Commonest type of nephrotic syndrome seen in children –
**Core Concept**
Nephrotic syndrome is a clinical disorder characterized by massive proteinuria (>3.5 g/1.73 m^2/day), hypoalbuminemia, hyperlipidemia, and edema. In children, the most common cause of nephrotic syndrome is a condition that affects the glomerular filtration barrier.
**Why the Correct Answer is Right**
The commonest type of nephrotic syndrome seen in children is minimal change disease (MCD). This condition is characterized by the loss of foot processes of the podocytes, leading to a disruption of the glomerular filtration barrier. As a result, large amounts of protein are lost in the urine. The exact pathogenesis of MCD is not fully understood, but it is believed to involve immune system dysfunction and the production of antibodies against the glomerular basement membrane.
**Why Each Wrong Option is Incorrect**
**Option A:** Focal segmental glomerulosclerosis (FSGS) is a type of nephrotic syndrome, but it is less common in children than minimal change disease. FSGS is characterized by scarring of the glomeruli, which leads to a loss of filtration surface area and proteinuria.
**Option B:** Membranous nephropathy is a cause of nephrotic syndrome, but it is more common in adults than in children. This condition is characterized by the thickening of the glomerular basement membrane, which leads to a loss of protein in the urine.
**Option C:** IgA nephropathy is a cause of nephrotic syndrome, but it is not the most common type seen in children. This condition is characterized by the deposition of IgA antibodies in the glomeruli, which leads to inflammation and proteinuria.
**Option D:** Lupus nephritis is a type of nephrotic syndrome, but it is not the most common type seen in children. This condition is characterized by the deposition of immune complexes in the glomeruli, which leads to inflammation and proteinuria.
**Clinical Pearl / High-Yield Fact**
Minimal change disease is the most common cause of nephrotic syndrome in children and is often associated with a good prognosis, with many children experiencing complete remission with steroid treatment.
**Correct Answer: C. IgA nephropathy is a cause of nephrotic syndrome, but it is not the most common type seen in children. This condition is characterized by the deposition of IgA antibodies in the glomeruli, which leads to inflammation and proteinuria.