GOUT

✓ Medically ReviewedDISEASEID: MDBT0139🚨 TRIAGE: URGENTICD-10: M10.9

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Definition

CLINICAL DEFINITION

Gout is inflammatory arthritis (joint inflammation) from monosodium urate crystals (needle-shaped urate deposits). It follows persistent hyperuricaemia (high blood urate above saturation). Acute flares cause abrupt severe pain with swelling and redness. Chronic disease forms tophi (firm urate lumps under skin) with joint damage. Kidney stones (hard urine minerals) and reduced kidney function often coexist.

IN PLAIN ENGLISH

Urate is waste in blood. Too much forms sharp crystals. Crystals settle in joints. Joints swell and hurt a lot. Big toe is hit first. Care can ease pain and stop harm.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Gout is not osteoarthritis (wear-and-tear joint wear with age). It is not septic arthritis (germ invasion with fever and pus) despite similar redness. It is not pseudogout (calcium crystal arthritis with different deposits). It is not cellulitis (skin infection without joint crystals). Brief ache without crystal proof or urate context is also excluded.

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Word Breakdown

gutt-

=drop from Latin gutta meaning drop

Literal Meaning: drop referring to humour dropping into joint

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Abbreviations

MSU=Monosodium urate - needle-shaped crystal that deposits in joints in gout

ACR=American College of Rheumatology - body that co-develops gout classification criteria

EULAR=European Alliance of Associations for Rheumatology - body that co-develops gout classification criteria

NSAID=Non-steroidal anti-inflammatory drug - pain-relief drug used for gout flares

CKD=Chronic kidney disease - long term kidney failure that impairs urate clearance

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Synonyms & Variants

Podagra›Gouty arthritis›Tophaceous gout›

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Category-Specific Context

Gout is a Disease because it is a distinct entity with cause, course and treatment. It is not a single Symptom (patient complaint) or Sign (exam finding). It has acute flares and chronic deposition phases. It links metabolism with joints and kidneys. Management targets flares plus long term urate burden.

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Clinical Context & Usage

CLINICAL SETTINGS

Primary Care for Flare and PreventionEmergency Department for Hot JointRheumatology Clinic for Tophaceous DiseaseNephrology Clinic for Stones and Kidney DiseaseInpatient Medical Ward for Severe Flare

USAGE & DOCUMENTATION NOTES

Use gout for crystal-proven or typical acute arthritis with hyperuricaemia (high blood urate). State joint pattern and always exclude septic arthritis (joint infection needing drainage). Record serum urate (blood urate test) noting it may fall during flare. Describe tophi (firm urate lumps) with stones and triggers. List drugs that raise urate with kidney function.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Persistent hyperuricaemia (high blood urate) exceeds saturation and forms monosodium urate crystals (needle-shaped deposits). Crystals settle in joints with tendons and bursae (fluid-filled cushions). Crystals trigger NLRP3 inflammasome (immune sensor complex) with interleukin-1 release (inflammation signal). Neutrophils (infection-fighting white cells) flood in causing intense pain and swelling. Repeated flares build tophi (firm urate lumps) with cartilage (smooth joint cover) and bone erosion. Kidney handling governs stones and chronic kidney disease (long term kidney failure).

PRIMARY CAUSES

Reduced kidney excretion of urate

Kidneys clear less urate so blood urate rises and crystals deposit in joints

Chronic kidney disease (long term kidney failure)

Falling filtration lowers urate clearance and raises saturation with deposition

High cell turnover including psoriasis and myeloproliferative states

Extra purine (cell building block) breakdown creates more urate than kidneys can clear

High purine diet with alcohol and fructose excess

More substrate plus reduced excretion raises blood urate and triggers flares

Volume depletion (low body fluid) with fasting or diuresis

Concentrated blood with reduced clearance favours crystal formation and flare

Acute illness, joint trauma or surgery

Stress with local change mobilises deposits and sparks intense inflammation

Obesity with metabolic syndrome (weight, pressure and sugar cluster)

Insulin resistance (poor sugar control) lowers kidney urate clearance and raises production

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Drug-Induced Causes

💊 Thiazide diuretics (bendroflumethiazide, indapamide) ↗

Mechanism: Reduce kidney urate clearance so blood urate rises and crystals form

→ Review indication with prescriber, consider alternative pressure drug, monitor urate and kidney function, treat flare separately

💊 Loop diuretics (furosemide, bumetanide) ↗

Mechanism: Cause volume loss with reduced kidney urate excretion and higher blood urate

→ Assess fluid status with prescriber, use lowest effective dose or alternative, monitor urate with flare cover when starting urate lowering

💊 Ciclosporin ↗

Mechanism: Impairs kidney urate handling and raises blood urate with crystal deposition

→ Coordinate with transplant team, monitor levels with kidney function, tailor gout therapy and avoid kidney-harming pain drugs

💊 Tacrolimus ↗

Mechanism: Reduces kidney urate clearance and favours hyperuricaemia (high blood urate)

→ Liaise with transplant team, monitor kidney function with urate, adjust gout plan and avoid interacting drugs

💊 Pyrazinamide ↗

Mechanism: Blocks kidney tubular secretion of urate and raises blood urate sharply

→ Continue tuberculosis course as directed, monitor urate, manage flares with specialist input

💊 Ethambutol ↗

Mechanism: Reduces kidney urate clearance and raises deposition risk during therapy

→ Maintain tuberculosis course, check urate with joint symptoms, choose flare treatment that spares liver where possible

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Epidemiology

Prevalence:Gout is common in adults and rises with age and hyperuricaemia (high blood urate). It is seen regularly in primary care and emergency settings. Burden is higher where obesity (excess weight) with kidney disease and diuretic (water tablet) use are common. Flares often recur without urate-lowering strategy.

Age Group:Gout mainly affects middle-aged and older men. Male predominance holds from early adulthood through middle age. Risk rises in postmenopausal women (women after periods stop) as oestrogen (female hormone) protection falls. Young onset suggests kidney, genetic or drug cause. Children are rarely affected except in rare metabolic disease.

Sex Predilection:Male

Geographic Distribution:Gout occurs worldwide in all populations. Burden is higher where rich diet with longevity and vessel risks cluster. Prevalence rises where hypertension (high blood pressure) with kidney disease is common. No climate restriction applies.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 URGENT

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Septic arthritis (joint infection) that mimics gout and destroys joint rapidly
Fever with single hot joint needing same-day aspiration even with gout history
Kidney stones with obstruction and infection
Allopurinol hypersensitivity (severe drug reaction) with rash and organ injury

URGENT EVALUATION TRIGGERS

Fever with hot joint
Severe pain with inability to bear weight
First ever flare with uncertain diagnosis
Spreading redness with systemic illness (body-wide infection signs)
Flank pain with fever suggesting infected stone

Contraindications & Precautions

CONTRAINDICATIONS

Do not use aspirin for flare pain as low doses can raise urate
Do not start urate lowering during acute flare without flare cover
Do not label hot swollen joint as gout without excluding infection
Do not use systemic steroids (body-wide steroid tablets) without checking sugar and infection risk

SPECIAL PRECAUTIONS

Check kidney function with urate and pressure before drug choices
Screen for hypertension (high blood pressure) with diabetes (high blood sugar) and lipid disorder
Counsel on alcohol with sugary drinks and weight
Monitor for skin reaction when starting allopurinol (urate-lowering drug)
Ensure flare prophylaxis (preventive cover) when initiating urate lowering

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Tophi (firm urate lumps) with ulceration and joint deformity
Chronic joint damage with pain and reduced movement
Kidney stones (hard urine minerals) with colic and obstruction
Chronic kidney disease (long term kidney failure) from deposition
Delayed septic arthritis (joint infection) diagnosis from mimicry

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Pseudogout

Name overlaps with gout and both cause crystal arthritis but pseudogout involves calcium crystals (different deposits) not urate

Gouge injury

Sounds similar when spoken but means traumatic wound, not crystal arthritis

Goitre

Shares Go opening but means thyroid enlargement (neck swelling) not joint disease

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Septic arthritis

Key Distinguishing Feature: Fever with severe pain and positive fluid culture (germ test) needing urgent drainage, crystals do not exclude it

Pseudogout

Key Distinguishing Feature: Knee or wrist disease with weakly positive crystals (dim glow under polarised light) favouring calcium disease

Cellulitis

Key Distinguishing Feature: Spreading skin redness without joint crystals and with skin tenderness favouring skin infection

Reactive arthritis

Key Distinguishing Feature: Recent gut or genital infection with multi-joint pain and urethritis (urine tube inflammation)

Rheumatoid arthritis

Key Distinguishing Feature: Symmetric small-joint swelling with morning stiffness and positive antibodies, not abrupt monoarthritis

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Clinical Pearls

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Serum urate (blood urate test) can be normal during flare so repeat after settling and do not rule out gout on one normal result.

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Always aspirate (sample joint fluid) a hot joint when septic arthritis (joint infection) is possible even with known gout history.

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Ultrasound double contour (bright line over cartilage) supports gout but crystal proof remains the standard.

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Start flare prophylaxis (preventive cover with colchicine or anti-inflammatory) when initiating urate lowering to prevent early flares from crystal shifts.

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Check kidney function with pressure, sugar and lipids at diagnosis because control of vessels and weight improves gout outcomes.

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Example Usage & SOAP

CLINICAL SENTENCE

""52-year-old man with abrupt first-toe pain and swelling has acute gout.""

IN A SOAP NOTE

S: 52-year-old man with sudden left first-toe pain overnight rated severe, no fever or trauma, on thiazide (water tablet) for pressure. O: Temp 37.7C, BP 152/94, HR 94, RR 18, SpO2 98 percent on air, left first MTP (big toe joint) hot and swollen and tender, no skin break. A: Acute podagra likely gout flare with infection not yet excluded. P: Same-day joint aspiration with crystal analysis and culture, check urate with kidney function, start anti-inflammatory if safe, safety-net for fever with rheumatology follow up.

DIFFERENTIAL DIAGNOSIS CONTEXT

Abrupt first-toe monoarthritis (single hot joint) with high urate favours gout over pseudogout. Knee disease with weakly positive crystals favours pseudogout. Fever with positive culture favours septic arthritis even when crystals are present. Spreading skin redness without effusion (joint fluid) favours cellulitis. Recent gut or genital infection with multi-joint pain favours reactive arthritis.

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Classifications & Scoring

GRADING SYSTEM

ACR EULAR gout classification criteria

Points-based system using clinical with crystal and imaging features to classify gout and support diagnosis

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Prognosis

SHORT-TERM OUTCOME

Acute flares often settle within days with anti-inflammatory care. Pain can be severe and limit walking and hand use. Short term risk is misdiagnosis of septic arthritis (joint infection). Early aspiration (joint fluid sampling) with treatment improves comfort. Recurrence is likely without trigger control.

LONG-TERM PROGNOSIS

With sustained urate lowering, flares stop and tophi (firm urate lumps) can shrink. Without control, flares recur and joints erode. Kidney stones with chronic kidney disease (long term kidney failure) may progress. Weight, pressure and lipid control improves outcomes. Lifelong follow up is often needed.

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References & Coding

ICD-10 DIAGNOSTIC CODE

M10.9

LITERATURE CITATIONS & GUIDELINES

[1]WHO ICD-10 M10 Gout

[2]NICE guidance on gout

[3]American College of Rheumatology gout management guidance

[4]European Alliance of Associations for Rheumatology gout recommendations

[5]Harrison's Principles of Internal Medicine crystal arthritis

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.