A 4 years old child presented with generalized edema and ascites. There was no hypeension or hematuria. Renal function tests were normal. Urinalysis revealed massive proteinuria. Most probable underlying cause is:

Generalized edema in a child with massive proteinuria, with no hypeension or hematuria & normal renal function suggests a diagnosis of Nephrotic syndrome due to minimal change disease (also known as lipoid nephrosis or nil disease) Post streptococcal glomerulonephritis- hypeension, hematuria IgA nephropathy- hematuria, h/o UI Membranous glomerulonephritis- hypeension, hematuria