Differential Diagnosis for Elevated IgM

Given the patient's IgM level is 253, we can consider the following differential diagnoses:

• Single Most Likely Diagnosis
  • Infectious Mononucleosis: This condition, caused by Epstein-Barr virus (EBV), is a common cause of elevated IgM levels, especially in young adults. The clinical presentation often includes fever, sore throat, and lymphadenopathy.
• Other Likely Diagnoses
  • Primary Sjögren's Syndrome: An autoimmune disorder characterized by exocrine gland inflammation, which can lead to elevated IgM levels. Patients often present with dry eyes and dry mouth.
  • Waldenström's Macroglobulinemia: A type of non-Hodgkin lymphoma that can cause elevated IgM levels, leading to hyperviscosity syndrome. Symptoms may include fatigue, weight loss, and neurological abnormalities.
  • Infections (e.g., CMV, Toxoplasmosis): Certain infections can cause a temporary increase in IgM levels. The clinical presentation will depend on the specific infection.
• Do Not Miss Diagnoses
  • Multiple Myeloma: Although less likely, multiple myeloma can cause elevated IgM levels. It is essential to rule out this diagnosis due to its significant implications for patient management and prognosis.
  • Lymphoma (e.g., Burkitt's, Follicular): Other types of lymphoma can also lead to elevated IgM levels. Early detection is crucial for effective treatment.
• Rare Diagnoses
  • Heavy Chain Disease: A rare condition characterized by the production of abnormal heavy chains, which can cause elevated IgM levels. Patients may present with symptoms such as diarrhea, weight loss, and abdominal pain.
  • Good's Syndrome: A rare immunodeficiency disorder that can lead to elevated IgM levels. Patients often have recurrent infections and may present with autoimmune features.