Anion gap in nephrotic syndrome

Area of Science:

• Pediatric Nephrology
• Clinical Chemistry
• Medical Diagnostics

Background:

• The anion gap is a calculated measure of the difference between cations and anions in the blood.
• Low anion gap is observed in various conditions, including hypoproteinemia.
• Minimal change nephrotic syndrome (MCNS) is a common cause of kidney disease in children, characterized by proteinuria and edema.

Purpose of the Study:

• To investigate the prevalence and contributing factors of low anion gap during exacerbations in pediatric patients with minimal change nephrotic syndrome.
• To determine the correlation between anion gap and serum levels of total proteins, albumin, cholesterol, and immunoglobulins in these patients.

Main Methods:

• Anion gap was evaluated in 28 children (18 boys, 10 girls) with MCNS during 55 exacerbation episodes.
• Serum levels of total proteins, albumin, cholesterol, and immunoglobulins were measured.
• A coefficient of correlation was calculated to assess the relationship between anion gap and these serum analytes.

Main Results:

• Anion gap was significantly lower (p < 0.01) during MCNS exacerbations.
• Low anion gap strongly correlated with low serum total proteins (< 4 g/dL) and low serum albumin levels (< 1.5 g/dL).
• No significant correlation was found between low anion gap and serum cholesterol or immunoglobulin levels.

Conclusions:

• Hypoproteinemia, particularly hypoalbuminemia, is the primary cause of a low anion gap in children experiencing minimal change nephrotic syndrome exacerbations.
• Reduced serum total protein levels decrease the negative charge contribution to the anion gap, leading to its reduction.