The Spectrum of Kidney Diseases in Children Associated with Low Molecular Weight Proteinuria

BACKGROUND: Proteinuria, in addition to haematuria, is the most important laboratory parameter in patients with nephro-urological diseases. Low molecular weight proteinuria (LMWP) is of particular importance because some diseases genetic and tubulointerstitial are diagnosed based on its presence. AIM: The purpose of this study is to describe the clinical features, the course and outcome of pediatric patients with a renal disease associated with LMWP. MATERIAL AND METHODS: This retrospective observational study included 250 pediatric patients with various kidney diseases in which the type of proteinuria was defined by 4-20% gradient gel sodium dodecyl sulphate polyacrylamide gel (SDS-PAG) electrophoresis. RESULTS: Isolated LMWP was detected in 12% of patients, while mixed glomerulotubular proteinuria was detected in 18% of patients. It was detected in all patients with the Dent-1/2 disease, Lowe’s syndrome and secondary Fanconi syndrome. Transient LMWP was also detected in a series of 12 patients with distal renal tubular acidosis. In patients with nephrotic syndrome, it was associated with corticoresistence and unfavourable clinical course. CONCLUSION: This study contributes to the understanding of the clinical spectrum of various kidney diseases associated with LMWP, their natural course, and the effect of therapy.