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How it is diagnosed, and what gets ruled out first

What a clinician is actually doing when she orders blood tests before agreeing you have PCOS.

Lesson 2 of 5

12 min Text

What this lesson says

  • Two of three criteria, with other causes excluded, is the widely used approach
  • A scan alone is not a diagnosis, and a normal testosterone does not rule PCOS out
  • Thyroid disease, raised prolactin and some adrenal conditions are excluded first because they are treated differently
  • Because two of three is enough, two women with PCOS can share almost no symptoms

This is general education. It is not advice about your own situation, and it does not replace seeing a clinician.

Written lesson.
  1. 1. The widely used approach asks for two of three features. Irregular or absent ovulation, usually shown by cycles that are persistently long, unpredictable or absent. Signs of raised androgens, either visible on examination or measured on a blood test. And polycystic-looking ovaries on ultrasound.
  2. 2. Two of those three, with other explanations excluded. That last clause is not a formality. Thyroid disease, raised prolactin and certain adrenal conditions can produce a very similar picture, and all of them are treated completely differently. Getting the wrong one means years of the wrong treatment.
  3. 3. That is why a careful clinician orders blood tests before accepting the diagnosis rather than after it. If nobody checked your thyroid and prolactin, that is a reasonable thing to ask about.
  4. 4. Two common misunderstandings. A scan finding on its own is not enough, and a great many women with entirely regular cycles have ovaries that look polycystic. And a normal testosterone result does not rule PCOS out — visible signs on examination count as evidence of raised androgens in their own right.
  5. 5. One consequence of the two-of-three rule is worth sitting with: two women can both accurately be told they have PCOS and have almost nothing in common symptomatically. One has irregular cycles and a scan finding and no skin changes at all; another has regular cycles, acne and raised androgens. That is why there is no single treatment, which is the subject of the next lesson.

All lessons in this course

  1. 1 What PCOS is, and what the name gets wrong 10 min
  2. 2 How it is diagnosed, and what gets ruled out first 12 min Reading now
  3. 3 Treatment is aimed at goals, not at the condition 13 min
  4. 4 Lifestyle: what the evidence supports, and what it does not 12 min
  5. 5 Questions to take to your own clinician 8 min

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