Molecular pathogenetic mechanisms of nephrotic edema: progress in understanding

Edema in Renal Diseases – Current View on Pathogenesis

Edema is a common complication of numerous renal disease. In the recent past several aspects of the pathophysiology of this condition have been elucidated. We herein present a case of nephrotic syndrome in a 30 year-old men. The discussion revolves around the following key questions on fluid accumulation in renal disease: 1. What is edema? What diseases can cause edema? 2. What are the mechanisms of edema in nephrotic syndrome? 2a. The “underfill” theory 2b. The “overfill” theory 2c. Tubulointerstitial inflammation 2d. Vascular permeability 3. What are the mechanisms of edema in nephritic syndrome? 4. How can the volume status be assessed in patients with nephrotic syndrome? 5. What are therapeutic strategies for edema management? 6. What are the factors affecting response to diuretics? 7. How can we overcome the diuretics resistance? 7a. Effective doses of loop diuretics 7b. Combined diuretic therapy 7c. Intravenous administration of diuretics 7d. Albumin infusions 7e. Alternative methods of edema management 8. Conclusion.

Expression pattern of aquaporins in patients with primary nephrotic syndrome with edema

The association between the expression of aquaporins (AQPs) in kidney tissues and the occurrence of edema in nephrotic syndrome (NS) remains unclear. The current study aimed to investigate this association. A total of 54 patients with primary glomerular disease, diagnosed by renal biopsy, were divided into three groups: Control, NS without edema and NS with edema. The expression of AQP1, AQP2, AQP3 and AQP4 in kidney tissues from these patients was assessed using immunohistochemistry, and urinary AQP concentrations were quantified by ELISA. Comparison of the three groups was conducted using one way analysis of variance, independent samples t-test or the Chi-square test. AQP1 was strongly expressed in the proximal tubules. The proportion of the AQP1-positive area in kidney tissues from patients with NS with edema was significantly reduced, in comparison with the other two groups. By contrast, the proportion of the AQP2-positive area in the NS with edema group was significantly higher than that of the other two groups; significant differences were also observed between the control and NS without edema groups for this parameter. Urinary AQP2 concentrations in patients with NS (with and without edema) were significantly higher than that of the control group, and exhibited a significant positive correlation with kidney tissue AQP2 concentrations. The present study demonstrated the abnormal expression pattern of AQP1-AQP4 in the kidney tissues of patients with NS, providing a basis for an improved understanding of the role of AQP in the pathogenesis of NS.

Role of sodium during formation of edema in children with nephrotic syndrome

BACKGROUND

The pathogenesis of edema in nephrotic syndrome is not entirely understood. The aim of this study was to contribute to the discussion on edema pathogenesis in nephrotic syndrome by following changes in volume and sodium retention for the course of the disease in children with steroid-sensitive nephrotic syndrome (SSNS).

METHODS

Forty-one children with SSNS were included in the study. The patients were divided into three groups (group I: relapse-edematous; group II: relapse-edema free; group III: remission). We investigated the value of the significance and area of sodium retention and vasoactive hormones. In addition, we measured parameters such as inferior vena cava collapsibility index, left atrium diameter, and total body water (TBW) to determine the volume load and cause of edema in children with SSNS.

RESULTS

TBW increased in the relapse-nephrotic syndrome group and the difference was statistically significant among groups (P < 0.001). However, inferior vena cava collapsibility index and left atrium diameter were not different among groups. Fractional sodium excretion was lower in children with relapse nephrotic syndrome (P < 0.05).

CONCLUSION

Although TBW increases in children with SSNS, intravascular volume is normal. In addition, hypoalbuminemia and sodium retention of the proximal tubule cause edema in children with SSNS.