Differential Diagnosis for Autoimmune Disease with Low C3 and C8 and Anemia
- Single most likely diagnosis:
- Systemic Lupus Erythematosus (SLE): This is a common autoimmune disease that can cause low levels of complement components, including C3 and C8, due to consumption during inflammation. Anemia is also a frequent finding in SLE, often due to chronic disease or autoimmune hemolytic anemia.
- Other Likely diagnoses:
- Membranoproliferative Glomerulonephritis (MPGN): This kidney disease can lead to low levels of complement components, including C3, and can be associated with anemia due to chronic kidney disease. Some forms of MPGN are caused by autoimmune mechanisms.
- Sjögren's Syndrome: Although less commonly associated with low C3 and C8, Sjögren's Syndrome is an autoimmune disease that can cause anemia and occasionally affects the complement system.
- Do Not Miss diagnoses:
- Atypical Hemolytic Uremic Syndrome (aHUS): This rare but life-threatening condition can cause low C3 levels due to alternative pathway dysregulation and is associated with anemia due to hemolysis. It's crucial to consider aHUS due to its severe prognosis and need for specific treatment.
- Post-streptococcal Glomerulonephritis (PSGN): Although typically associated with low C3, PSGN can occasionally affect C8 levels and cause anemia. It's essential to diagnose PSGN promptly due to its potential for renal complications.
- Rare diagnoses:
- C3 Glomerulopathy: A group of rare diseases characterized by abnormal control of the complement system, leading to C3 deposition in the kidney and low serum C3 levels. Anemia can occur due to chronic kidney disease.
- Chronic Cold Agglutinin Disease: A rare autoimmune hemolytic anemia that can be associated with low C3 and C8 levels in some cases, particularly if there's an underlying condition affecting the complement system.