insulin levels in the bloodstream can suppress the production of SHBG so that the amount of unbound (active) testosterone is raised – the reason why some women with high insulin levels (common if you’re overweight) can have signs of testosterone excess even when tests reveal a normal level in the blood.
HOW MUCH IS TOO MUCH?
The normal blood testosterone level in women should be around 0.5–3.5 nmol per litre (a small measure of a substance in a solution); in men usually 15–30 nmol per litre. Women with PCOS tend to have a testosterone level of 2.5–5.0 nmol per litre. If the level goes higher than 5.0 nmol then other problems such as congenital adrenal hyperplasia and ovarian tumours need to be ruled out.
Mild testosterone excess in women can cause symptoms such as acne, hirsutism and alopecia (thinning hair on the head) and these symptoms are often called androgenization or hyperandrogenism. It’s important to point out, though, that testosterone levels in women with PCOS don’t usually get so high as to cause a condition called virilization, which is when the voice gets deeper, breasts shrink and the clitoris enlarges.
TOO MUCH LH?
High blood levels of the pituitary hormone LH are also commonly found in women with PCOS, and higher-than-normal LH levels can trigger the production of testosterone and the familiar symptoms of PCOS.7
The high levels of LH may be due to lack of ovulation, as both oestrogen and progesterone inhibit the production of LH, but some women with PCOS and regular ovulations also have high LH levels, indicating that in some cases there may be a problem with the pituitary gland itself or with its ability to interact with the ovaries.
BLAME IT ON THE INSULIN!
In the last few years, research8, 9 has discovered that a condition known as insulin resistance plays an important role in the cause of PCOS. Major reviews on the subject suggest that up to 70 per cent of women with PCOS who are overweight can have insulin resistance, and around 30 per cent of women who are slim can have it, too.
Women with insulin resistance have raised levels of insulin in their bloodstream, and high levels of insulin have been shown to stimulate the ovaries to produce more testosterone and lower blood levels of SHBG, resulting in higher and more active levels of testosterone.
‘I only found out I had insulin resistance as well as PCOS when I got pregnant. Tests revealed that my blood sugar levels were all over the place.’
Alice, 36
WHAT IS INSULIN RESISTANCE?
Insulin is a powerful hormone released by your pancreas in response to eating food – especially carbohydrates. It transports sugar out of the blood and into muscle, fat and liver cells, where it’s converted to energy or stored as fat. Many women with PCOS have insulin resistance. This means that the process of getting the sugar out of the blood and into the cells is defective – the cells are ‘resistant’ to insulin. The pancreas must secrete more and more insulin to get sugar out of the blood and into the cells. High levels of insulin, or hyperinsulinaemia, can trigger weight gain, problems with ovulation, an increased risk of diabetes, difficulty losing weight and an increased risk of heart disease by raising LDL (the unhealthy cholesterol) and triglyceride levels and decreasing HDL (the healthy cholesterol).
THYROID PROBLEMS
Your thyroid is a gland at the bottom of your neck. It weighs less than an ounce but has an enormous effect on your health. All aspects of your metabolism, from the rate at which your heart beats to how quickly you burn calories, are regulated by your thyroid hormones.
If your thyroid releases the proper amount of hormones, body systems function normally. But if your thyroid doesn’t produce enough it causes hypothyroidism (underactive thyroid), and upsets the delicate balance of chemical reactions in your body. Symptoms include fatigue, weight gain, irregular periods and high blood pressure (sound familiar?). If you’re overweight and have irregular periods and insulin resistance, it seems your risk of developing hypothyroidism is higher.
Many of the symptoms of hypothyroidism correspond with the symptoms of PCOS, and there do seem to be strong links between the two conditions. At present there just isn’t enough evidence to suggest that thyroid problems may have a causal link with PCOS, but early research10 suggests there may well be a connection of some kind.
An interesting study illustrated this by investigating the relationship between polycystic ovary syndrome, hypothyroidism and insulin-resistance and how, by submitting patients to a specific therapy for any one of these three problems, the researchers were able to obtain an improvement in the other associated conditions.11
This study suggests that there are several ways to improve PCOS symptoms and increase fertility. If a single therapy can be effective, a combination might be even better.
THE CORTISOL CONNECTION
There may also be a link between PCOS and the production of the stress hormone cortisol. Studies12 have indicated that high testosterone levels associated with PCOS could be caused by a fault in the way the body produces Cortisol. This is the active form of the hormone released into the body by the adrenal gland to help it cope with stress and is turned into cortisone, the inactive form, by enzymes in the body. Researchers have found that some women with PCOS don’t have these enzymes. This means their bodies cannot process cortisol properly, causing higher levels of testosterone to be produced.
This suggests that stress may play a part in the development of PCOS. If you’re under stress your adrenal glands release the stress hormones – adrenaline and cortisol, as well as testosterone – to help you cope with that stress. If there’s a problem with the conversion of cortisol, you produce too much testosterone and this makes your symptoms worse and drives your body towards the classic PCOS symptoms of insulin resistance, weight gain and irregular periods. More research needs to be done, but knowing that stress may be a contributory factor can help you to take steps to ‘stress-proof’ your life, and you can do this with our action plan on page 266.
THE ENDOCRINE WEB
All these hormone theories – insulin, testosterone, LH, cortisol and thyroid problems – are in fact linked. This is because the endocrine (hormone) system regulating your blood sugar and insulin levels, as well as your sex hormones and stress hormones, is a sensitive web of interconnections. If one hormone is out of kilter, the others will be affected, too.
‘We know that normal ovulation requires the perfect synchronization of hormones in the body. PCOS causes shifts in hormone levels, rendering normal ovulation unlikely. The lack of ovulation is largely to blame for the infertility aspect of PCOS, while the hormone imbalance is responsible for the associated symptoms of unwanted hair growth and acne.’13
Clearly in PCOS there are hormonal imbalances, but we still don’t know which one is ultimately responsible for triggering
