A 50-year-old obese man comes to the emergency department with toe pain. He awoke this morning with sudden severe pain in his left great toe. He has never had this type of pain before and has had no trauma to the toe. The patient has a history of hypertension treated with hydrochlorothiazide. He also has osteoarthritis in his right knee that was treated with an intraarticular steroid injection 6 months ago. He smokes a pack of cigarettes and drinks 1 or 2 glasses of wine daily. His temperature is 36.7 C (98.1 F), blood pressure is 130/80 mm Hg, pulse is 88/min, and respirations are 12/min. The patient's left great toe is inflamed, with swelling and erythema at the metatarsophalangeal joint. There is pain with minimal range of motion. There are no skin rashes. The remainder of the examination is within normal limits.
Which of the following is the best next step in confirming the diagnosis?

Question

A 50-year-old obese man comes to the emergency department with toe pain.  He awoke this morning with sudden severe pain in his left great toe.  He has never had this type of pain before and has had no trauma to the toe.  The patient has a history of hypertension treated with hydrochlorothiazide.  He also has osteoarthritis in his right knee that was treated with an intraarticular steroid injection 6 months ago.  He smokes a pack of cigarettes and drinks 1 or 2 glasses of wine daily.  His temperature is 36.7 C (98.1 F), blood pressure is 130/80 mm Hg, pulse is 88/min, and respirations are 12/min.  The patient's left great toe is inflamed, with swelling and erythema at the metatarsophalangeal joint.  There is pain with minimal range of motion.  There are no skin rashes.  The remainder of the examination is within normal limits. 
Which of the following is the best next step in confirming the diagnosis?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c0b0_df6d_8f63_0910db27c0ec_MD0005_00 This patient's presentation suggests acute monoarticular gout, which is due to intraarticular deposition of monosodium urate (MSU) crystals. Risk factors for gout include volume depletion, certain medications (eg, diuretics), high-protein or high-fat diet, increased alcohol consumption, and recent surgery or trauma. Patients usually develop acute onset of severe joint pain with erythema, swelling, and limited range of motion. Although most cases (>80%) occur in the 1st toe or knee, gout can also occur in other joints (eg, ankle, wrist, finger, shoulder, olecranon bursa). Patients with chronic hyperuricemia may also develop tophi, nodular deposits of MSU crystals in soft tissues with associated inflammatory changes. tophi Even if it is highly suspected clinically, gout should be confirmed with arthrocentesis. The synovial fluid usually contains MSU crystals that are needle-shaped and negatively birefringent under polarizing light. In contrast, pseudogout has positively birefringent rhomboid-shaped crystals. Joint fluid analysis and culture can also rule out septic arthritis, which can coexist with acute gout. MSU crystals pseudogout In patients unable to have arthrocentesis, gout can be conditionally diagnosed with the classic clinical findings (eg, acute onset, 1st toe involvement, significantly elevated uric acid level, tophi). However, clinical features alone are not as sensitive or specific as synovial fluid analysis. Many patients can have a normal or even low uric acid during an acute gouty attack (Choice D). (Choice B) Erythrocyte sedimentation rate can be elevated in gout or other inflammatory conditions (eg, septic arthritis, osteomyelitis) but is not sensitive or specific for diagnosis. (Choices C and E) Radiologic imaging is typically done to exclude other etiologies of joint pain (eg, fracture, osteomyelitis). However, it is not as effective as synovial fluid analysis for diagnosing acute gouty arthritis and is not necessary in patients with typical clinical features. In chronic gout, imaging can detect subcortical cysts suggestive of tophi or erosions in patients with recurrent attacks. Educational objective: Arthrocentesis confirms acute gout by showing monosodium urate crystals that are negatively birefringent and needle-shaped under polarizing light. Serum uric acid does not accurately diagnose acute gout as many patients can have normal or even low uric acid during an acute gouty attack. References: Diagnosis and treatment of gout in primary care. (http://www.ncbi.nlm.nih.gov/pubmed/22272526) EULAR evidence based recommendations for gout. part I: diagnosis. report of a task force of the Standing Committee for International Clinical Studies Including Therapeutics (ESCISIT). (http://www.ncbi.nlm.nih.gov/pubmed/16707533) A diagnostic rule for acute gouty arthritis in primary care without joint fluid analysis. (http://www.ncbi.nlm.nih.gov/pubmed/20625017)

A 50-Year-Old Obese Man Comes to the Emergency Department with Toe