PCOS Causes

Polycystic ovarian syndrome (PCOS) is a common endocrine abnormality that affects female hormonal levels. It is a problem that is most prevalent during the reproductive years.

Since PCOS primarily affects the female ovaries, it is regarded as a serious metabolic and reproductive disorder. This could result in ovarian cysts, excessive hair growth, menstrual abnormalities, and difficulty with conception. 

Women who have PCOS are at higher risk of developing serious health problems such as cardiovascular diseases, diabetes, high blood pressure, and endometrial cancer.

What is PCOS?

Polycystic ovary syndrome (PCOS) is a common condition that causes hormonal imbalance during the reproductive years. This usually happens when the ovaries start to produce abnormal levels of male sex hormones (androgens), which are found in small amounts in a female's body under healthy conditions.

Generally, the ovaries are responsible for producing and releasing an egg (ovum) in a process called ovulation. The ovaries contain a lifelong supply of tiny fluid-filled structures called follicles. To regulate the maturation of several premature eggs, the pituitary gland, located at the base of the brain, secretes hormones known as follicle-stimulating hormone (FSH) and luteinizing hormone (LH). As the follicles expand and mature, they secrete oestrogen into the bloodstream, causing the pituitary gland to release more LH to prepare for the release of the most mature egg.

Once an egg is mature, it is released from the ovary and travels through the fallopian tube, where it awaits fertilisation. If the mature egg is not fertilised, it is shed out of the body resulting in menstruation.

 In PCOS, the pituitary gland secretes abnormal amounts of luteinizing hormone, which disrupt the menstrual cycle. As a result, the follicles are unable to mature. In some cases, ovulation does not occur due to insufficient hormonal secretion. This can lead to the development of immature follicles into many fluid-filled cysts on the outer part of the ovary. These cysts can eventually release high amounts of androgens, causing irregular periods, unpredictable ovulation, and even infertility.

Despite the name of the condition, cysts are not necessarily present during PCOS. Sometimes, PCOS is also medically referred to as polycystic ovaries (PCO) or polycystic ovarian disease (PCOD).

PCOS is recognised as an important hormonal disorder among people assigned female at birth (AFAB) that typically occurs after puberty. According to a study, its prevalence is estimated to be between 4% and 20% globally.1

It is difficult to identify how many people AFAB experience PCOS. However, it is thought that PCOS nearly affects 1 in every 10 individuals in the UK.

Symptoms of PCOS

PCOS symptoms differ among people AFAB. It often starts after the first menstrual cycle. However, the symptoms can develop in later life as well. The most commonly known symptoms of PCOS include:

  • Abnormal menstrual cycle, including having irregular or no periods
  • Hirsutism - the excessive growth of facial and body hair (heavy hair growth on the arms, chest, and abdomen)
  • Severe acne
  • Skin tags - are often located on the neck or in the armpits
  • Hair loss or male-patterned baldness
  • Darkened skin patches near the underarms, neck, breast, and pelvic regions (acanthosis nigricans)
  • Ovarian cysts
  • Weight gain
  • Infertility

It is possible for some people AFAB to have no symptoms at all. Many people are not aware of the condition unless they tend to have trouble conceiving or gaining weight for no apparent reason.

The exact cause of PCOS remains to be understood

The exact reason for the development of PCOS is still not fully known. Some studies have indicated that it could be linked to certain factors such as lifestyle, family history, hormonal, obesity, stress, physical inactivity, infectious agents, toxins, and poor dietary choices.1,2

Hormonal abnormalities

PCOS typically throws certain hormones out of balance; this includes:

  • Overstimulation of luteinizing hormone (LH) prevents the maturation of eggs
  • Elevated levels of androgens (male sex hormones) interfere with the overall ovulation process. The cysts found in the ovary release high amounts of androgens, which cause menstrual irregularities. High amounts of androgens are also responsible for heavy facial and body hair growth
  • Decreased levels of sex hormone binding globulin (SHBG) – a protein that binds with testosterone to reduce its effects
  • High levels of prolactin

The changes in hormones during PCOS are not very well known. It's indicated that the issue may primarily involve the pituitary gland, ovaries, or other hormone-producing glands.

Abnormally high insulin

Insulin is one of the major hormones produced by the pancreas. It aids in the regulation of glucose levels in the bloodstream.

In PCOS, the body becomes resistant to the effects of insulin. Therefore, the body allows more production of insulin, resulting in high levels of the hormone. Such high amounts of insulin, along with elevated luteinizing hormone, cause the ovaries to release testosterone (androgen), which prevents the process of ovulation.

Due to insulin resistance, the body is unable to process insulin correctly, leading to high levels of glucose. The elevated amounts of sugar in the bloodstream may also contribute to diabetes and weight gain.

Elevated LH

High levels of luteinizing hormone typically interfere with ovarian function. A study has indicated that the cause of high LH levels is due to increased pituitary sensitivity to gonadotropin-releasing hormone (GnRH), which is a key regulator for the pituitary gland to release FSH and LH.3

Elevated testosterone

Normally, people AFAB only produce small amounts of male androgen. However, in PCOS, high levels of insulin and LH affect the ovaries, causing them to produce excessive amounts of testosterone, which suppresses the development of eggs. High testosterone contributes to increased hair growth, baldness, and severe acne.

Autoimmune issues

Although PCOS is typically an endocrine disorder, some studies have suggested a possible association with autoimmune diseases. Due to hormonal fluctuations and the hyperactivity of the immune system to produce more estrogen, several autoantibodies have been documented in PCOS. Studies have also shown the presence of thyroid autoimmune markers in PCOS patients.4


Polycystic ovarian syndrome is a common endocrine condition that affects females of reproductive age. It is considered a serious metabolic and reproductive disorder since it adversely impacts the ovaries of the reproductive system and overturns hormonal levels.

PCOS is one of the common causes of menstrual irregularities, increased hair growth, and infertility. The exact cause of PCOS is still not widely known. However, certain genetic and environmental factors, such as lifestyle, obesity, and poor diet, may contribute to the development of the condition. Although the symptoms of PCOS vary among individuals, identifying the symptoms and managing them could help improve quality of life.


  1. Jabeen A, Yamini V, Rahman Amberina A, Dinesh Eshwar M, Vadakedath S, Begum GS, et al. Polycystic Ovarian Syndrome: Prevalence, Predisposing Factors, and Awareness Among Adolescent and Young Girls of South India. Cureus. 2022 Aug 12;
  2. Ndefo UA, Eaton A, Green MR. Polycystic ovary syndrome: a review of treatment options with a focus on pharmacological approaches. P & T : a peer-reviewed journal for formulary management [Internet].
  3. Johansson J, Stener-Victorin E. Polycystic Ovary Syndrome: Effect and Mechanisms of Acupuncture for Ovulation Induction. Evidence-Based Complementary and Alternative Medicine [Internet]. 2013;2013:1–16.
  4. Mobeen H, Afzal N, Kashif M. Polycystic Ovary Syndrome May Be an Autoimmune Disorder. Scientifica [Internet]. 2016;2016:1–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871972/

Sadaf Ahmed

Master of Science - MSc, Physiology, Clinical & Molecular Hematology, Karachi University, Pakistan

Sadaf is an experienced writer who creates a quality and well-researched scripts particularly related to Health Sciences.

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