Introduction
Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting women
of reproductive age, affecting 10% of women.1
The pathophysiology of PCOS involves excessive androgen production and multiple ovarian
cysts. Consequently, the main clinical features include anovulatory infertility, acne and
hirsutism, irregular menstrual cycles, obesity and increased long term risks of cardiovascular
events and endometrial cancer.
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Aetiology
The aetiology of polycystic ovary syndrome is largely unknown and multifactorial. The genetic
inheritance of PCOS is heterogeneous and complex. However, it appears to be inherited in an
autosomal dominant fashion. Post-natal obesity appears to be the leading environmental
contributor.1
The pathophysiology of PCOS relates to excess androgen production, and this is usually due
to one or both of:
● Excess LH (luteinising hormone) production: the anterior pituitary releases
gonadotropin in response to gonadotropin-releasing hormone. This leads to excess
androgen production by the ovaries.
● Hyperinsulinemia and insulin resistance: excess insulin in the bloodstream promotes
androgen production by the ovaries. Hyperinsulinemia may stimulate the ovary to over-
produce testosterone and prevent the follicles from growing normally to release eggs.
This causes the ovaries to become polycystic.
These are the most common hormonal abnormalities found in PCOS.
Most women with PCOS have “cysts” found on their ovaries. These are immature follicles
which have had their ovulation phase arrested. This occurs due to an elevated baseline of LH
and lack of LH surge (as in a normal menstrual cycle).3
It is important to note there is a difference between the radiological finding of “polycystic
ovaries” and the biochemical disturbances of polycystic ovarian syndrome. Each of these can
exist in the absence of the other.
Risk factors
, Risk factors for polycystic ovary syndrome include:1
● Obesity
● Diabetes mellitus
● Family history of PCOS
● Premature adrenarche (early onset of pubic hair)
Clinical features
History
PCOS usually presents in a woman around puberty, up to mid-20s.3
Typical symptoms include:
● Hirsutism: excessive hair growth in women, especially affecting the face, chest and
back. Hirsutism is the most common symptom, present in 60% of women with PCOS.3
● Infertility
● Acne
● Menstrual cycle disturbance: manifesting as either oligomenorrhoea (reduction in
menstrual bleeding, defined as <9 periods per year) or amenorrhoea (no menstrual
bleeding)
● Obesity and weight gain
● Alopecia
● Depression and other psychological disorders
Clinical examination
Hirsutism is the most characteristic examination finding.3
Other clinical findings include the consequences of hyperandrogenism:
● Acne
● Hair loss and male pattern baldness
Women with PCOS also have an increased risk of metabolic syndrome resulting in:
● Hypertension
● Obesity
● Acanthosis nigricans: as a result of insulin resistance (Figure 1)
Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting women
of reproductive age, affecting 10% of women.1
The pathophysiology of PCOS involves excessive androgen production and multiple ovarian
cysts. Consequently, the main clinical features include anovulatory infertility, acne and
hirsutism, irregular menstrual cycles, obesity and increased long term risks of cardiovascular
events and endometrial cancer.
You might also be interested in our medical flashcard collection which contains over 1000
flashcards that cover key medical topics.
Aetiology
The aetiology of polycystic ovary syndrome is largely unknown and multifactorial. The genetic
inheritance of PCOS is heterogeneous and complex. However, it appears to be inherited in an
autosomal dominant fashion. Post-natal obesity appears to be the leading environmental
contributor.1
The pathophysiology of PCOS relates to excess androgen production, and this is usually due
to one or both of:
● Excess LH (luteinising hormone) production: the anterior pituitary releases
gonadotropin in response to gonadotropin-releasing hormone. This leads to excess
androgen production by the ovaries.
● Hyperinsulinemia and insulin resistance: excess insulin in the bloodstream promotes
androgen production by the ovaries. Hyperinsulinemia may stimulate the ovary to over-
produce testosterone and prevent the follicles from growing normally to release eggs.
This causes the ovaries to become polycystic.
These are the most common hormonal abnormalities found in PCOS.
Most women with PCOS have “cysts” found on their ovaries. These are immature follicles
which have had their ovulation phase arrested. This occurs due to an elevated baseline of LH
and lack of LH surge (as in a normal menstrual cycle).3
It is important to note there is a difference between the radiological finding of “polycystic
ovaries” and the biochemical disturbances of polycystic ovarian syndrome. Each of these can
exist in the absence of the other.
Risk factors
, Risk factors for polycystic ovary syndrome include:1
● Obesity
● Diabetes mellitus
● Family history of PCOS
● Premature adrenarche (early onset of pubic hair)
Clinical features
History
PCOS usually presents in a woman around puberty, up to mid-20s.3
Typical symptoms include:
● Hirsutism: excessive hair growth in women, especially affecting the face, chest and
back. Hirsutism is the most common symptom, present in 60% of women with PCOS.3
● Infertility
● Acne
● Menstrual cycle disturbance: manifesting as either oligomenorrhoea (reduction in
menstrual bleeding, defined as <9 periods per year) or amenorrhoea (no menstrual
bleeding)
● Obesity and weight gain
● Alopecia
● Depression and other psychological disorders
Clinical examination
Hirsutism is the most characteristic examination finding.3
Other clinical findings include the consequences of hyperandrogenism:
● Acne
● Hair loss and male pattern baldness
Women with PCOS also have an increased risk of metabolic syndrome resulting in:
● Hypertension
● Obesity
● Acanthosis nigricans: as a result of insulin resistance (Figure 1)
