What is a common characteristic of nephrotic syndrome?

Nephrotic syndrome is primarily characterized by significant proteinuria, which refers to an excess of protein in the urine. This condition arises due to damage to the glomeruli, the filtering units of the kidneys, leading to the loss of large amounts of albumin and other proteins. The presence of protein in the urine is one of the hallmark signs used to diagnose nephrotic syndrome and typically exceeds 3.5 grams per day.

In addition to proteinuria, nephrotic syndrome often presents other features such as edema, hypoalbuminemia (low serum albumin), and hyperlipidemia (elevated levels of lipids in the blood); however, the defining feature remains proteinuria. This excess protein leakage into the urine not only indicates the kidney's impaired filtering ability but also contributes to the symptoms and complications associated with the syndrome.

The other options, while related to renal conditions, do not specifically define nephrotic syndrome. Hematuria generally indicates the presence of blood in the urine and is more associated with glomerulonephritis or other renal pathologies. Polyuria refers to excessive urination and may occur in various conditions, such as diabetes, but is not a defining characteristic of nephrotic syndrome