Which of the following is a complication of renal failure?

Fluid overload is a well-known complication of renal failure due to the kidneys' reduced ability to excrete excess fluids from the body. In renal failure, whether acute or chronic, the kidneys are unable to filter out waste effectively, leading to an accumulation of fluid in the body. This can result in symptoms such as edema, hypertension, and in severe cases, pulmonary edema, which can pose serious respiratory risks.

Additionally, the regulation of fluid and electrolyte balance is significantly impacted in individuals with renal failure, further exacerbating the condition. For instance, when the kidneys cannot remove excess sodium and water, this leads to increased blood volume, contributing to fluid overload.

The other options do not appropriately characterize typical complications associated with renal failure. For instance, vitamin D levels may actually be decreased in renal failure due to the kidneys' role in converting vitamin D into its active form. Hypoglycemia, while a concern in some contexts, is not a direct complication of renal failure but may be related to other conditions or treatments. Decreased blood pressure might occur in certain acute settings but is not a classic nor universal complication associated with renal failure as fluid overload is.