Gout

What is gout?

Gout is a form of inflammatory arthritis caused by hyperuricaemia: abnormally high uric acid levels in the blood. When uric acid exceeds its solubility limit (around 6.8 mg/dL), it crystallises into monosodium urate crystals that deposit in joints, tendons and surrounding tissues. An acute gout attack occurs when the immune system reacts to these crystals, causing intense inflammation. The classic presentation is sudden, severe pain in the big toe joint (first metatarsophalangeal joint), often waking the patient at night, with redness, swelling and warmth.

Uric acid blood test

Important: uric acid levels may be NORMAL or even LOW during an acute gout attack, because the inflammatory response causes uric acid to redistribute. A normal uric acid during an attack does not rule out gout. Recheck 2–4 weeks after the attack resolves.

A Normal Uric Acid Does Not Rule Out Gout

This is the single most useful thing to know about the uric acid test, and it is the opposite of what most people assume. A blood test taken during an acute attack can come back normal in someone who genuinely has gout, and a normal result is regularly used to dismiss the diagnosis.

The size of the effect is well documented. Across two trials of acute gout treatment covering 339 patients, 14% had a genuinely normal urate at presentation, and 32% had a level at or below 8 mg/dL during the attack. Attacks occurred even below the concentration at which urate crystallises.²

There are two reasons for this. Crystals that formed months or years ago are already sitting in the joint, and an attack is the immune system reacting to them — it does not require the blood level to be high at that moment. And during an attack, urate often shifts out of the blood, so the timing of the test works against you.

The same study showed why context matters: people already taking allopurinol had markedly lower urate during their attacks than those not taking it.² Being on treatment does not prevent every flare, particularly early on, and a flare while taking allopurinol is not evidence the drug has failed.

Where the diagnosis is genuinely uncertain, the definitive test is not a blood test at all — it is examining fluid drawn from the joint for urate crystals under a microscope, which also distinguishes gout from a joint infection, an entirely different emergency that can look similar.

Joints commonly affected by gout

What causes high uric acid?

Diet changes to lower uric acid

• Limit red meat, organ meats (liver, kidney) and shellfish (highest purine content)
• Avoid beer and spirits; moderate wine consumption
• Drink at least 2 litres of water daily (dilutes uric acid)
• Increase low-fat dairy (milk, yoghurt): shown to lower uric acid
• Eat cherries or tart cherry juice: evidence supports modest uric acid reduction
• Avoid high-fructose corn syrup (soft drinks, fruit juices)
• Maintain a healthy weight: obesity doubles gout risk

Medications for gout

Questions to ask your doctor

• Should I start uric acid-lowering therapy (allopurinol)?
• What uric acid target should I aim for?
• Which foods are highest in purines that I should avoid?
• Is my diuretic worsening my gout?
• Do I need a joint aspiration to confirm gout and rule out infection?