What is a common clinical sign of nephritis?

Nephritis, which refers to inflammation of the kidneys, can lead to a number of clinical signs, one of which is swelling of the extremities. The kidneys play a critical role in regulating fluid balance in the body. In nephritis, the inflammation can result in compromised kidney function, leading to fluid retention. This retention can cause edema, particularly in the extremities, as the body has difficulty eliminating excess fluid.

While other options may present symptoms associated with different renal issues or other conditions, they are not as directly linked to nephritis as swelling of the extremities. High blood pressure is indeed a potential complication of kidney problems but is more of a result of the condition rather than a direct sign of nephritis itself. Painful urination and fever can be observed in conditions affecting the urinary tract or in infections, but they are not specific clinical indicators of nephritis. Thus, swelling of the extremities directly reflects the consequences of kidney dysfunction that can occur in nephritis, making it the most accurate choice among the options provided.