Differential Diagnosis for High Immunoglobulin A and C-Reactive Protein on Blood Test

Single Most Likely Diagnosis

• Chronic Inflammatory Bowel Disease (IBD): High levels of immunoglobulin A (IgA) and C-reactive protein (CRP) are commonly seen in chronic inflammatory conditions such as Crohn's disease and ulcerative colitis, which are types of IBD. The elevated IgA suggests a mucosal immune response, while CRP indicates systemic inflammation.

Other Likely Diagnoses

• Infectious Diseases: Certain infections, especially those involving the gastrointestinal tract or respiratory system, can cause an increase in both IgA and CRP. Examples include pneumonia, diverticulitis, or gastroenteritis.
• Autoimmune Disorders: Conditions like rheumatoid arthritis, lupus, or scleroderma can lead to elevated levels of IgA and CRP due to chronic inflammation and immune system dysregulation.
• Chronic Infections: Chronic infections such as endocarditis, osteomyelitis, or abscesses can also result in elevated IgA and CRP levels.

Do Not Miss Diagnoses

• Wegener's Granulomatosis: Now known as granulomatosis with polyangiitis, this is a rare autoimmune disorder that can cause inflammation of the blood vessels and affect various organs. It is crucial to diagnose early due to its potential severity and the availability of effective treatments.
• Lymphoma: Certain types of lymphoma, particularly those involving the gastrointestinal tract, can present with elevated IgA and CRP. Early diagnosis is critical for effective management and prognosis.
• Sepsis: Although less common as a primary diagnosis for these lab findings, sepsis is a life-threatening condition that requires immediate recognition and treatment. The combination of high IgA and CRP could be seen in the context of severe infection.

Rare Diagnoses

• Selective IgA Deficiency with Compensatory Increase: This is a rare condition where there's a deficiency in IgA, but other immunoglobulins, including IgG and IgM, might be elevated in compensation, potentially leading to confusion with conditions causing high IgA levels.
• Alpha-1 Antitrypsin Deficiency: A genetic disorder that can cause lung disease and liver disease, potentially leading to elevated inflammatory markers, including CRP.
• Familial Mediterranean Fever: A genetic condition characterized by recurrent episodes of painful inflammation, which can result in elevated CRP and potentially IgA during acute episodes.