Gout Signs and Symptoms
Definition
- Gout is a condition wherein there is increased urate in the body, also called hyperuricemia, that leads to deposition of monosodium urate monohydrate crystals in various tissues (eg joints, connective tissue, kidney)
Epidemiology
- It is the most common inflammatory arthritis in men
- In US and Europe, the estimated prevalence of gout is 3% of the adult population
- Prevalence of gout in the Asia-Pacific region varies
- Ethnic groups in China and Malaysia (eg Malays, Tamils) were found to have higher uric levels as compared to the Japanese and Thai
- Taiwan is one of the countries in the world with the highest prevalence of gout
Pathophysiology
- Hyperuricemia is a necessary precondition for the development of monosodium urate monohydrate crystal deposition but this has to be distinguished from gout, the clinical syndrome
- Results in acute and chronic inflammation associated with changes in articular and periarticular structures
Causes of Hyperuricemia
- Excessive uric acid production
- Inherited enzyme defects (eg hypoxanthine-guanine phosphoribosyl transferase deficiency, phosphoribosyl pyrophosphate synthetase overactivity, glycogen storage diseases, fructose-1-phosphate aldolase deficiency, myoadenylate deaminase deficiency, carnitine palmitoyltransferase II deficiency)
- Clinical disorders (eg myeloproliferative and lymphoproliferative disorders, malignancies, psoriasis, Down syndrome)
- Induced by diet, drugs, or toxins (eg Ethanol, excessive purine in diet, fructose, vitamin B12 deficiency, Nicotinic acid, cytotoxic drugs, Warfarin)
- Decreased renal clearance
- Genetic disorders such as medullary cystic kidney disease, familial juvenile hyperuricemic nephropathy and uric acid transportasome mutations
- Chronic renal insufficiency, volume depletion (eg heart failure, volume loss), obesity, diabetic or starvation ketoacidosis, lactic acidosis, hyperparathyroidism, hypothyroidism, sarcoidosis
- Induced by diet or drugs (eg Aspirin, diuretics, Ciclosporin, Tacrolimus, Ethambutol, Pyrazinamide, Ethanol, Levodopa)
- Saturnine gout is a rare form of gout due to chronic lead exposure
- Commonly seen in plumbers and those exposed to lead-based paints
Clinical Phases of Gout
Acute Gout
- Usually manifests as an acute, self-limiting, monoarticular inflammatory arthritis in majority of patients
- Symptoms of a gout flare include severe pain, redness, swelling, warmth and disability
- Lower extremity joints are affected more often than upper extremity joints
- Joints most commonly affected include the 1st metatarsophalangeal joint (podagra), forefoot, ankle, knee
- Extra-articular sites (eg olecranon bursa and Achilles tendon) may also be involved
- Attacks may occur and last from a few days to 2-3 weeks, with resolution of all inflammatory signs
- Early attack: <12 hours after onset of attack
- Well-established attack: 12-36 hours after onset of attack
- Late attack: >36 hours after attack onset
Intercritical Gout
- Periods in between attacks when patient is free of symptoms
- Asymptomatic joints may still have crystals detected in the synovial fluid
Chronic Gout
- If hyperuricemia is not treated properly, intermittent acute gouty attack can develop into chronic gouty arthritis
- There is persistent inflammation in the joints and connective tissues associated with bony erosions and deformities
- Chronic tophaceous gout:
- Marked by polyarticular arthritis and the formation of tophi which are chalky deposits of monosodium urate
- Tophi are usually painless, appearing as firm, nodular or fusiform masses located subcutaneously
- Risk factors include polyarticular presentation, serum urate level 9 mg/dL (>0.54 mmol/L)
- Presence of urate nephropathy or urate renal calculi
Risk Factors
- Risk factors for gout and associated comorbidity should be assessed
Risk Factors Associated with Gout
- Hyperuricemia
- Single most important risk factor for developing gout
- Male sex
- Menopausal women
- Age
- Purine-rich diet (eg meat, seafood)
- Alcohol intake
- Drug use (eg diuretics, low-dose Aspirin, Ciclosporin)
- Lead exposure
- Obesity
- Renal insufficiency
Metabolic Abnormalities/Comorbidities Associated with Gout
- Hypertension
- Obesity
- Dyslipidemia
- Hyperglycemia and insulin resistance
- Coronary artery disease
- Type 2 diabetes mellitus
- Renal insufficiency
- Metabolic syndrome
- Kidney stone