31st January 2024

Presentation

Crystal arthropathy usually causes monoarthropathy. Typical joints involved in gout are the first metatarsophalangeal joint, ankle, knee, fingers, wrist, and elbow. If up to 4 joints are affected, this is oligoarthropathy, and it is polyarthropathy when more than 5 joints are affected.

Signs and Symptoms

Patients usually present with sudden onset pain. The associated signs on examination include erythema, swelling, tenderness and warmth of the affected joint. Generally, the patient would be otherwise systemically well. The pain is severe and often affects activities of daily living- this can be demonstrated by asking the patient to perform certain tasks (please see the examination section below). The acute joint pain can be associated with mild fever and rise in inflammatory markers, so it is essential to rule out septic arthritis; in septic arthritis, the patient would be acutely unwell.

Articular vs Extra-articular Manifestations

Extra-articular manifestations of gout present as gouty tophi. These are subcutaneous concentrations of urate crystals. These appear as white deposits of a chalk-like substance beneath the skin. Tophi can occur without previously having an acute attack of gout and do not typically cause pain. Common sites for tophaceous deposits include:

• The pinna of the ear. 
• The Achilles tendon
• The pulp of the fingers
• The olecranon bursa. This can give the appearance of rheumatoid nodules, so careful history and examination of the patient are needed.

Another extra-articular feature of gout are renal calculi. These form due to uric acid salt deposition within the renal matrix. Low urinary pH increases the risk of uric acid stones and nephrolithiasis. Stone formation is an important cause of renal failure and should be considered and the risk reduced. 

Complications of Hyperuricaemia

In addition to renal impairment, studies have shown that uric acid levels are independent risk factors for cardiovascular disease and associated mortality, particularly in those with hypertension and diabetes mellitus. This is related to oxidative stress caused by raised urate levels and inflammatory changes in the vasculature and is supported by urate-lowering therapies, such as allopurinol, resulting in improved cardiovascular outcomes.

The inflammatory process, when triggered within blood vessels, causes damage to the endothelium. Attempts to repair the damage results in fatty plaque deposits within the blood vessels, causing atheroma formation. This contributes to hypertension, which in turn increases blood vessel damage. Studies have shown that individuals with obesity but without metabolic syndrome have increased risk of diabetes and hypertension with raised serum urate levels. This is also true of lean individuals. 

Image Source: Wikimedia Commons (2014). Tophaceous gout, Licensed under a creative commons licence. Available for free at:  https://commons.wikimedia.org/wiki/File:Tophaceous_gout.jpg (Accessed: 30 April 2022).

Pseudogout often has a more insidious course, and symptoms may take longer to reach maximum debilitation during each flare, and there is often a longer recovery period. It is not uncommon for larger joints to be affected by pseudogout, such as knees. 

References 

• Harris MD, Siegel LB, Alloway JA. Gout and Hyperuricemia. American Family Physician [Internet]. 1999 Feb 15 [cited 2022 May 9];59(4):925. Available from: https://www.aafp.org/afp/1999/0215/p925.html#:~:text=Gout%20progresses%20through%20four%20clinical
• Society PCD. Gouty tophi [Internet]. Primary Care Dermatology Society. [cited 2022 Apr 30]. Available from: https://www.pcds.org.uk/clinical-guidance/gouty-tophi
• e.roddy@cphc.keele.ac.uk ARUPCC Primary Care Sciences, Keele University, Keele, UK. English:  Tophaceous gout affecting the right great toe and finger interphalangeal joints. Note the asymmetrical swelling and yellow-white discolouration. [Internet]. Wikimedia Commons. 2014 [cited 2022 Apr 30]. Available from: https://commons.wikimedia.org/wiki/File:Tophaceous_gout.jpg
• MacMullan P, McCarthy G. Treatment and management of pseudogout: insights for the clinician. Therapeutic Advances in Musculoskeletal Disease. 2011 Dec 21;4(2):121–31.
• Arthritis Foundation. Juvenile Idiopathic Arthritis [Internet]. Arthritis.org. 2020 [cited 2022 Feb 5]. Available from: https://www.arthritis.org/diseases/juvenile-idiopathic-arthritis
•  Lillicrap M. Crystal arthritis: contemporary approaches to diseases of antiquity. Clinical Medicine. 2007 Jan 1;7(1):60–4.
• Gupta MK, Singh JA. Cardiovascular Disease in Gout and the Protective Effect of Treatments Including Urate-Lowering Therapy. Drugs. 2019 Mar 13;79(5):531–41.
• Kuwabara M, Kuwabara R, Hisatome I, Niwa K, Roncal-Jimenez CA, Bjornstad P, et al. “Metabolically Healthy” Obesity and Hyperuricemia Increase Risk for Hypertension and Diabetes: 5-year Japanese Cohort Study. Obesity. 2017 Sep 18;25(11):1997–2008.