Polycystic Ovary Syndrome (PCOS) is a condition characterized by the overproduction of hormones, specifically oestrogen and androgens, which leads to the absence of ovulation. This hormonal imbalance results in symptoms of hyper-androgenism, such as acne and excessive body and facial hair growth. PCOS is also the most common cause of infertility due to the lack of ovulation.
The root cause of PCOS is often linked to abnormal communication between the hypothalamus, pituitary gland, and ovaries. In PCOS, there is an excess of luteinising hormone (LH), which triggers the overproduction of oestrogen and androgens, and a deficiency of follicular stimulating hormone (FSH), which is necessary for ovulation. As a result, instead of the normal cyclical hormone fluctuations involving progesterone, the levels of oestrogen and androgens remain consistently high, leading to an overall excess of these hormones.
One of the primary reasons for this hormonal imbalance is high insulin levels, which cause abnormal spikes in gonadotropin-releasing hormone (GnRH) from the hypothalamus. This, in turn, leads to an abnormal ratio of LH to FSH from the pituitary gland. Elevated insulin levels, along with genetic and epigenetic factors, contribute to the dysfunction of the pituitary-ovarian axis.
Interestingly, insulin resistance is a better predictor of PCOS than body size, explaining why even lean individuals with genetic insulin resistance can develop PCOS. Elevated insulin levels exacerbate the hormonal imbalance through several mechanisms:
- Decreasing SHBG (sex hormone-binding globulin): This protein normally binds hormones, so lower levels result in higher levels of free, biologically active hormones.
- Increasing ACTH action on the adrenal glands: This boosts the production of cortisol and androgens, worsening insulin resistance.
- Contributing to weight gain: This further exacerbates insulin resistance.
The interplay between increasing insulin and hormone levels creates a snowball effect. The key to managing PCOS lies in improving insulin sensitivity and production through lifestyle changes, such as regular exercise, a diet rich in nutrients and low in glycemic index carbohydrates, and limiting saturated fats. Medical treatments, like metformin, are also effective.
The cause of PCOS in the absence of insulin resistance remains a topic of debate. It is likely due to pituitary-ovary dysfunction from unknown causes or very mild insulin resistance. This is why metformin is often the first line of medical management to restore ovulation, regardless of body size. 💛