Which of the following conditions may indicate renal failure?

The presence of protein in urine, known as proteinuria, is a significant indicator of kidney dysfunction or renal failure. Under normal circumstances, the kidneys filter blood and prevent large molecules like proteins from passing into the urine. When the kidneys are compromised, this filtration process can fail, allowing proteins to leak into the urine. This condition can be caused by various forms of kidney damage, such as glomerulonephritis, diabetic nephropathy, or hypertension, all of which can lead to renal failure. Therefore, detecting protein in urine is a critical symptom that healthcare professionals monitor to assess kidney health and function.

Increased urine output might suggest different conditions, including diabetes or a urinary tract infection, but it does not directly indicate renal failure. Decreased body temperature is typically not associated with kidney function but rather other physiological or environmental factors. Elevated blood pressure can be a consequence of renal issues, but it is not definitive for renal failure by itself without additional symptoms or tests, such as those mentioned. Thus, identifying protein in the urine serves as a clear and direct marker for potential renal failure.