What condition can be identified by protein in the urine?

The presence of protein in the urine, known as proteinuria, is a significant indicator of nephrotic syndrome. This condition is characterized by a specific set of symptoms including significant protein loss through the urine, low levels of protein in the blood, and swelling (edema) in various parts of the body. Nephrotic syndrome occurs due to damage to the filtering units of the kidneys, leading to increased permeability which allows proteins to leak into the urine.

In contrast, while chronic kidney disease may manifest with proteinuria, it is a generalized term that encompasses various kidney impairments and does not solely indicate nephrotic syndrome. Hypertension can have a variety of causes and may or may not involve proteinuria, depending on the underlying issues affecting kidney function. Interstitial cystitis, a chronic condition affecting the bladder, typically does not feature proteinuria as a symptom.

Thus, nephrotic syndrome is the specific condition most directly identified by the presence of protein in the urine, making it the answer that aligns best with the question.