A 58-year-old man comes to the urgent care clinic complaining of severe left knee pain tha… — USMLE Step 2 CK

A 58-year-old man comes to the urgent care clinic complaining of severe left knee pain that awoke him from sleep. He has a medical history of hypertension and heart failure with preserved ejection fraction, for which he takes lisinopril and hydrochlorothiazide. His temperature is $37.9^\circ\text{C}$ ( $100.2^\circ\text{F}$ ). Physical examination reveals a swollen, erythematous, and exquisitely tender left knee with limited range of motion. There are no other joint abnormalities. Laboratory testing reveals a serum uric acid level of $5.8 \text{ mg/dL}$ (reference: $4.0-8.5 \text{ mg/dL}$ ). A diagnostic arthrocentesis is performed; synovial fluid analysis shows a leukocyte count of $42,000/\text{mm}^3$ with $85\%$ neutrophils, and the presence of needle-shaped, negatively birefringent crystals. Gram stain reveals no organisms. Which of the following is the most appropriate next step in management?

Intra-articular injection of a glucocorticoidAnswer
B
Intravenous administration of vancomycin and ceftriaxone
C
Measurement of serum antinuclear antibody levels
D
Administration of intravenous furosemide
E
Postponement of gout-specific therapy until the serum uric acid level becomes elevated

Answer

Intra-articular injection of a glucocorticoid

The patient's presentation of acute, severe monoarticular joint pain with warmth, swelling, and erythema, combined with synovial fluid demonstrating needle-shaped, negatively birefringent crystals, is diagnostic of an acute gout flare. The acute attack was likely triggered by the recent initiation of a thiazide diuretic (hydrochlorothiazide), which decreases renal urate excretion. While NSAIDs and colchicine are typical first-line treatments for acute gout, this patient has a history of heart failure with preserved ejection fraction; NSAIDs can exacerbate heart failure by causing fluid retention and should generally be avoided in these patients. Intra-articular glucocorticoid injection is highly effective for monoarticular gout, provides rapid relief, and minimizes systemic side effects, making it the most appropriate next step in management.

Step-by-Step Solution

Analyze the patient's clinical presentation and synovial fluid results.

The patient has acute monoarthritis with needle-shaped, negatively birefringent crystals and a leukocyte count of

42,000/\text{mm}^3

, confirming acute gout.

Synovial fluid crystal analysis is the gold standard for diagnosing crystal arthropathies and differentiating them from septic arthritis.

Evaluate the patient's comorbidities and current medications.

The patient has heart failure with preserved ejection fraction and is taking hydrochlorothiazide, which likely precipitated the gout flare.

Comorbidities dictate the choice of therapy. NSAIDs are typically first-line for gout but are contraindicated or highly cautioned in heart failure due to the risk of fluid retention and acute decompensation.

Select the safest and most effective targeted therapy for the acute flare.

Intra-articular glucocorticoids are selected over systemic NSAIDs or systemic steroids.

Intra-articular injection provides localized, rapid anti-inflammatory effects while minimizing the systemic adverse effects associated with NSAIDs or systemic corticosteroids in a patient with heart failure.

Key Concept

The diagnosis of acute gout is confirmed by the presence of negatively birefringent monosodium urate crystals in the synovial fluid. Serum uric acid levels may be normal during an acute flare. Intra-articular glucocorticoids are the preferred treatment for acute monoarticular gout in patients with contraindications to NSAIDs, such as heart failure.

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