A 57-Year-Old Man Comes to the Emergency Department Due to a 1-Day

question 100

Multiple Choice

A 57-year-old man comes to the emergency department due to a 1-day history of pain and swelling in his right knee.  The pain is severe, and he has had difficulty bearing weight on the right leg.  He previously felt well.  Past medical history is notable for hypertension and seasonal allergies.  The patient does not use tobacco and drinks 1 or 2 alcoholic beverages a week.  On examination, the right knee is red and swollen.  He has pain with passive range of motion at the knee.  The knee ligaments show no significant laxity.  Synovial fluid obtained from the involved joint shows a white blood cell count of 25,000/mm³, with a neutrophilic predominance, and numerous crystals (shown below) . These crystals are most likely composed of which of the following substances?

• A)Calcium hydroxyapatite
• B)Calcium oxalate
• C)Calcium pyrophosphate
• D)Cholesterol
• E)Monosodium urate
• F)Uric acid

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Definitions:

Urinary

Related to the system in the human body that produces, stores, and expels urine.

Circulatory

Pertaining to the system that circulates blood and lymph through the body, comprising the heart, blood vessels, and lymphatic vessels.

Immune

Relating to or denoting the body's system of defense mechanisms against pathogens, including the production of antibodies and the activation of white blood cells.

Adipose Cells

Cells specialized in storing fat, providing insulation and energy reserves for the body.