Febrile Proteinuria in Hospitalized Children: Characterization of Urinary Proteins

Abstract

Background: Transient proteinuria during febrile illness is a common phenomenon. Recent studies have re-examined the pathophysiology of proteinuria and new urinary markers to characterize it, including B7-1 (CD80), which is expressed also in glomerular podocytes and influences the glomerular barrier.Aim: To investigate the pattern of proteinuria in febrile non-renal diseases, including B7-1.Methods: We prospectively analyzed urine samples of 44 febrile children and 28 afebrile controls for different protein components: albumin (glomerular marker), β2-microglobulin (tubular marker), uromodulin (Tamm Horsfall protein-THP, a renal endogenous protein) and B7-1. Febrile illness was characterized as focal bacterial vs. viral. Exclusion criteria were underlying renal disease, steroid treatment or urinary tract infection.Results: Elevated urine albumin (64.5 ± 10.3 vs. 17.8 ± 4 mg/g, mean ± S.E.M., p = 0.0009) and β2-microglobulin (1.44 ± 0.34 vs. 0.182 ± 0.03 mg/g, mean ± S.E.M., p = 0.005] and decreased uromodulin (10.5 ± 1 vs. 26.7 ± 2.2 Arbitrary units, mean ± S.E.M., p = 0.0001) excretion were found during febrile illness vs. controls. Urine B7-1 was also increased in the febrile group (0.27 ± 0.05 vs. 0.07 ± 0.01 ng/ml, mean ± S.E.M., p = 0.001), and was the only marker which was significantly higher in bacterial vs. viral disease.Conclusions: Febrile proteinuria is not generalized: while proteins of both glomerular and tubular origin increase, uromodulin decreases. Urine B7-1 is increased during fever, more significantly in bacterial infections. Thus, urinary B7-1 may be used as an additional marker to differentiate between febrile states of bacterial vs. viral origin.

Potential Acute Renal Injury in Sheep with Bluetongue Serotype 4

“…It has been attributed to a transient impairment of renal tubules to reabsorb low molecular weight proteins [26]. The pathophysiology of febrile proteinuria is not entirely elucidated, while new biomarkers are under evaluation to identify the origin of proteinuria and the possible distinction between bacterial and viral etiology [27]. In the present study, we cannot exclude that proteinuria is functional due to the febrile state.…”

Role of Formyl Peptide Receptors and β-Arrestin-1 in suPAR Signal Transduction in Mouse Podocytes: Interactions with αVβ3-Integrin

“…By responding to a wide variety of extracellular ligands associated with infections, tissue damage, and innate immunity (including suPAR), they might allow for changes in glomerular barrier function. It has long been known that patients can present with transient proteinuria, for example during respiratory infections [54], sepsis [55], fevers [56] and following exercise [57]. These transient and relatively benign proteinurias are especially common in children [58,59].…”

Evaluation of Renal Function and Urinalysis in Children With Simple Febrile Convulsions

“…Therefore, urinary B7-1 can discriminate between bacterial and viral febrile conditions. 36 On the other hand, studies indicate that information on proteinuria and eGFR together is essential for identifying individuals at risk of AKI, and the presence of proteinuria increases this risk 37 ; consequently, it is essential to examine the urine protein in these children.…”