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Influence of serum albumin on renal function in nephrotic syndrome
1Department of Pediatrics, Huddinge University Hospital, Sweden.
Insights
Glomerular filtration rate (GFR) and filtration fraction (FF) are reduced in nephrotic syndrome, improving during remission. Low GFR is linked to an ultrafiltration coefficient, not hypoperfusion, suggesting compensatory mechanisms.
Area of Science:
- Nephrology
- Pediatric Nephrology
- Renal Physiology
Background:
- Nephrotic syndrome (NS) is a complex kidney disorder affecting children.
- Understanding renal hemodynamics in NS is crucial for management.
- GFR and ERPF are key indicators of kidney function.
Purpose of the Study:
- To evaluate glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in children with nephrotic syndrome.
- To assess changes in GFR and ERPF across different stages of the disease (nephrotic, recovery, remission).
- To explore correlations between renal function parameters and clinical factors like serum albumin and mean arterial pressure.
Main Methods:
- Measured GFR and ERPF using inulin and para-aminohippuric acid clearances.
- Studied 119 children with various types and stages of nephrotic syndrome.
- Analyzed data based on disease stage (nephrotic, recovery, remission) and histological findings.
Main Results:
- GFR was significantly lower in the nephrotic stage compared to remission and controls.
- ERPF was higher in the nephrotic stage, leading to a decreased filtration fraction (FF).
- GFR and FF increased significantly upon remission, correlating directly with serum albumin and inversely with mean arterial pressure.
Conclusions:
- GFR and FF are reduced in the nephrotic stage, normalizing in remission.
- Low GFR in nephrotic syndrome is attributed to a reduced ultrafiltration coefficient, not hypoperfusion.
- Compensatory mechanisms involving serum albumin and mean arterial pressure may counteract the reduced ultrafiltration coefficient.
Abstract:
Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), determined by the clearances of inulin and para-aminohippuric acid, were evaluated in 119 children with different types of nephrotic syndrome and in different stages: the nephrotic stage (serum albumin < 25 g/l), recovery stage (25-35 g/l), and remission (> 35 g/l). GFR in the nephrotic stage was significantly lower than in remission and in controls, and was lowest at onset of the disease (84 +/- 6, 111 +/- 4, and 119 +/- 2 ml/min per 1.73 m2). ERPF was higher in the nephrotic stage than in recovery, especially in children with histological lesions. Thus the filtration fraction (FF) was greatly decreased in the nephrotic stage. In patients investigated both in the nephrotic and the remission phase, GFR and FF increased significantly. There was a direct correlation between the serum albumin concentration and FF and an inverse correlation between mean arterial pressure (MAP) and GFR and FF in all patients, a direct correlation between the serum albumin concentration and GFR in minimal change nephrotic syndrome patients, and an inverse correlation between ERPF and serum albumin in children with histological lesions. In conclusion, GFR and FF were decreased and ERPF increased in the nephrotic stage, normalizing in remission. The low GFR in the nephrotic stage was thus not dependent on hypoperfusion. We suggest that the low GFR is dependent on a very low ultrafiltration coefficient. The direct correlation between GFR and serum albumin and the indirect correlation between GFR and MAP suggest compensatory mechanisms that increase the ultrafiltration pressure to counteract the severely reduced ultrafiltration coefficient.