Ann Clin Biochem 1992; 29: 450-453
Original Article
Urinary albumin and low molecular weight protein excretion in the nephrotic syndrome-sequential studies during corticosteroid treatment Robert Beetham and David Newman! From the Protein Reference Unit, Department ofImmunology, Westminster Hospital, London SW1 and 'Department of Clinical Biochemistry, London Hospital Medical School, Turner Street, London £1, UK
In a preliminary investigation into the behaviour of low molecular weight proteins in the nephrotic syndrome, we have measured urinary concentrations of albumin, a-l-microglobulin (al-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 al-m, two generally accepted markers of tubular proteinuria, is anomalous. SUMMARY.
Additional key phrases: nephrotic syndrome; armicroglobulin; urinary retinol-binding protein
At least two major patterns of proteinuria have been recognized for a number of years. In glomerular proteinuria I there is increased glomerular filtration and subsequent excretion of normally retained proteins with M R (relative molecular mass) greater than 50 000, e.g, albumin, transferrin, immunoglobulin G. In tubular proteinuria I there is increased excretion of proteins of M R less than 40000 which are, in health, relatively unhindered by the glomerular filter and almost completely absorbed in the proximal renal tubule. While certain pathologies affect both glomerulus and tubule and result in the two patterns occurring together, it has been stated that in the nephrotic syndrome the urinary clearance and metabolism of low molecular weight (LMW) proteins remain normal despite glomerular filtration and urinary loss of large amounts of high molecular weight proteins.l This is believed to reflect the fact that the lesion giving rise to the increased glomerular filtration of the normally retained larger proteins has no major effect on the filtration of the smaller proteins." Nevertheless, the above observation Correspondence: Dr R Beetham, Biochemistry Department, Frenchay Hospital, Bristol BS16 lLE, UK.
urinary
albumin;
urinary
also implies that there is no effect of the increased filtered load of the larger proteins on the tubular absorption of the LMW proteins. At present there is evidence to support both independent" and commons tubular reabsorption mechanisms for filtered protein. Detailed examination of the literature in fact shows modest elevations of 132-microglobulin
Original Article
Urinary albumin and low molecular weight protein excretion in the nephrotic syndrome-sequential studies during corticosteroid treatment Robert Beetham and David Newman! From the Protein Reference Unit, Department ofImmunology, Westminster Hospital, London SW1 and 'Department of Clinical Biochemistry, London Hospital Medical School, Turner Street, London £1, UK
In a preliminary investigation into the behaviour of low molecular weight proteins in the nephrotic syndrome, we have measured urinary concentrations of albumin, a-l-microglobulin (al-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 al-m, two generally accepted markers of tubular proteinuria, is anomalous. SUMMARY.
Additional key phrases: nephrotic syndrome; armicroglobulin; urinary retinol-binding protein
At least two major patterns of proteinuria have been recognized for a number of years. In glomerular proteinuria I there is increased glomerular filtration and subsequent excretion of normally retained proteins with M R (relative molecular mass) greater than 50 000, e.g, albumin, transferrin, immunoglobulin G. In tubular proteinuria I there is increased excretion of proteins of M R less than 40000 which are, in health, relatively unhindered by the glomerular filter and almost completely absorbed in the proximal renal tubule. While certain pathologies affect both glomerulus and tubule and result in the two patterns occurring together, it has been stated that in the nephrotic syndrome the urinary clearance and metabolism of low molecular weight (LMW) proteins remain normal despite glomerular filtration and urinary loss of large amounts of high molecular weight proteins.l This is believed to reflect the fact that the lesion giving rise to the increased glomerular filtration of the normally retained larger proteins has no major effect on the filtration of the smaller proteins." Nevertheless, the above observation Correspondence: Dr R Beetham, Biochemistry Department, Frenchay Hospital, Bristol BS16 lLE, UK.
urinary
albumin;
urinary
also implies that there is no effect of the increased filtered load of the larger proteins on the tubular absorption of the LMW proteins. At present there is evidence to support both independent" and commons tubular reabsorption mechanisms for filtered protein. Detailed examination of the literature in fact shows modest elevations of 132-microglobulin
