Transient proteinuria is a common pathological finding in several illness states such as fever, sepsis, trauma and anaphylaxis, without an apparent renal disease. Several studies in the past have described transient proteinuria during febrile illness. B7-1 (CD80) protein has been shown to mediate proteinuria by directly affecting the glomerular podocyte 3-dimensional structure.
Methods: In this study we prospectively analyzed urine samples of 44 children with febrile (but not renal) diseases for different protein components: albumin (as glomerular injury marker), β2-microglobulin (tubular marker),uromodulin (Tamm Horsfall protein- THP, a renal endogenous protein) and B7-1 . Febrile illnesses were characterized as focal bacterial Vs viral.
Results: Elevated urine albumin and β2-microglobulin and decreased uromodulin excretion were found during febrile illness. Most of total urine protein was neither albumin nor β2-microglobulin. Urine B7-1 was increased in the study group versus controls and was significantly higher in fever due to bacterial disease versus viral.
Conclusions: children with fever show elevation of urinary proteins of both glomerular and tubulointerstitial origin, but uromodulin excretion is decreased. There is a significant fraction of yet unidentified proteins in urine during fever. Urine B7-1 is also increased, more significantly in bacterial infections. Thus, urinary B7-1 may be a useful marker to differentiate between febrile states of bacterial and viral origin.
