Which of the following is a common consequence of renal failure?

Fluid retention is a common consequence of renal failure due to the kidneys' decreased ability to filter and excrete excess fluids and waste products from the body. When the kidneys are not functioning properly, they can become unable to remove enough sodium and water, leading to a buildup of fluid in the tissues and cavities, which is known as edema. This retention can cause swelling, increased blood pressure, and strain on the cardiovascular system, all of which are significant concerns in patients with renal failure.

In contrast, the other options suggest improvements or normal physiological functions that do not typically occur in renal failure. Increased energy levels and improved kidney function are generally not outcomes associated with renal impairment, as these conditions often lead to fatigue and reduced kidney efficacy. Normal blood pressure is also unlikely, as many patients with renal failure experience hypertension due to fluid overload and other metabolic changes.