Differential Diagnosis for Post-Ferumoxytol Infusion Symptoms

The symptoms described, including sore shoulders and back, subluxated left shoulder, nausea, and extreme fatigue following ferumoxytol infusions, can be approached by considering various potential causes. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Hypersensitivity reaction to ferumoxytol: This is a common adverse effect associated with intravenous iron preparations like ferumoxytol. Symptoms can range from mild to severe and include musculoskeletal pain, nausea, and fatigue, aligning with the described symptoms.
• Other Likely Diagnoses
  • Iron overload: Although less common with ferumoxytol compared to other iron supplements, excessive iron levels can lead to symptoms like joint pain and fatigue.
  • Musculoskeletal strain: The subluxation and musculoskeletal pain could be related to strain or overuse, potentially exacerbated by the infusion process or positioning during the procedure.
  • Anaphylactoid reaction: Similar to hypersensitivity reactions but may involve more systemic symptoms. While less common, it's a consideration given the timing and nature of the symptoms.
• Do Not Miss Diagnoses
  • Anaphylaxis: A severe, life-threatening allergic reaction that requires immediate medical attention. Although the symptoms described do not fully align with anaphylaxis, any allergic reaction to a medication warrants consideration of this diagnosis.
  • Adverse drug reaction leading to systemic inflammation: Certain reactions can lead to widespread inflammation, affecting multiple systems and potentially causing severe fatigue, nausea, and musculoskeletal symptoms.
• Rare Diagnoses
  • Connective tissue disease flare: In patients with pre-existing connective tissue diseases (e.g., rheumatoid arthritis, lupus), certain medications can trigger disease flares, leading to symptoms like joint pain and fatigue.
  • Neurological disorders: Certain conditions, like neuropathic pain syndromes or neuromuscular diseases, could potentially be exacerbated by the infusion, although this would be less directly related to ferumoxytol itself.

Each of these diagnoses should be considered in the context of the patient's full medical history, the timing of symptoms relative to the infusion, and other potential exposures or conditions that could contribute to the symptoms. A thorough evaluation, including potentially consulting with specialists such as rheumatologists or allergists, may be necessary to determine the underlying cause.