Tubular Dysfunction in Nephrotic Syndrome: Incidence and Prognostic Implications

Abstract

Although some cases of tubular dysfunction (TD) associated with nephrotic syndrome have been described, the incidence and the characteristics of this complication remain unknown. We investigated the presence of TD (renal glycosuria, aminoaciduria, metabolic acidosis with normal anion gap, hypouricaemia, and throughout hypophosphataemia) in 36 patients with nephrotic syndrome. Ten patients (group 1) showed glycosuria at some time during the course of their illness, ranging from 2.5 to 11.2 g/24 h. In addition, seven of them had metabolic acidosis with normal anion gap, five aminoaciduria, and two hypouricaemia. Membranous glomerulonephritis was the most frequent aetiology in group 1 patients (7 of 10). Proteinuria and serum creatinine (SCr) were significantly higher in group 1 patients than in the 26 remaining patients without TD (group 2): 10.2 +/- 3.7 versus 6.7 +/- 2.9 g/24 h (P less than 0.01) and 3.2 +/- 1.9 versus 1.6 +/- 0.9 mg/dl (P less than 0.05) respectively. The appearance of TD coincided with a clear worsening of renal function in most of group 1 patients. In addition, at the end of follow-up, SCr had increased from 3.2 +/- 1.9 to 5.6 +/- 3.3 mg/dl (P less than 0.05) in this group. In contrast, SCr did not show significant changes in group 2 (1.6 +/- 0.9 versus 2.1 +/- 2.2 mg/dl). In conclusion, a significant proportion (27.7%) of patients with nephrotic syndrome present TD data at some moment of their course; the appearance of this complication appears to be a sign of poor prognosis.

Glycosuria in glomerular diseases: histopathology and clinical correlations

“…Histological studies in the literature suggest the association of glycosuria with focal glomerulosclerosis, particularly in children (2,3). In our adult population we found various histological lesions in glycosuric patients and membranous glomerulonephritis was the most common form, in agreement with previously reported data (1). Other histological forms were focal glomerulosclerosis (5 cases), membranoproliferative glomerulonephritis (3 cases), mesangial IgA glomerulonephritis (1 case), and minimal change nephropathy (2 cases).…”

“…Several causes have been proposed to justify tubular dysfunction with glycosuria in these patients. Praga et al (1) suggested a possible role of renal vein thrombosis in these patients but rejected this possibility because the patients showed no clinical-laboratory signs of the disorder.…”

“…Tubular dysfunction is not uncommon in glomerular diseases and is frequently detected by the appearance of glycosuria. Praga et al (1) found 10 patients with glycosuria among 36 patients with nephrotic syndrome. Most of the patients reported in the literature were children with focal glomerulosclerosis, but some recent reports in adults point to membranous glomerulonephritis as the prevailing glomerular disease when there is glycosuria (1).…”

Diagnostic value of urinary retinol-binding protein in childhood nephrotic syndrome

“…Tubular proteinuria is present in idiopathic nephrotic syndrome [1][2][3]. Tubular proteinuria includes markers of tubular damage and dysfunction such as N-acetyl-β-Dglucosaminidase (NAG) and retinol-binding protein (RBP), respectively.…”

Individual nephron proteomes connect morphology and function in proteinuric kidney disease

“…S4A). One of the key tasks of the proximal tubule is the reabsorption of metabolites, such as amino acids, and disruption of this function results in aminoaciduria, which is occasionally observed in nephrotic patients (22,23). Quantitative analysis (Wt1het vs wildtype) revealed that the amino acid carriers SLC3A1, SLC13A3 and SLC6A20a/b were decreased in single Wt1het mouse proximal tubules ( Fig.…”