PCOS: Causes, Symptoms, and Diagnostic Tests Explained

Women’s Health

• June 16, 2025

Understand what PCOS is, its symptoms, and the essential hormonal and metabolic tests used for diagnosis. Early testing is key to managing Polycystic Ovary Syndrome effectively.

Polycystic Ovary Syndrome (PCOS) is one of the most common hormonal disorders affecting women of reproductive age. It is a complex condition that impacts the ovaries, hormone levels, menstrual cycles, metabolism, and often fertility.

Despite its name, not all women with PCOS have cysts on their ovaries, and not all ovarian cysts indicate PCOS. The condition is primarily diagnosed based on hormonal imbalances and specific clinical signs.

What Is PCOS?

PCOS occurs when a woman's ovaries produce an abnormal amount of androgens (male hormones), which can interfere with ovulation and hormone regulation.

The exact cause of PCOS is unknown, but it’s believed to involve a combination of:

Insulin resistance
Hormonal imbalance
Genetic predisposition

Women with PCOS may have trouble ovulating regularly, resulting in irregular periods or difficulty getting pregnant. Over time, PCOS can also lead to complications such as type 2 diabetes, high cholesterol, and endometrial cancer.

Common Symptoms of PCOS

Symptoms of PCOS vary from person to person. Some women experience only mild signs, while others face more significant hormonal and metabolic effects.

Menstrual & Reproductive Symptoms

Irregular or missed periods
Heavy or prolonged bleeding
Difficulty conceiving (infertility)
Ovarian cysts (seen on ultrasound)

Hormonal Symptoms

Excess facial or body hair (hirsutism)
Persistent acne or oily skin
Hair thinning or scalp hair loss
Darkened skin patches (especially around neck or underarms)

Metabolic Symptoms

Unexplained weight gain or obesity
Insulin resistance or elevated blood sugar
Fatigue or low energy levels
Increased risk of type 2 diabetes and high cholesterol

How Is PCOS Diagnosed?

PCOS is diagnosed using a combination of clinical symptoms, blood tests, and ultrasound imaging. The widely accepted Rotterdam criteria state that a diagnosis requires any two of the following three:

Irregular or absent ovulation
Signs of elevated androgens (acne, hair growth, or high testosterone)
Polycystic ovaries on ultrasound

Key Diagnostic Tests for PCOS

1. Hormonal Blood Tests

These tests assess reproductive hormone levels and help rule out other causes.

LH (Luteinizing Hormone): Often elevated in PCOS; LH:FSH ratio > 2:1 is common
FSH (Follicle Stimulating Hormone): May be low or normal
Total and Free Testosterone: Typically elevated in PCOS
DHEA-S: Elevated levels indicate adrenal androgen excess
SHBG (Sex Hormone Binding Globulin): Often decreased, leading to more active testosterone
Prolactin & TSH: To rule out thyroid disorders and prolactinomas, which can mimic PCOS

2. Metabolic and Insulin Resistance Tests

PCOS is closely linked to metabolic dysfunction.

Fasting Insulin & Glucose: High fasting insulin suggests insulin resistance
HOMA-IR Calculation: Assesses insulin sensitivity
HbA1c: Reflects long-term blood sugar control
Oral Glucose Tolerance Test (OGTT): Assesses how well the body processes glucose
Lipid Profile: PCOS often coexists with high LDL and triglycerides, and low HDL

3. Pelvic Ultrasound

May reveal enlarged ovaries with multiple small follicles arranged in a “string of pearls” pattern
12 or more follicles (2–9 mm) or increased ovarian volume (>10 cm³) supports diagnosis
Note: Ultrasound is supportive, not mandatory for diagnosis

Summary Table: Core Tests Used to Diagnose PCOS

Test	Assesses	PCOS Pattern
LH / FSH	Ovulatory hormone levels	LH:FSH ratio > 2:1
Total / Free Testosterone	Androgen excess	Elevated
DHEA-S	Adrenal androgens	May be elevated
SHBG	Active androgen regulation	Often decreased
TSH & Prolactin	Rule out other hormonal disorders	Usually normal in PCOS
Fasting Insulin & Glucose	Insulin resistance	Elevated insulin
OGTT / HbA1c	Glucose metabolism	Impaired glucose tolerance
Lipid Profile	Metabolic health	High LDL / Triglycerides, Low HDL