In a preliminary investigation into the behaviour of low molecular weight proteins in the nephrotic syndrome, we have measured urinary concentrations of albumin, α-1-microglobulin (α1-m) and retinol-binding protein (RBP) in six children for up to 11 days during the course of steroid therapy for nephrotic syndrome.
The results in part support the concept of independent proximal tubular absorption of albumin and low molecular weight proteins, and indicate that in the nephrotic syndrome the excretion of RBP and α1-m, two generally accepted markers of tubular proteinuria, is anomalous.
HardwickeJ.Laboratory aspects of proteinuria in human disease. Clin Nephrol1975; 3: 37–41.
2.
HallCLHardwickeJ.Low molecular weight proteinuria. Ann Rev Med1979; 30: 199–211.
3.
MaackTJohnsonVKauSTRenal filtration, transport and metabolism of low-molecular-weight proteins: A review. Kidney Int1979; 16: 251–70.
4.
BeethamRDawnayACattellW.The effect of a synthetic polypeptide on the renal handling of protein in man. Clin Sci1987; 72: 245–9.
5.
BernardAViauCOuledALauwerysR.Competition between low- and high-molecular weight proteins for renal tubular uptake. Nephron1987; 45: 115–18.
6.
PetersonPAEvrinP-EBerggardI.Differentiation of glomerular, tubular and normal proteinuria: Determination of urinary excretion of β2-microglobulin, albumin and total protein. J Clin Invest1969; 48: 1189–98.
7.
BernardAMMoreauDLauwerysR.Comparison of retinol-binding protein and β2-microglobulin determination in urine for the early detection of tubular proteinuria. Clin Chim Acta1982; 126: 1–7.
8.
YuHYanagisawaYForbesMAAlpha-1-microglobulin: An indicator protein for renal tubular function. J Clin Pathol1983; 36: 253–9.
9.
DonaldsonMDCChambersREWoolridgeMWStability of alpha1-microglobulin, beta2-microglobulin and retinol binding protein in urine. Clin Chim Acta1989; 179: 73–8.
10.
BeethamRDawnayALandonJA radioimmunoassay for retinol-binding protein in serum and urine. Clin Chem1985; 31: 1364–7.
11.
BernardAVyskocylAMahieuPLauwerysR.Effect of renal insufficiency on the concentration of free retinol-binding protein in urine and serum. Clin Chim Acta1988; 171: 85–94.
12.
KanaiMRazAGoodmanDS. Retinol-binding protein: The transport protein for vitamin A in human plasma. J Clin Invest 1968; 47: 2025–44.
13.
TejlerLGrubbAO. A complex-forming glycoprotein heterogenous in charge and present in human plasma, urine and cerebrospinal fluid. Biochim Biophys Acta1976; 439: 82–94.