Gout: an animated, cited guide

This page needs JavaScript for its animations. The outline and key answers are below, and every claim in the full version carries a numbered citation.

Not medical advice. Gout Companion is an educational synthesis of published literature. It does not replace a clinician.

What is in it

What gout is Who gets it, the numbers, and the four stages from high urate to tophi.
Where urate comes from Purines, xanthine oxidase, and how the kidney and gut handle urate.
Crystals vs serum urate Why crystals form above about 6.8 mg/dL and dissolve below the target.
A flare, hour by hour From a shed crystal to the NLRP3 inflammasome, interleukin-1β and neutrophils, then resolution.
Colchicine inside the cell From the pill to the neutrophil to the microtubule.
Treating a flare Colchicine, NSAIDs, glucocorticoids, IL-1 blockers and ice.
Colchicine dosing and safety Published doses, kidney function and drug interactions.
How urate-lowering drugs work Allopurinol, febuxostat, uricosurics and pegloticase.
Treat to target Titrating to below 6 mg/dL, and why flares rise in the first months.
Safety of urate-lowering drugs HLA-B*58:01, the CARES and FAST trials, interactions.
Diagnosis and the ACR/EULAR score Crystals under polarised light, imaging, and the 2015 classification calculator.
The differential Calcium pyrophosphate crystal arthritis, septic arthritis, cellulitis and others.
Gout, kidneys and heart Chronic kidney disease, stones, blood pressure and cardiovascular risk.
Living with gout Diet, alcohol, weight, other medicines and a flare plan.
Nursing care Assessment, giving the medicines, teaching and documentation.
Toward a cure Dissolving crystals for good, and the research pipeline.
History and people From podagra to polarised light and allopurinol.
Flashcards, quiz and glossary Revision for students.
Sources Every reference behind the app.

Part 1 · The disease

Crystals vs serum urate

Urate crystals grow only while serum urate stays above its saturation point of about 6.8 mg/dL, and they dissolve once it is kept below 6. Scrub through fifteen years of one imagined person, start treatment at year 9, then pick the urate level treatment reaches and how cool the joint is.

Urate on treatment

Joint temperature

Years

Schematic, not to scale. One imagined person, not a prediction. The fixed points are published: saturation at 6.8 mg/dL at 37 °C and 6.0 mg/dL at 35 °C, the < 6 mg/dL target, and tophus shrinkage speeding up in a straight line as on-treatment urate falls. The growth and shrink slopes are relative, because no study gives a rate in mm per month that applies here. ^{236,249,312,331}

Who forms crystals, and how fast they leave

Fifteen-year risk of gout by baseline urate

Individual-participant data from 4 US cohorts: 18,889 people and 212,363 person-years. Hazard ratios are adjusted and compared with a baseline urate < 6 mg/dL (< 360 µmol/L). The 15-year cumulative incidence was 1.1% (95% CI 0.9–1.4) below 6 mg/dL and 49% (31–67) at ≥ 10 mg/dL (≥ 595 µmol/L). Each dot is one person in 100. ⁸²

Crystals leaving joint fluid on treatment

18 men (11 knees, 7 first MTPs) were aspirated every 3 months after starting urate lowering. Median urate fell from 550 to 290 µmol/L (≈ 9.2 to 4.9 mg/dL) by 3 months. Crystals left every joint, after 3 to 33 months, and the time tracked how long the person had had gout (rs = 0.71, p < 0.01). The report does not give separate times for knees and toes. ³⁰⁸

Seeing the deposits

Finding	Who	Result	Source
Urate deposits on dual-energy CT of the feet	Asymptomatic, urate ≥ 540 µmol/L (≈ 9.1 mg/dL)	6/25 (24%)	⁷⁹
	Early gout (≤ 3 years)	11/14 (79%)	⁷⁹
	Late gout	16/19 (84%)	⁷⁹
Double-contour sign at the first MTP on ultrasound	50 asymptomatic hyperuricaemic people vs 52 normouricaemic controls	25% of joints vs none	³¹⁶
Double contour after sustained urate lowering	5 people followed 7–18 months	Gone in every joint where urate stayed < 6 mg/dL, not where it stayed ≥ 7 mg/dL	⁴¹¹
Crystals still in the knee	Urate ≤ 6 mg/dL for more than 12 months	7/16 knees (44%)	²³⁵
DECT deposits in people meeting remission criteria	On allopurinol ≥ 300 mg/day	44% in remission vs 73.6% not in remission	⁸³