What is the primary symptom of nephrotic syndrome?

In nephrotic syndrome, the primary symptom is significant proteinuria, which is the presence of an excessive amount of protein in the urine. This condition arises from damage to the glomeruli, the filtering units of the kidneys, which allows large amounts of protein, particularly albumin, to leak into the urine.

When significant proteinuria occurs, it can lead to a decrease in serum protein levels, causing symptoms such as swelling (edema), especially around the eyes and in the lower extremities. This is a hallmark of nephrotic syndrome and helps distinguish it from other renal conditions. While hematuria (blood in urine), frequent urination, and abdominal pain can be associated with various urinary and kidney conditions, they are not primary features of nephrotic syndrome. The presence of significant proteinuria is what defines and characterizes this syndrome, making it the most crucial symptom to identify.