Gout: the crystal disease, and why your uric acid number isn't the whole story

Gout is a form of arthritis caused by tiny crystals of uric acid, a normal waste product carried in your blood, settling inside a joint and triggering a sudden, severe attack of inflammation. The crystals are the disease; the blood level is only the risk. You can run a high uric acid level for years and never get gout, and the level can read normal in the middle of an attack, so gout is confirmed by the attack itself, ideally by finding crystals in fluid drawn from the joint, not by the blood number alone.

What is gout?

Gout happens when uric acid, the end product your body makes when it breaks down purines (building blocks found in your own cells and in food), builds up in the blood and starts to crystallize. Above roughly 6.8 mg/dL, uric acid stops fully dissolving and can settle out as solid needles called monosodium urate crystals, usually written MSU. ² When those crystals collect in a joint and the immune system reacts to them, the joint turns red, hot, swollen, and painful. That reaction is a gout attack. ²

The number itself, the ranges for men and women, and how to lower it belong to the uric acid page; gout is what happens when the crystals form. And if your lab's 'normal' range does not line up with the treatment target, that gap is what reference ranges explain, not a lab error.

Does high uric acid always mean gout?

No. High uric acid, called hyperuricemia, is necessary for gout but not enough to cause it on its own. Most people with a high level never have an attack. ³

The gap runs the other way too. During an acute flare, uric acid in the blood often falls, so a level that looks normal on the day your joint is screaming does not clear you of gout. ⁴ The reliable measurement is taken a few weeks after the attack settles.

About 1 in 5 US adults has hyperuricemia, yet gout affects about 3.9% of adults, roughly 9.2 million people. ¹ Having the number is common; having the disease is not.

What are the symptoms of gout?

A gout attack tends to arrive fast and hard, often overnight. The joint becomes red, hot, swollen, and so tender that the weight of a bedsheet can be too much. Pain usually peaks within 12 to 24 hours of starting. ⁴

About half of first attacks strike the base of the big toe, a presentation old texts call podagra; over time the ankles, knees, wrists, and fingers can be involved too. ⁴ Early attacks often settle on their own over a few days to two weeks, even without treatment, which is part of why gout is easy to dismiss until it comes back.

• Sudden, severe pain in one joint, frequently the big toe
• A joint that looks red or purplish and feels hot to the touch
• Swelling and tightness, with shiny skin over the joint
• Skin so sensitive that light touch hurts
• Attacks that often begin at night and peak within a day

How is gout diagnosed?

The definitive test is to draw a little fluid from the affected joint and look at it under a polarizing microscope. If needle-shaped monosodium urate crystals are there, it is gout, whatever the blood level is doing. ⁴ Because that certainty matters, a clinician may aspirate the joint (draw fluid from it) rather than diagnose on symptoms alone.

Serum uric acid, the blood test, is cheap and often already sitting in a routine metabolic panel, but on its own it can mislead in both directions: high without disease, or normal during a flare. ³⁴ If a level is drawn during an attack and comes back normal, ask about rechecking it a few weeks later once the joint has calmed.

Only joint fluid separates these three with certainty, which is another reason a first hot, swollen joint is worth a same-day look rather than a guess.

What causes gout, and who is at risk?

Gout builds on a high uric acid level, and most of the time that level is high because the kidneys are clearing too little of it, not because the body is making too much. The kidneys handle roughly 70% of uric acid removal, so anything that lowers kidney filtering tends to raise urate. ² To see how well your kidneys are clearing, the creatinine (a waste product your kidneys filter out) and eGFR (an estimate of your kidneys' filtering speed) markers are where that story lives, all part of the kidney panel.

On top of that baseline, specific triggers can tip a susceptible joint into a flare:

• Big servings of red meat, organ meats, or shellfish
• Beer and spirits, especially a heavy session
• Sugary sodas and fruit juice high in fructose
• Dehydration, or a sudden crash diet or fast
• Starting certain water pills (diuretics) used for blood pressure
• A minor injury, surgery, or another acute illness

Risk is higher in men, in women after menopause (before menopause, estrogen helps the kidneys clear urate, so women tend to run lower), and in people with reduced kidney function, obesity, high blood pressure, diabetes, or a family history of gout. ²

What foods should you avoid with gout?

Food matters, though less than the internet suggests. The pattern with the best evidence: meat and seafood raise gout risk, low-fat dairy lowers it, and purine-rich vegetables like spinach and beans do not raise risk at all. ⁵ Sugary drinks and fructose also raise uric acid and gout risk, a link established more recently than the one for meat and seafood. ⁶

Eating well lowers uric acid by only about 1 mg/dL, real but modest, and far less than urate-lowering medication achieves. ⁸ For someone with frequent attacks or crystal deposits, diet supports treatment; it rarely replaces it. How far diet, weight, and alcohol move the number is covered on the uric acid page.

How is gout treated?

Treatment has two separate jobs: calming the current attack, and lowering uric acid over the long term so crystals stop forming and existing ones dissolve. Both involve prescription medicines, and which ones, at what point, is a clinician's decision, not something to start or adjust on your own.

For the long-term job, guidelines use a treat-to-target approach: pick a uric acid goal and adjust medication until the blood level stays under it. The 2020 American College of Rheumatology guideline sets that target below 6 mg/dL for all patients on urate-lowering therapy. ³ European (EULAR) guidance goes further for severe gout or visible lumps of crystals called tophi, setting a lower goal below 5 mg/dL to dissolve those deposits. ⁷

We conditionally recommend against initiating pharmacologic urate-lowering therapy for patients with asymptomatic hyperuricemia.FitzGerald et al., 2020 ACR Gout Guideline

That last point is why a high uric acid number with no attacks, no tophi, and no kidney stones is usually watched rather than medicated. ³

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