Raised urinary fibrin-degradation products, complement, and IgG during an influenza-like illness

Urine from eight normal controls in whom an influenza-like illness developed contained high concentrations of fibrin-degradation products (F.D.P.), IgG, and C3. The study was carried out when influenza A was prevalent in the community. However, a wide range of serological investigations revealed no evidence for influenza A or other viruses. The infection may have been caused by other viruses which produce upper-respiratory-tract infections and which are not readily diagnosed by serology. Urinary fibrin-degradation products are a well-known marker of glomerulonephritic activity and viral antigens may have induced an immune-complex glomerulonephritis in the 8 controls in whom an influenza-like disease developed. A larger normal population should be investigated during a virus epidemic.