[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Gout [Conditions](https://durgical.com/en/conditions/) · [Systemic conditions](https://durgical.com/en/conditions/) # Gout Gout is arthritis caused by uric acid crystals building up in joints; it causes sudden, very painful attacks, classically in the big toe. Updated 2026-10-29 ## Structures involved Tap one to see what it is and open it in 3D. - [Big toe](https://durgical.com/en/anatomy/great-toe/) - [MTP ligaments and plantar plate](https://durgical.com/en/anatomy/collateral-metatarsophalangeal-ligaments/) - [Joint capsule](https://durgical.com/en/anatomy/articular-capsule-of-knee-joint/) - [First metatarsal](https://durgical.com/en/anatomy/first/) - [Toe joint capsules](https://durgical.com/en/anatomy/capsules-of-metatarsophalangeal-and-interphalangeal-joints-of-foot/) - [Prepatellar bursa](https://durgical.com/en/anatomy/subcutaneous-prepatellar-bursa/) - [Kidneys](https://durgical.com/en/anatomy/kidney/) - [Ureters](https://durgical.com/en/anatomy/ureter/) ## In biochemistry - [De novo purine synthesis: Step 1 · PRPP synthetase](https://durgical.com/en/biochemistry/pathways/de-novo-purine-synthesis/#paso-1) - [Purine degradation and salvage: Step 5 · Xanthine oxidase](https://durgical.com/en/biochemistry/pathways/purine-degradation-and-salvage/#paso-5) - [Glucose-6-phosphatase](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphatase/) - [Ribose 5-phosphate](https://durgical.com/en/biochemistry/molecules/ribose-5-phosphate/) - [Fructose](https://durgical.com/en/biochemistry/molecules/fructose/) - [PRPP synthetase](https://durgical.com/en/biochemistry/enzymes/prpp-synthetase/) - [Glutamine-PRPP amidotransferase](https://durgical.com/en/biochemistry/enzymes/glutamine-prpp-amidotransferase/) - [Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)](https://durgical.com/en/biochemistry/enzymes/hypoxanthine-guanine-phosphoribosyltransferase/) - [Xanthine oxidase](https://durgical.com/en/biochemistry/enzymes/xanthine-oxidase/) - [PRPP (phosphoribosyl pyrophosphate)](https://durgical.com/en/biochemistry/molecules/prpp/) - [Uric acid](https://durgical.com/en/biochemistry/molecules/uric-acid/) - [Drugs acting on nucleotide metabolism](https://durgical.com/en/biochemistry/topics/drugs-acting-on-nucleotide-metabolism/) - [Types of enzyme inhibition](https://durgical.com/en/biochemistry/topics/types-of-enzyme-inhibition/) ## In histology - [Synovial joints: capsule, synovial membrane and articular cartilage](https://durgical.com/en/histology/synovial-joints-capsule-synovial-membrane-and-articular-cartilage/) ## In the clinical exam - [Joint examination: inspection, palpation and range of motion](https://durgical.com/en/clinical-exam/joint-examination-inspection-palpation-and-range-of-motion/) ## In physiology - [Tubular secretion of organic acids and bases](https://durgical.com/en/physiology/tubular-secretion-of-organic-acids-and-bases/) ## Why it happens - [Mediators of inflammation: the table to know](https://durgical.com/en/general-pathology/mediators-of-inflammation-the-table-to-know/) - [When leukocytes injure tissue: proteases, oxidants and NETs](https://durgical.com/en/general-pathology/when-leukocytes-injure-tissue-proteases-oxidants-and-nets/) - [Other forms of cell death: necroptosis, pyroptosis, ferroptosis](https://durgical.com/en/general-pathology/other-forms-of-cell-death-necroptosis-pyroptosis-ferroptosis/) - [Inflammation: the cardinal signs and its five steps](https://durgical.com/en/general-pathology/inflammation-the-cardinal-signs-and-its-five-steps/) - [Arachidonic acid metabolites in inflammation, and the drugs that block them](https://durgical.com/en/general-pathology/arachidonic-acid-metabolites-in-inflammation-and-the-drugs-that-block-them/) - [Heavy metals: lead, mercury, arsenic and cadmium](https://durgical.com/en/general-pathology/heavy-metals-lead-mercury-arsenic-and-cadmium/) ## Show 1 more - [Diet, cancer and systemic disease](https://durgical.com/en/general-pathology/diet-cancer-and-systemic-disease/) ## What it is An inflammatory arthritis caused by monosodium urate crystals depositing in and around joints when uric acid stays high for a long time. It causes sudden, very painful flares, classically in the big toe, and can lead to tophi and kidney stones. ## Who gets it The most common inflammatory arthritis in adult men; in women it appears mostly after menopause. It is linked to obesity, metabolic syndrome, hypertension and kidney disease, which are rising in Latin America. ## Causes - Hyperuricaemia from reduced kidney excretion of uric acid (most cases) - Overproduction of urate: high cell turnover (myeloproliferative disorders, tumour lysis), rare enzyme defects - Diet rich in purines (red meat, organ meats, seafood), alcohol (especially beer) and fructose-sweetened drinks - Drugs: thiazide and loop diuretics, low-dose aspirin, cyclosporine ## Risk factors - Male sex and older age; women after menopause - Obesity and metabolic syndrome - Hypertension and chronic kidney disease - Alcohol and sugary drinks - Diuretic use - Family history ## Pathophysiology Above about 6.8 mg/dL urate exceeds its solubility and forms needle-shaped crystals, favoured by cooler, acidic or damaged joints such as the first metatarsophalangeal joint. Macrophages phagocytose crystals and activate the NLRP3 inflammasome, releasing IL-1β and recruiting neutrophils. Chronic deposits form tophi that erode bone. ## Classification - Asymptomatic hyperuricaemia (not gout) - Acute gout flare - Intercritical (symptom-free) periods - Chronic tophaceous gout ## Symptoms and signs - Sudden, severe joint pain that peaks within 24 hours, often starting at night - Podagra: red, hot, swollen first metatarsophalangeal joint (big toe) - Other joints: midfoot, ankle, knee, wrist, fingers, [olecranon bursa](https://durgical.com/en/anatomy/olecranon-bursa/) - Exquisite tenderness; even a bed sheet hurts - Fever possible in large or multiple flares - Tophi: firm, chalky nodules on the ear, fingers, elbows or [Achilles tendon](https://durgical.com/en/anatomy/calcaneal-tendon/) ## Red flags - Fever with a hot joint and no prior gout, or immunosuppression (septic arthritis must be excluded) - A first flare in a large joint such as the knee - Flank pain or haematuria (urate stones) - Rising creatinine (urate nephropathy, or kidney disease affecting treatment) ## Diagnosis **Clinical** A typical flare in the [big toe](https://durgical.com/en/anatomy/great-toe/) with a known high urate suggests gout, but crystal identification is the gold standard; a clinical rule may be used where aspiration is not possible. **Tests** Joint aspiration: needle-shaped, negatively birefringent urate crystals under polarised light, with Gram stain and culture to exclude infection. Serum urate can be normal during a flare and is best rechecked a few weeks later; [kidney](https://durgical.com/en/anatomy/kidney/) function, glucose and lipids. **Imaging** Ultrasound shows the double-contour sign and tophi; dual-energy CT detects urate deposits. X-rays in chronic gout show punched-out erosions with overhanging edges. ## Differential diagnosis - Septic arthritis - Calcium pyrophosphate deposition (pseudogout) - Cellulitis - Reactive or psoriatic arthritis - Rheumatoid arthritis (in chronic polyarticular gout) - Fracture or trauma ## Goal of treatment Relieve the flare quickly and, in recurrent or tophaceous gout, lower serum urate long term so crystals dissolve and flares, tophi and joint damage stop. ## Treatment **Acute** Flare: NSAIDs, colchicine or glucocorticoids (oral or intra-articular), started as early as possible and chosen according to kidney function and other illnesses; rest and ice. **Medical** Urate-lowering therapy (xanthine oxidase inhibitors first line; uricosurics or uricase agents in selected cases) for recurrent flares, tophi, urate stones or joint damage, aiming for a target urate. **Medical** Flare prophylaxis with low-intensity anti-inflammatory therapy during the first months of urate-lowering therapy. **Lifestyle** Weight loss, less alcohol and sugary drinks, fewer purine-rich foods, and review of diuretics where possible. **Follow-up** Serum urate checks to adjust urate-lowering therapy to target, and kidney function. ## Drugs for this condition - [Ibuprofen](https://durgical.com/en/pharmacology/ibuprofen/) - [Indometacin](https://durgical.com/en/pharmacology/indometacin/) - [Naproxen](https://durgical.com/en/pharmacology/naproxen/) - [Betamethasone](https://durgical.com/en/pharmacology/betamethasone/) - [Allopurinol](https://durgical.com/en/pharmacology/allopurinol/) - [Febuxostat](https://durgical.com/en/pharmacology/febuxostat/) - [Colchicine](https://durgical.com/en/pharmacology/colchicine/) - [Probenecid](https://durgical.com/en/pharmacology/probenecid/) - [Pegloticase](https://durgical.com/en/pharmacology/pegloticase/) ## Complications - Chronic tophaceous gout with joint destruction - Uric acid kidney stones - Chronic kidney disease (often both cause and effect) - Tophus ulceration or infection - Associated cardiovascular disease ## Prognosis Flares settle in days to two weeks with treatment. With urate kept at target, flares stop and tophi shrink over months to years; without it, flares become more frequent and polyarticular. ## Prevention - Healthy weight and limiting alcohol and fructose drinks - Urate-lowering therapy continued long term once indicated - Managing associated hypertension, diabetes and kidney disease ## Test yourself Think of the answer, then tap the question to see it. ## What do urate crystals look like under polarised light? Needle-shaped and strongly negatively birefringent (yellow when parallel to the compensator axis); pseudogout crystals are rhomboid and weakly positive. ## What is podagra? A gout flare in the first metatarsophalangeal joint of the big toe: sudden pain, redness, heat and swelling; it is the classic first presentation. ## Why can serum uric acid be normal during a gout flare? Inflammation increases urate excretion, so levels may fall during a flare; a normal value does not exclude gout and is rechecked later. ## What is the main difference between flare treatment and urate-lowering therapy? Flare treatment (NSAIDs, colchicine, steroids) controls inflammation; urate-lowering therapy (for example xanthine oxidase inhibitors) dissolves crystals and prevents future flares. ## What are tophi? Collections of urate crystals surrounded by inflammatory tissue, felt as firm nodules (ear, fingers, elbow); they mark chronic, poorly controlled gout. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/gout/) ## Related conditions - [Gout of the Knee](https://durgical.com/en/conditions/gout-of-the-knee/) - [Pseudogout (CPPD) of the Knee](https://durgical.com/en/conditions/pseudogout-of-the-knee/) - [Septic Arthritis of the Knee](https://durgical.com/en/conditions/septic-arthritis-of-the-knee/) - [Rheumatoid arthritis](https://durgical.com/en/conditions/rheumatoid-arthritis/) - [Diabetic foot](https://durgical.com/en/conditions/diabetic-foot/) - [Cellulitis of the leg](https://durgical.com/en/conditions/cellulitis-of-the-leg/) - [Hallux valgus (bunion)](https://durgical.com/en/conditions/hallux-valgus/) - [Olecranon bursitis](https://durgical.com/en/conditions/olecranon-bursitis/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Gout](https://www.ncbi.nlm.nih.gov/books/NBK546606/) (StatPearls (NCBI Bookshelf), 2026). 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