Nonselective proteinuria

In an extensive study (A4) of 88 Nigerian children with the nephrotic syndrome, 80% were observed with a nonselectivity proteinuria, and steroid therapy was ineffective in most of these ehildren. Unlike European and American children with the nephrotic syndrome, less than half of the Nigerian children who had highly selective type proteinuria showed... 

In all forms of glomerular nephritis in tropical populations in Africa, there was increased protein in the urine. In the selective proteinuria of the nephrotic syndrome most of the protein was mainly albumin and transferrin, with lower concentrations of IgG and other globulins. On the other hand, the urine of the nonselective proteinuria of the nephrotic syndrome is characterized by much higher concentrations of IgG, IgA, a2-macroglobulins, and some IgM. Differential protein clearance to establish selectivity of proteinuria has been discussed above. 

Size selectivity is probably caused by the mesh of glomerular basement proteins, which effectively restricts the passage of larger proteins with molecular weight of more than 150 kDa. Loss of size selectivity is probably the main cause of nonselective proteinuria in membranous nephropathy (SI3). 

Proteinuria in membranous nephropathy is nonselective and it is believed to be caused by the loss of size selectivity (C4). 

At any level, the proteinuria may be nonselective in that it contains the spectrum of molecular sizes. For example, when microalbuminuria is observed in the absence of low molecular weight proteinuria, it may... 

FSGS accounts for less than 15% of the cases of idiopathic nephrotic syndrome in children and about 15% to 20% in adults however, it may account for 36% to 80% of the cases in African-Americans. Almost all the patients present with proteinuria, and many of them have all the features of nephrotic syndrome. The proteinuria is nonselective, containing albumin and other higher-molecular-weight proteins, and is usually less severe when compared to patients who have minimal-change disease. Hypertension, microscopic hematuria, and renal dysfunction may be seen in up to half of the patients. Reduced renal function becomes more prevalent as the disease progresses. 

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