metformin?
Metformin is a tablet that has been used for many years to treat older patients with Non Insulin Dependent Diabetes (NIDDM).
How does Metformin work?
One effect of PCOS is that the body is less sensitive to the hormone Insulin (that controls blood sugar level) and thus patients produce an excess of Insulin, resulting in the conversion of greater proportions of food energy into fat cells. The abnormal levels of Insulin and other hormones such as Oestrogen have also been shown to increase the amount of active male hormone Testosterone in the blood leading occasionally to symptoms of excess male hormones or androgens (excess hair and greasy skin).
Metformin makes the body more sensitive to the hormone Insulin and thus reduces the amount of insulin in the blood hopefully allowing the ovary to work more efficiently to allow ovulation and reduce the levels of free Testosterone.
Whilst Metformin is used in Diabetic patients to reduce high blood sugar levels to normal, it will not make sugar levels fall to low levels and so patients will not experience symptoms of low blood sugar ( Hypoglycaemia).
What else will help?
It is known that many patients with the tendency to PCOS and normal weight do not display any symptoms of the disease such as failure to ovulate or infrequent periods, whereas symptoms are much more likely to occur and be more severe in patients who are overweight especially patients who are classified as Obese (BMI>30). For patients who are overweight the best treatment is for Metformin to be used in addition to healthy eating, losing weight and regular exercise.
In our clinic we use metformin along with weight loss as our first line management for women with PCOS, and continue the use if you need to start fertility treatment such as invitro fertilisation. You can learn more about managing weight in our latest guide.
How successful is Metformin?
Metformin has been shown from studies to start ovulation in 45% of women with PCOS, who previous to treatment did not have periods or had very irregular periods. Metformin is much more successful in women who are not overweight with a significantly better chance of ovulating with Metformin Alone. When used alone patients do not need to have any extra careful monitoring as there is no extra risk of multiple pregnancy. For patients who do not ovulate with Metformin we would then advise starting formal Ovulation induction with Clomifene citrate, whilst continuing with Metformin (this has been shown to increase the effectiveness of treatment, and reduce multiple pregnancy rates.)
In the absence of any other causes of fertility problems such as low sperm count, endometriosis or blocked tubes, fertility is restored to normal and up to 75% of our patients who start ovulating would be expected to conceive with this treatment alone.
For patients with PCOS undergoing fertility treatment in the form of IVF/ICSI it has been shown that Metformin reduces the risk of the serious complication of Ovarian Hysperstimulation Syndrome (OHSS)
Metformin may also lower the risk of miscarriage or diabetes that develops in pregnancy (gestational diabetes).
What are the side effects of Metformin?
The most common side effects are:
- Nausea, loss of appetite, diarrhoea, abdominal bloating, metallic taste, and occasionally vomiting.
The side effects of Metformin usually decrease over time and for that reason we introduce the medication slowly with gradual increasing doses over 3 weeks. For patients who are still troubled with side effects in spite of this gradual build up you can either reduce the diose to a level that is tolerated or alternatively there is evidence that a special formulation (MR or Modified Release) may further reduce side effects and your GP may be willing to prescribe this.
There are no adverse side effects when taking Metformin in pregnancy and it has been demonstrated over many years to be very safe, and is now the first choice treatment option for diabetes that develops in pregnancy.
What is the dose?
We recommended that you start on one 500mgms tablet a day for one to two weeks , increasing at weekly to 2 weekly intervals to one 500mgms tablet twice a day and then increasing to a maintenance dose of 500mgms three times a day or 850mgms twice a day. We recommend that if a pregnancy is achieved you continue the metformin until you deliver the baby.
