Differential Diagnosis for 46-year-old Woman with Euthyroid Hashimoto's and Recent COVID-19 Infection

Single Most Likely Diagnosis

• Post-COVID-19 Inflammatory Response: Given the patient's recent COVID-19 infection 12 weeks ago, an ongoing inflammatory response could explain the elevated WBC count. The normal CRP and ferritin levels might suggest a resolving or mild inflammatory process, but the body's response can be variable.

Other Likely Diagnoses

• Hashimoto's Thyroiditis Flare: Although the patient is euthyroid, Hashimoto's can have periods of inflammation that might not always correlate with thyroid function tests. The elevated WBC could be a sign of an autoimmune flare.
• Viral or Bacterial Infection: The elevated WBC count could indicate a new or unresolved infection. The lack of CRP elevation does not rule out infection, especially viral infections which may not always cause a significant CRP rise.
• Muscle Injury or Stress: The slightly elevated CK-MB could suggest muscle damage or stress, which might be related to the recent COVID-19 infection or another cause of muscle injury.

Do Not Miss Diagnoses

• Hematological Malignancy (e.g., Leukemia): Although less likely, an elevated WBC count warrants consideration of hematological malignancies. These conditions can present subtly and would be critical to diagnose early.
• Sepsis or Severe Infection: Despite the lack of systemic signs of infection (normal CRP, no fever mentioned), sepsis or a severe infection could present atypically, especially in someone with a recent history of COVID-19, which might have compromised their immune response.
• Autoimmune Hemolytic Anemia: Although the RBC count is normal, autoimmune conditions like Hashimoto's can be associated with other autoimmune phenomena, including hemolytic anemia. Monitoring for signs of hemolysis is important.

Rare Diagnoses

• Wilson's Disease: The elevated copper level in the blood could be a red herring or indicative of Wilson's disease, a rare genetic disorder leading to copper accumulation. However, this would typically be associated with other signs of liver or neurological disease.
• Macrophage Activation Syndrome: A rare condition that can occur in the context of autoimmune diseases or infections, characterized by an overwhelming inflammatory response. The normal ferritin levels make this less likely, but it remains a consideration in complex cases.