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

---

Definitions:

Garcia And Garcia y Robertson

Refers to John Garcia and his research, often with collaborators, on conditioned taste aversions, illustrating how some associations are easier to learn due to evolutionary predispositions.

Learning

The process of acquiring new understanding, knowledge, behaviors, skills, values, attitudes, or preferences through experience, study, or teaching.

Instinctive Drift

The tendency of an animal to revert to instinctive behaviors that interfere with a conditioned response.

Pigs

Domesticated or wild animals belonging to the genus Sus, known for their intelligence and social behavior.