AANP Family Nurse Practitioner (FNP) Certification ExamAssessmentHard
A 48-year-old male presents with acute onset of right great toe pain, swelling, and redness. He reports the pain is excruciating and started suddenly last night. He denies trauma. His medical history includes hypertension, for which he takes hydrochlorothiazide. On examination, the right great toe is exquisitely tender, warm, and erythematous with overlying shiny skin. What is the most appropriate initial diagnostic test?
- AX-ray of the foot
- BErythrocyte sedimentation rate (ESR)
- CJoint aspiration for synovial fluid analysis
- DSerum uric acid level
Show answer & explanationAnswer & explanation
Correct answer: C. Joint aspiration for synovial fluid analysis
The patient's presentation (acute onset, excruciating unilateral great toe pain, swelling, redness, history of diuretic use) is highly suggestive of acute gout. While serum uric acid is often elevated, it can be normal during an acute attack. Joint aspiration with synovial fluid analysis for urate crystals (negative birefringent crystals) is the gold standard for definitively diagnosing gout and ruling out septic arthritis, which can present similarly.
Why the other options are wrong
- A. An X-ray of the foot may show soft tissue swelling but is not diagnostic of acute gout and is primarily useful for chronic changes or ruling out fracture.
- B. ESR is a general inflammatory marker and would be elevated in many inflammatory conditions, including gout and septic arthritis, thus not specific enough for diagnosis.
- D. Serum uric acid can be normal during an acute gout attack and is not diagnostic of acute gout, only hyperuricemia.
Acute Gout Diagnosis
Diagnosis of acute gout requires definitive identification of monosodium urate crystals in synovial fluid via joint aspiration, especially to rule out septic arthritis.
- Classic presentation: acute monoarthritis, often great toe (podagra).
- Serum uric acid can be normal in acute attack.
- Joint aspiration is gold standard for definitive diagnosis.
Memory trick: One Joint Aches: Tap It, See Crystals!