Polycystic Ovary Syndrome (PCOS) is a super common endocrine disorder that we see all the time in clinical practice. Since you're prepping for the UKMLA AKT, it's really important to focus on the NICE guidelines and the specific diagnostic criteria used here in the UK.

Let's break this down into the "Big Three": how we diagnose it, how we investigate it, and how we manage it.

1. The Rotterdam Criteria

To make a diagnosis of PCOS, you need at least two out of the three following criteria (after excluding other causes like thyroid dysfunction or adrenal hyperplasia):

1. Oligovulation and/or Anovulation: Usually presenting as irregular or absent periods.
2. Hyperandrogenism: This can be clinical (hirsutism, acne, male-pattern hair loss) or biochemical (raised testosterone or Free Androgen Index on bloods).
3. Polycystic Ovaries on Ultrasound: Defined as $\ge$ 12 follicles (measuring 2-9mm) in either ovary OR an increased ovarian volume (>10ml).
   • Note: Ultrasound isn't usually recommended for diagnosis in adolescents as multi-follicular ovaries are common during puberty.

2. Investigations

When a patient presents with suspected PCOS, we need to confirm the diagnosis and rule out "mimics."

• Blood Tests (Day 2-5 of cycle if possible):
  • Total Testosterone & SHBG: To calculate the Free Androgen Index (FAI).
  • LH and FSH: You'll often see a raised LH:FSH ratio (classically 2:1 or 3:1), though this isn't part of the formal criteria anymore.
  • Progesterone: Taken on Day 21 to check for ovulation.
  • Exclude other things: Check TSH (thyroid), Prolactin (prolactinoma), and sometimes 17-hydroxyprogesterone (if you suspect late-onset CAH).
• Imaging:
  • Pelvic Ultrasound: Preferably transvaginal for better detail of the follicles.
• Metabolic Screening:
  • Check BMI, Blood Pressure, and an Oral Glucose Tolerance Test (OGTT) or HbA1c, as these patients have a high risk of Type 2 Diabetes.

3. Management

Management is very much "symptom-led" and depends on whether the patient wants to conceive.

• General/Lifestyle (First Line for everyone!):
  • Weight loss: Even a 5-10% reduction in weight can restore ovulation and improve insulin sensitivity.
• Menstrual Irregularity & Endometrial Protection:
  • If they have <4 periods a year, they are at risk of endometrial hyperplasia.
  • COCP: Regulates cycles and protects the endometrium.
  • Cyclical Progestogens: If the COCP is contraindicated.
  • Mirena IUS: Great for endometrial protection.
• Hirsutism and Acne:
  • COCP: Specifically ones like Dianette (co-cyprindiol), though watch out for VTE risk.
  • Topical Eflornithine: For facial hair.
• Infertility (Specialist Management):
  • Letrozole is now often first-line (over Clomifene) to induce ovulation.
  • Metformin: Can help with insulin resistance and sometimes helps ovulation.

I'll pull up some high-yield lessons and a flowchart to help you visualize the diagnostic pathway!