A 54-year-old man is hospitalized due to progressive dyspnea on exertion and orthopnea. Evaluation reveals jugular venous distension, bibasilar crackles, and pitting edema of the bilateral lower extremities. Echocardiography shows decreased left ventricular contractility with an ejection fraction of 30%. Coronary angiography reveals no obstructive coronary artery disease. Symptoms gradually improve with intravenous furosemide. On the fourth day of hospitalization, the patient begins to experience severe right foot and ankle pain. The pain started suddenly during the night with no antecedent trauma. He had an episode of right knee pain several years ago, which improved with over-the-counter analgesics. The patient has a history of hypertension and HIV. CD4⁺ cell count was 450/mm³ 2 months ago. Antiretroviral therapy has been continued since admission.
Temperature is 38 C (100.4 F) . Examination shows redness, warmth, tenderness, and decreased range of motion in the right ankle and midfoot. There is no skin rash.
Leukocyte count is 13,200 cells/mm³ and serum creatinine is 1.0 mg/dL. Radiography of the right foot and ankle shows no fracture or dislocation, but significant soft tissue swelling and a heel spur are seen.
Which of the following is most likely contributing to this patient's foot pain?

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11ec193a_9727_d407_853d_e19537913659_MD0002_00 This patient was initially admitted for decompensated heart failure (ie, dyspnea, orthopnea, edema, lung crackles, decreased ventricular function) and responded to appropriate treatment. He then developed acute ankle monoarthritis consistent with gout. Acute gout is common in hospitalized patients and can be triggered by infection, surgery, trauma, dehydration, medications, and impaired renal function. The diagnosis can be confirmed by synovial fluid analysis showing needle-shaped, negatively birefringent uric acid crystals. Loop diuretics are common triggers of gout in hospitalized patients. Diuretics can increase serum urate levels through both volume depletion and increased urate reabsorption in the proximal tubule. Thiazide diuretics also raise uric acid levels by acting as a counter-transporter for urate and are relatively contraindicated in patients with gout. Because nonsteroidal anti-inflammatory drugs should generally be avoided in patients with decompensated heart failure, alternate treatment options include systemic or intra-articular glucocorticoids. (Choice A) HIV can exacerbate a variety of arthritic syndromes (eg, rheumatoid arthritis, spondyloarthropathy), but antiretroviral therapy commonly reduces symptoms. Initiation of antiretroviral therapy can occasionally trigger acute gout due to an immune reconstitution syndrome, but chronic therapy would have little effect. (Choice B) Cholesterol emboli can occur after cardiac catheterization or other vascular procedures (eg, arteriography, vascular surgery) in patients with extensive atherosclerosis. They typically cause systemic symptoms, livedo reticularis with mottled skin, distal cyanosis, and acute kidney injury. Acute monoarthritis is not a common manifestation. (Choice D) Heel spurs (calcification of the plantar fascia) can be a sign of chronic plantar fasciitis but are also a common finding in asymptomatic patients. They rarely cause symptoms directly. (Choice E) Compression of the tibial nerve at the tarsal tunnel causes sensory loss over the sole with intrinsic foot muscle weakness (tarsal tunnel syndrome). Common causes include ankle fracture or dislocation involving the talus, calcaneus, or medial malleolus; scar tissue; bony spurs; bone/cartilage fragments; malignancy; and inflammatory conditions (eg, rheumatoid arthritis). Educational objective: Acute gout is common in hospitalized patients and can be triggered by infection, surgery, trauma, dehydration, medications, and impaired renal function. Loop diuretics can cause acutely elevated serum uric acid levels and trigger a flare of gout. __________ References: Use of diuretics and risk of incident gout: a population-based case-control study. (http://www.ncbi.nlm.nih.gov/pubmed/24449584)

A 54-Year-Old Man Is Hospitalized Due to Progressive Dyspnea on Exertion