Gout
A severely painful form of inflammatory arthritis caused by the buildup of uric acid crystals in joints, often starting in the big toe.
Emergency Management: Concomitant septic arthritis in a gouty joint; acute uric acid nephropathy causing anuric acute kidney injury (more common in tumor lysis syndrome).
Gout is a crystal-deposition arthropathy caused by chronic hyperuricemia, leading to the precipitation of monosodium urate (MSU) crystals in joints, bones, and soft tissues. This results in recurrent attacks of acute, intensely painful inflammatory arthritis, most commonly affecting the first metatarsophalangeal joint. Over time, it can cause chronic joint destruction and subcutaneous nodules called tophi.
Detailed Overview
Gout is the most common form of inflammatory arthritis in adult men. It results from a mismatch between uric acid production and excretion—primarily renal underexcretion (90% of cases). The disease has distinct phases: asymptomatic hyperuricemia, acute flares, intercritical gout (symptom-free periods), and chronic tophaceous gout. Cardiovascular comorbidities are highly prevalent in gout patients, making holistic metabolic management essential alongside urate-lowering therapy.
Epidemiology & Demographics
Prevalence is approximately 3.9% in US adults. Striking male predominance (3-4:1 compared to females). Postmenopausal females are at increased risk due to loss of the uricosuric effect of estrogen. Peak age of onset is 40-50 years in men and >60 in women.
Etiological Mechanism
Driven by hyperuricemia (serum urate > 6.8 mg/dL). Caused by underexcretion of uric acid by the kidneys (primary or secondary to chronic kidney disease, diuretics) or overproduction (purine-rich diet, alcohol, myeloproliferative disorders, tumor lysis syndrome). Genetic polymorphisms in urate transporters (e.g., SLC2A9, ABCG2) strongly influence susceptibility.
Primary Causes
Renal impairment, thiazide and loop diuretics (decrease urate excretion), high intake of purines (red meat, shellfish), high fructose corn syrup, and excessive alcohol consumption (especially beer).
When serum uric acid exceeds its physiologic saturation point (approx. 6.8 mg/dL at physiological pH and temperature), it precipitates as needle-shaped MSU crystals in avascular tissues (cartilage) and relatively colder peripheral joints. These crystals are phagocytosed by resident macrophages, triggering the NLR family pyrin domain containing 3 (NLRP3) inflammasome. This leads to the activation of caspase-1 and massive release of Interleukin-1β (IL-1β). IL-1β drives intense neutrophil influx, vasodilation, and erythema, manifesting as an acute gout flare. Chronic deposition forms foreign-body granulomas (tophi) causing bone erosions.
Diagnostic Criteria & Guidelines
Gold standard is synovial fluid analysis showing negatively birefringent, needle-shaped monosodium urate crystals under polarized light microscopy. Clinically diagnosed using the 2015 ACR/EULAR criteria (score ≥8 based on clinical, lab, and imaging features).
Acute Flare: Indomethacin 50 mg PO TID or Naproxen 500 mg BID until symptoms resolve. Alternative: Colchicine 1.2 mg PO stat, then 0.6 mg 1 hour later (if within 36 hours of onset). Systemic or intra-articular corticosteroids (e.g., Prednisone 30-40 mg daily for 5 days) if NSAIDs/Colchicine are contraindicated (e.g., CKD).
Second-Line & Adjunctive Therapy
Urate-Lowering Therapy (ULT - for chronic management): Allopurinol starting at 100 mg daily (50 mg in CKD stage 4+), titrated every 2-5 weeks up to 800 mg daily to achieve a target Serum Uric Acid < 6.0 mg/dL. Must use concomitant flare prophylaxis (Colchicine 0.6 mg daily) for the first 3-6 months of ULT.
Surgical & Procedural Management
Surgical excision of tophi is rarely indicated, usually reserved for intractable pain, nerve entrapment (e.g., carpal tunnel syndrome), or recurrent infection of tophi.
Patient Counseling & Advice
Emphasize that gout is a chronic, lifelong disease requiring continuous daily medication (ULT), even when pain-free, to dissolve existing crystals and prevent flares. Warn about the paradox that starting Allopurinol can initially trigger a flare.
Follow-Up & Monitoring Schedule
Check Serum Uric Acid every 2-4 weeks during ULT titration until target (<6.0 mg/dL) is reached, then monitor every 6 months. Monitor renal function and LFTs.
Preventive Strategies
Strict adherence to daily Allopurinol and lifestyle/dietary modifications. Switching antihypertensives from Thiazides to Losartan (which has mild uricosuric effects) if possible.
Excellent with compliance to ULT. Tophi can completely resolve, and flares can be eliminated. Poor prognosis is linked to cardiovascular comorbidities and severe medication non-adherence.