Review Question - QID 214228

A 65-year-old woman with a history of osteopenia, hypertension, and hypothyroidism presents to the emergency department for severe arm pain for the past 4 hours. She reports that she felt a sudden pain at the left forearm shortly after lifting some heavy shopping bags at the mall. Acetaminophen did not alleviate the pain, and it has since progressed to 10/10 in severity. Her medical history is also significant for 2 episodes of community-acquired pneumonia within the past 4 months. The patient takes levothyroxine, lisinopril, hydrochlorothiazide, calcium, and vitamin D supplements. Radiograph of the left arm reveals a non-displaced fracture of the distal ulna. Physical examination demonstrates a thin woman who is in acute distress. She is tearful upon examination, and range of motion of the left forearm and wrist is limited secondary to pain. The left upper extremity is neurovascularly intact with capillary refill of less than 2 seconds. Laboratory studies are shown below:

Hemoglobin: 10.2 g/dL
Hematocrit: 32%
Leukocyte count: 7,600/mm^3 with normal differential
Platelet count: 136,000/mm^3

Serum:
Na+: 139 mEq/L
Cl-: 102 mEq/L
K+: 3.8 mEq/L
HCO3-: 26 mEq/L
Ca2+: 16.7 mg/dL
BUN: 24 mg/dL
Glucose: 101 mg/dL
Creatinine: 1.8 mg/dL
Thyroid-stimulating hormone: 2.1 µU/mL


What is the most likely explanation for this patient’s condition?