34 year-old man with psych hx and seasonal AR c/o swelling since 2/2017 on buttocks, feet, hands, tongue, uvula. No GI sx, arthralgias, fever or rash. Occurs every few days -last 1-48 hrs. Worse with exertion, contact. C4 = 10.8 and 11.6(both dec), C3, ANA, SPEP, C1 est serum and fn, C1q all normal. I think this is idiopathic angioedema but any explanation for low C4 in light of other values being normal?


The low C4 and normal C3 would suggest additional diagnoses of SLE, mixed cryoglobulinemia, and membranoproliferative glomerulonephritis. If the cryoglobulins are positive, then could consider hepatitis B and C.

Patricia McNally, MD, FAAAAI


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