QUANTITATIVE AND QUALITATIVE-ANALYSIS OF FEBRILE PROTEINURIA IN CHILDREN

In a prospective study incidence, duration and pattern of febrile prot einuria in 31 children with febrile illness (body temperature >38.5 de grees C) were investigated by sodium dodecyl sulphate polyacrylamide g el electrophoresis (SDS-PAGE) and quantitative measurement of urinary total protein, IgG, transferrin, albumin, alpha(1)-microglobulin and r etinol binding protein using an immunoluminometric assay. All children had normal renal function (GFR). Urinary total protein was elevated i n only 39% of all patients whereas 58% revealed pathologic patterns of proteinuria applying SDS-PAGE and 61% had elevated urinary levels of one or more specific proteins. The urinary proteins excreted during fe ver showed a tubular pattern, only 4 (13%) children revealed a mixed g lomerular and tubular pattern of proteinuria. A weak correlation betwe en level of body temperature and urinary protein excretion was only fo und for alpha(1)-microglobulin. Febrile proteinuria was of short durat ion and already on the fourth day free of fever no longer detectable. Patterns of febrile proteinuria did not differ between viral and bacte rial infections. The short duration as well as the prevalence of tubul ar patterns of proteinuria suggest that most likely acute phase reacta nts or cytokines lead to a temporary tubular dysfunction during episod es of fever rather than an antigen-antibody induced abnormal glomerula r permeability.