Diagnosis of gout

The diagnosis of gout is made through several steps.
The combination of typical symptoms, clinical examination, and laboratory values is essential.

  1. Medical history (Anamnesis)

The doctor may ask about:

  • How the pain began (usually suddenly, often at night)
  • Which joints are affected
  • Previous similar attacks
  • Dietary habits (e.g., alcohol, meat consumption)
  • Medications (e.g., diuretics)
  1. Physical examination

Typical findings:

  • Markedly red, swollen, very tender joint
  • Warmth over the joint
  • Limited mobility

→ A classic finding at the base joint of the big toe is often highly suggestive.

  1. Blood tests
  • Uric acid level (may be elevated – but note: during an acute attack, it can be normal!)
  • Inflammatory markers: CRP, ESR, leukocytes often elevated

→ A high uric acid level supports the diagnosis but does not prove it alone.

  1. Joint aspiration (Gold standard)

If uncertainty exists, the doctor can withdraw fluid from the inflamed joint.

Under the microscope, you find:

  • Needle-shaped uric acid crystals (urate crystals)

This is definitive proof of gout.

  1. Imaging (used less frequently)
  • Ultrasound: typical “double contour sign” caused by urate deposits
  • X-ray: used in later stages; shows joint damage
  • Dual-energy CT (DECT): can directly visualize uric acid crystals

Important

The diagnosis is usually based on the typical course of pain + affected joint + elevated uric acid level.
A joint aspiration is especially necessary when infection must be ruled out.

Uric Acid

Here are the most important points summarized clearly:

Normal Uric Acid Levels

Values vary slightly by laboratory, but typically:

Men

  • 3.5 – 7.0 mg/dL (approx. 200–420 µmol/L)

Women

  • 2.5 – 6.0 mg/dL (approx. 150–360 µmol/L)
    (After menopause, levels often rise.)

Can gout attacks occur with normal uric acid levels?

Yes — this is possible and even surprisingly common.

Why?

During an acute gout attack, uric acid levels in the blood often drop, because many uric acid crystals are bound inside the joint.
This can make the blood level appear normal or even low.

How common?

  • About 30–50% of patients have normal uric acid levels during an acute attack.
  • A normal value does not exclude gout.

Therefore, the diagnosis is not based on uric acid alone.

Important Notes

  • Uric acid levels are most reliable between attacks.
  • When in doubt, analysis of joint fluid (crystal detection) is the most accurate test.
  • Normal blood levels during an attack are especially common in:
    • First-time attacks
    • Patients who have been drinking a lot of fluids
    • Patients with fever or other inflammatory conditions