Approach

Gout is clinically suspected in patients with typical history and examination findings.

A clinical diagnosis can be made with a good degree of certainty in patients with a reliable history of recurrent acute monoarthritis of the first metatarsophalangeal joint (podagra).[53] Rapid onset of severe pain, redness or swelling of joints other than the first metatarsophalangeal (e.g., midfoot, ankle, knee, hand, wrist, elbow) may also indicate a diagnosis of gout.[53]

Arthrocentesis showing monosodium urate crystals confirms the diagnosis of gout.[54]​​

In the UK, the National Institute for Health and Care Excellence (NICE) recommends performing a serum urate level as the first investigation to confirm the clinical diagnosis in patients with signs and symptoms of gout.[53] NICE recommends that arthrocentesis (with microscopy of synovial fluid) should be considered when the diagnosis of gout remains uncertain or unconfirmed following measurement of serum urate level.[53]

Alternatively, diagnosis may be based upon fulfilment of ≥6 of the following criteria from the American College of Rheumatology (ACR):[55]

  • More than one attack of acute arthritis

  • Maximum inflammation developed within 1 day

  • Monoarthritis attack, redness observed over joints

  • First metatarsophalangeal joint painful or swollen

  • Unilateral first metatarsophalangeal joint attack

  • Unilateral tarsal joint attack

  • Tophus (confirmed or suspected)

  • Hyperuricaemia

  • Asymmetrical swelling within a joint on x-ray film

  • Subcortical cyst without erosions on x-ray film

  • Joint culture negative for organism during attack.

In 2015 the ACR published new classification criteria; however, these criteria are intended to identify people who may be eligible for entry into a clinical study and they are not intended to be used to diagnose gout.[56][57]

History

Gout is more common in men and rare in pre-menopausal women.[2][3][5][8][37] A history of previous attacks that are self-limiting (7-14 days) supports the diagnosis. Medications, dietary habits, and family history should be assessed.

The most common presentation is acute monoarticular arthritis characterised by sudden-onset severe pain and swelling.[53][58] Symptoms often develop overnight.[53]

The disease may be oligoarticular (<4 joints involved) or, to a lesser degree, polyarticular (e.g., in older people, where it may be associated with marked oedema and swelling of the hands and feet). The most commonly affected joints are the first metatarsophalangeal, tarsometatarsal, ankle, and knee joints, but almost any other joint may be affected.[58]

Physical examination

Involved joints are warm, red, and swollen.[53] Usually, there is considerable tenderness and limited range of movement due to pain.

All joints should be examined, as others may be affected in a more subtle fashion.

Hard subcutaneous nodules (tophi) over the extensor surface of the joint, especially over the elbows, knees, and Achilles tendons, may be present.[53][58] Tophi may also be evident over the dorsal aspects of hands and feet, and in the helix of the ears. [Figure caption and citation for the preceding image starts]: Chronic tophaceous gout showing nodules in periarticular structures and arthritisAdapted from BMJ Case Reports 2009 [doi:10.1136/bcr.03.2009.1668] Copyright © 2009 by the BMJ Group Ltd [Citation ends].com.bmj.content.model.Caption@29e02410[Figure caption and citation for the preceding image starts]: Chronic tophaceous gout showing nodules in the hands, elbows, legs, buttocks, and abdominal wall (arrows)Adapted from BMJ Case Reports 2009 [doi:10.1136/bcr.03.2009.1668] Copyright © 2009 by the BMJ Group Ltd [Citation ends].com.bmj.content.model.Caption@704c6072

Investigations

The following tests may be considered in people with symptoms typical of gout.

Arthrocentesis with synovial fluid analysis

  • Provides definitive diagnosis.[54]

  • The synovial fluid white blood cell count usually exceeds 2.0 x 10⁹/L (2000/mm³ or 2000/microlitre), and the cells are mostly polymorphonuclear neutrophils type. Monosodium urate crystals (intracellular and/or extracellular needle-shaped crystals strongly negative for birefringence under polarised light) confirm the diagnosis. Synovial fluid analysis should be considered in most patients, but the diagnosis can often be made clinically.

  • In the UK, NICE recommends that arthrocentesis (with microscopy of synovial fluid) should be considered when the diagnosis of gout remains uncertain or unconfirmed following measurement of serum urate level.[53]

Serum uric acid level

  • May be low, normal, or high during an acute gout attack. This test becomes more reliable when done at least 2 weeks after the attack resolves.[59]

  • In the UK, NICE recommends performing a serum urate level as the first investigation to confirm the clinical diagnosis in patients with signs and symptoms of gout. A serum urate level 360 micromol/L (6 mg/dL) or more confirms a diagnosis of gout. If the serum urate level is below 360 micromol/L (6 mg/dL) during a gout flare, and gout is suspected, the test should be repeated at least two weeks after the flare has settled.[53]

Ultrasound

  • Ultrasound is more sensitive than x-rays in detecting erosions, tophi, and the gout-specific double contour sign (linear urate deposits over hyaline cartilage). Ultrasound findings, including tophi and erosion beside a double contour sign, have a sensitivity of 65% and specificity approaching 90%.[60][61]

  • Ultrasound is recommended for patients in the UK if joint aspiration can't be performed, or if the diagnosis of gout is uncertain.[53]

Dual energy computed tomography (DECT)

  • Could be helpful in the diagnosis of gout when it is in question, or for patients with contraindications for, or who refuse to have joint aspiration.[53][62][63][64]

  • Evidence suggests that DECT is valid and reliable, more sensitive than radiographs and computed tomography, and at least comparable to ultrasound for the diagnosis of gout.[65][66][67]

  • One meta-analysis concluded that DECT has a high diagnostic accuracy in established gout, but low sensitivity for recent-onset gout.[64][68]

Radiography

  • Radiographs are of limited diagnostic utility.[52] In late/severe gout, radiographic changes may help to differentiate between chronic gout and other joint conditions.[69]

  • X-ray findings suggestive of gout include soft-tissue opacifications with densities between soft tissue and bone, articular and periarticular bone erosions, and osteophytes at the margins of opacifications or erosions.[70] The hands are an optimal place to look for gouty erosions.

Aspiration and injection of the knee animated demonstration
Aspiration and injection of the knee animated demonstration

How to aspirate synovial fluid from the knee and administer intra-articular medication using a medial approach.

Aspiration and injection of the shoulder animated demonstration
Aspiration and injection of the shoulder animated demonstration

How to aspirate synovial fluid from the shoulder and administer intra-articular medication. Video demonstrates a posterior approach to the glenohumeral joint and a lateral approach to the subacromial space.

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