Acute Gout in Adults

Name: Acute Gout in Adults
Creator: MedVellum Editorial Team

1. Clinical Overview

Summary

Acute gout is an intensely painful, inflammatory monoarthritis caused by the deposition of monosodium urate (MSU) crystals within joints and soft tissues. [1] It is the most common form of inflammatory arthritis in men, strongly associated with hyperuricaemia and the metabolic syndrome. [2]

Management has shifted towards a "Treat-to-Target" strategy, pioneered by the British Society for Rheumatology (BSR, 2017) and the American College of Rheumatology (ACR, 2020). [3,4] While acute flares are managed with NSAIDs, colchicine, or steroids, long-term prevention via urate-lowering therapy (ULT), primarily Allopurinol, is essential to prevent tophi, joint destruction, and renal complications. [5] Notably, the 2020 ACR guidelines suggest that Allopurinol may be started during an acute flare, provided it is at a low dose and covered by anti-inflammatory prophylaxis. [4]

Key Facts

Podagra: The 1st metatarsophalangeal (MTP) joint is affected in > 70% of first attacks. [1]
The Urate Paradox: Serum urate levels can be normal or low during an acute attack (due to the acute phase response). Do not use a single normal urate result to rule out gout. [6]
Gold Standard: Polarised light microscopy of synovial fluid showing negatively birefringent needle-shaped crystals. [7]
Treat-to-Target: Aim for serum urate less than 360 µmol/L (6 mg/dL) for most, or less than 300 µmol/L (5 mg/dL) in patients with tophi or severe disease. [3,4]
SGLT2 Inhibitors: Medications like Empagliflozin have a secondary uricosuric effect and reduce gout flares in diabetic patients. [8]

Clinical Pearls

The "Septic Gout" Pearl: Gout and Septic Arthritis can coexist. If a patient with known gout has a fever or is systemically unwell, you MUST aspirate to exclude infection, even if crystals are seen. [9]

The Ticagrelor Risk: Patients on Ticagrelor (but not Clopidogrel) have a significantly higher risk of hyperuricaemia and gout. If a patient develops gout after an ACS event, consider if Ticagrelor is the driver. [24,25]

Losartan for HTN: In hypertensive patients with gout, Losartan is the preferred ARB as it has unique uricosuric properties, whereas Thiazides and Loops increase urate. [11]

2. Epidemiology & Risk Factors

Incidence & Distribution

Prevalence: Affects ~2.5% of the UK population and ~3.9% in the US. [2]
Gender: Significantly more common in men (4:1 ratio); incidence in women increases post-menopause due to the loss of oestrogen's uricosuric effect. [12]
Ethnicity: Higher prevalence in Pacific Island populations (Maori and Polynesian) due to genetic variants in urate transporters (e.g., SLC2A9). [13]

Risk Factors

Category	Factor	Impact
Dietary	Purines/Fructose	Red meat, seafood, and high-fructose corn syrup increase urate production. [14]
Alcohol	Beer/Spirits	Beer is high in guanosine and reduces renal excretion. [1]
Medical	CKD	Reduced renal clearance is the most common cause of hyperuricaemia. [3]
Drugs	Diuretics/Ticagrelor	Thiazides and Ticagrelor increase urate levels significantly. [11,24]
Metabolic	Obesity	Increases urate production and reduces insulin sensitivity (reducing excretion).

3. Pathophysiology

1. The Urate Balance

Urate is the end-product of purine metabolism. Humans lack the enzyme uricase. Hyperuricaemia occurs via:

Under-excretion (90%): Reduced renal clearance via the URAT1/GLUT9 transporters. [15]
Over-production (10%): High purine intake or cell turnover (e.g., Lymphoma).

2. Crystal Deposition

When serum urate exceeds saturation (~380 µmol/L at 37°C), MSU crystals precipitate. They favour cooler peripheral joints (MTP) where solubility is lower. [1]

3. The NLRP3 Inflammasome

MSU crystals act as a "danger signal." They are phagocytosed by macrophages, triggering the NLRP3 inflammasome. This leads to the activation of caspase-1 and the massive release of IL-1β, which recruits neutrophils to the joint. [16]

4. Clinical Presentation

Symptoms

Abrupt Onset: Reaching peak intensity within 6–12 hours.
Exquisite Pain: Often described as "unbearable even to the touch of a bedsheet."
Erythema: Intense redness that can track into the soft tissues (mimicking cellulitis). [1]

Physical Signs

Tophi: Hard, chalky deposits (ear helix, olecranon bursa, Achilles). [17]
Podagra: Inflammation of the 1st MTP joint.
Desquamation: Skin peeling over the affected joint as the flare resolves.

5. Differential Diagnosis

Condition	Distinguishing Features	Diagnostic Clue
Septic Arthritis	Fever, systemic upset, lower pain threshold.	Joint Aspiration (Gram stain/culture).
Pseudogout (CPPD)	Older age, larger joints (Knee/Wrist).	Rhomboid, positively birefringent crystals.
Cellulitis	No joint line tenderness; spreading redness.	Normal joint aspiration; elevated WBC.
RA (Acute)	Symmetrical, smaller joints; prolonged stiffness.	RF/anti-CCP positive.

6. Investigations

1. Synovial Fluid Analysis (Gold Standard)

Microscopy: Needle-shaped, negatively birefringent crystals.
Cell Count: Inflammatory (20,000–100,000 cells/mm³).
Culture: Mandatory to exclude sepsis. [7,9]

2. Blood Tests

Serum Urate: Baseline for ULT; may be low during a flare. Repeat in 2–4 weeks. [6]
CRP/ESR: Markedly elevated.
Renal Function: Essential before prescribing NSAIDs or Allopurinol.

3. Imaging

Ultrasound: The "Double Contour" sign (hyperechoic band on hyaline cartilage). [19]
X-ray: "Punched-out" erosions with overhanging edges (late stage). [18]
Dual-Energy CT (DECT): Can detect and quantify the total body urate burden; useful in atypical presentations. [20,26]

7. Management Algorithm

                  [ACUTE HOT, SWOLLEN JOINT]
                             |
              +--------------v--------------+
              |   ASPIRATE JOINT (IF FEVER) |
              |   Rule out Septic Arthritis |
              +--------------+--------------+
                             |
              /--------------+--------------\
      [CRYSTALS SEEN]                [NO CRYSTALS SEEN]
             |                        |
      +------v------+          +------v------+
      | ACUTE GOUT  |          | CONSIDER DX |
      +------v------+          | (Septic,    |
             |                 | Pseudogout) |
      /------+------\          +-------------+
 [NO CONTRA-IND]  [CONTRA-IND]
       |          (Renal/GI/HF)
+------v------+   +------v------+
| 1. NSAIDs   |   | 1. STEROIDS |
|    (Naproxen)|   | (Oral/IA)   |
| 2. COLCHICINE|   | 2. IL-1 INH |
+------v------+   +------v------+
             |
      +------v------+
      | START ULT?  | < --- ACR 2020: Can start Allopurinol
      | (Allopurinol)|      DURING the flare (if covered).
      +------v------+
             |
      +------v------+
      | TITRATE     | < --- Increase 100mg q2-4wks
      | TO TARGET   |      Target less than 360 umol/L.
      +-------------+

8. Management

1. Acute Flare Treatment

NSAIDs: Naproxen 500mg BD or Ibuprofen 400mg TDS. [3]
Colchicine: 500mcg BD-TDS. Low-dose is as effective as high-dose with fewer side effects (AGREE Trial). [21]
Corticosteroids: Prednisolone 30mg OD for 5 days or Intra-articular (if sepsis ruled out). [4]

2. Urate-Lowering Therapy (ULT)

Indication: ≥2 flares/yr, Tophi, CKD stage 3+, or Urolithiasis. [4]
Allopurinol (First-line): Start at 100mg OD (lower in CKD).
The "Flare Cover": Co-prescribe low-dose colchicine (500mcg OD) for 3–6 months when starting ULT to prevent "mobilisation flares." [10]
Starting during a flare: 2020 ACR guidelines state Allopurinol may be started during the acute flare to improve long-term adherence. [4]

9. Evidence & Landmark Trials

ACR 2020 Guidelines (PMID: 32390306): Conditional recommendation to start ULT during an acute flare rather than waiting. [4]
BSR 2017 Guidelines (PMID: 28549089): Established the treat-to-target level of less than 360 µmol/L. [3]
AGREE Trial (PMID: 20186634): Proved low-dose colchicine efficacy. [21]
CARES & FAST Trials (PMID: 29527974, 33171442): Debated the CV safety of Febuxostat vs Allopurinol. [22,23]
PEAK Study: Identified SGLT2 inhibitors as beneficial for reducing urate in diabetic patients. [8]

10. Single Best Answer (SBA) Questions

Question 1

A 54-year-old male with a history of hypertension and recent ACS presents with a red, hot 1st MTP joint. He was recently started on Ticagrelor. His serum urate is 340 µmol/L (Normal). What is the next best step?

A) Start Antibiotics for cellulitis
B) Aspirate the joint to confirm crystals
C) Discontinue Ticagrelor immediately
D) Reassure him it cannot be gout as urate is normal
E) Start Allopurinol 300mg immediately
Answer: B. Aspiration is the gold standard. Urate can be normal during a flare. Ticagrelor is a risk factor but diagnosis must be confirmed first.

Question 2

According to the 2020 ACR guidelines, when is the most appropriate time to initiate Allopurinol in a patient with recurrent flares?

A) Exactly 4 weeks after the flare has resolved
B) Only after two normal urate readings
C) During the acute flare, with anti-inflammatory cover
D) Only if the CRP is less than 5
E) After 6 months of dietary modification
Answer: C. ACR 2020 supports starting during the flare to improve adherence.

Question 3

What is the target serum urate level for a patient with multiple gouty tophi?

A) less than 420 µmol/L
B) less than 360 µmol/L
C) less than 300 µmol/L
D) less than 200 µmol/L
E) Just below the laboratory reference range
Answer: C. Tophaceous disease requires a lower target (less than 300) to promote crystal dissolution.

Question 4

Which of the following describes the crystal findings in Gout?

A) Rhomboid, positively birefringent
B) Needle-shaped, negatively birefringent
C) Needle-shaped, positively birefringent
D) Envelope-shaped, non-birefringent
E) Rhomboid, negatively birefringent
Answer: B. MSU crystals are needle-shaped and negatively birefringent.

Question 5

A patient with Type 2 Diabetes and Gout needs an add-on glucose-lowering agent. Which would provide a secondary benefit for his gout?

A) Gliclazide
B) Metformin
C) Empagliflozin
D) Sitagliptin
E) Pioglitazone
Answer: C. SGLT2 inhibitors like Empagliflozin have uricosuric effects.

Question 6

Which imaging sign is pathognomonic for gout on ultrasound?

A) Apple-core sign
B) Double contour sign
C) Sail sign
D) Fat pad sign
E) Bamboo spine
Answer: B. The double contour sign represents urate crystals on the cartilage surface.

Question 7

A 40-year-old on Allopurinol 100mg has a urate of 400 µmol/L. He had one flare last month. What is the next step?

A) Add Febuxostat
B) Increase Allopurinol to 200mg
C) Switch to Probenecid
D) Stop Allopurinol
E) Add daily Naproxen indefinitely
Answer: B. ULT should be titrated (Treat-to-Target) until urate is less than 360.

Question 8

Which mechanism explains why beer is more likely to cause gout than spirits?

A) Ethanol content only
B) Presence of purine (guanosine)
C) Dehydration
D) Liver toxicity
E) Interaction with Vitamin C
Answer: B. Beer contains guanosine, which is metabolised to urate.

Question 9

What is the role of the NLRP3 inflammasome in gout?

A) It breaks down urate crystals
B) It prevents neutrophil recruitment
C) It processes Pro-IL-1β into active IL-1β
D) It increases renal urate excretion
E) It is the target of Allopurinol
Answer: C. NLRP3 activation by crystals drives the inflammatory cascade via IL-1β.

Question 10

Which medication should be co-prescribed for 3-6 months when starting Allopurinol?

A) Prednisolone 30mg
B) Colchicine 500mcg OD
C) Omeprazole
D) Vitamin D
E) Low-dose Aspirin
Answer: B. Prophylaxis prevents mobilisation flares during ULT initiation.

11. Patient Explanation

"Gout is a type of arthritis caused by small, needle-like crystals forming inside your joints. These crystals are made of a waste product called uric acid. Normally, your kidneys flush uric acid away, but if levels get too high, it can 'salt out' in your joints—often the big toe.

Think of a gout attack like a 'chemical fire.' The pain is intense because your immune system attacks the crystals as if they were a dangerous infection. While we use short-term medicines to put out the fire, the most important part is the long-term plan. We use a tablet called Allopurinol to lower the uric acid levels so crystals can't form. This medicine is usually for life—if you stop it, the crystals will eventually come back. You can also help by staying hydrated and limiting beer and red meat."

12. References

Dalbeth N, et al. Gout. Lancet. 2016;388(10055):2039-2052. [PMID: 27112094]
Kuo CF, et al. Global epidemiology of gout. Nat Rev Rheumatol. 2015;11(12):685-95. [PMID: 26150127]
Hui M, et al. British Society for Rheumatology Guideline for the Management of Gout. Rheumatology. 2017;56(7):e1-e20. [PMID: 28549089]
FitzGerald JD, et al. 2020 American College of Rheumatology Guideline for the Management of Gout. Arthritis Care Res. 2020;72(6):744-760. [PMID: 32390306]
Stamp LK, et al. Gout. Lancet. 2021;397(10287):1843-1855. [PMID: 33776608]
Schlesinger N, et al. Serum urate during acute gout. J Rheumatol. 2009;36(6):1287-9. [PMID: 19447937]
Pascual E, et al. Synovial fluid analysis. Best Pract Res Clin Rheumatol. 2005;19(3):395-410. [PMID: 15850931]
Fralick M, et al. SGLT2 Inhibitors and the Risk of Gout. Ann Intern Med. 2020;172(3):186-194. [PMID: 31931518]
Shah K, et al. When gout and septic arthritis coexist. Cleve Clin J Med. 2007;74(12):921-4. [PMID: 18154247]
Borstad GC, et al. Colchicine for prophylaxis of acute flares when initiating allopurinol. J Rheumatol. 2004;31(12):2429-32. [PMID: 15468361]
Choi HK, et al. Antihypertensive drugs and risk of incident gout. BMJ. 2012;344:d8190. [PMID: 22240117]
Hak AE, et al. Menopause, postmenopausal hormone use and risk of incident gout. Ann Rheum Dis. 2010;69(7):1305-9. [PMID: 20498211]
Dalbeth N, et al. Genetic and environmental risk factors for gout. Rheumatology. 2021;60(10):4451-4462.
Choi HK, et al. Fructose-rich beverages and risk of gout in women. JAMA. 2010;304(20):2270-8. [PMID: 21062951]
Sorensen LB. Role of the intestinal tract in the elimination of uric acid. Arthritis Rheum. 1965;8:694-706.
Martinon F, et al. Gout-associated uric acid crystals activate the NALP3 inflammasome. Nature. 2006;440(7081):237-41. [PMID: 16407889]
Chhana A, et al. The mechanism of tophus formation. Nat Rev Rheumatol. 2015;11(2):116-25. [PMID: 25422003]
Martel W. The overhanging margin of bone: a roentgenographic manifestation of gout. Radiology. 1968;91(4):755-6. [PMID: 5675437]
Thiele RG, et al. The "double contour" sign in gouty arthritis. J Rheumatol. 2007;34(10):2113-5. [PMID: 17787050]
Nicolaou S, et al. Dual-energy CT: a promising new technique for the assessment of gout. AJR Am J Roentgenol. 2009;193(4):997-1001. [PMID: 19770335]
Terkeltaub RA, et al. High versus low dosing of oral colchicine for early acute gout flare (AGREE trial). Arthritis Rheum. 2010;62(4):1060-8. [PMID: 20186634]
White WB, et al. Cardiovascular Safety of Febuxostat or Allopurinol in Patients with Gout (CARES trial). N Engl J Med. 2018;378(13):1200-1210. [PMID: 29527974]
Mackenzie IS, et al. Long-term cardiovascular safety of febuxostat compared with allopurinol (FAST trial). Lancet. 2020;396(10264):1745-1757. [PMID: 33171442]
Bonaca MP, et al. Ticagrelor and Gout in the PEGASUS-TIMI 54 Trial. J Am Coll Cardiol. 2016;67(21):2561-2. [PMID: 27230053]
Zhang Z, et al. Risk of gout associated with ticagrelor: a meta-analysis. Front Pharmacol. 2021;12:656360.
Christiansen SN, et al. Dual-energy CT in gout. Ann Rheum Dis. 2020;79(7):981-987.

Last Updated: 2026-01-04 | MedVellum Editorial Team | Status: Gold Standard (V4)

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