USA Biology Olympiad (USABO) Practice Exam

Which physiological change is commonly associated with kidney failure?

1. Increased urine output

2. Lower potassium levels

3. Higher concentration of waste products in blood

4. Decrease in blood pressure

The correct answer is: Higher concentration of waste products in blood

In the context of kidney failure, a key physiological change is the accumulation of waste products in the blood, which occurs as the kidneys lose their ability to filter and excrete these substances effectively. Under normal circumstances, the kidneys regulate waste removal from the bloodstream, maintain fluid and electrolyte balance, and help manage blood pressure. When kidney function declines, waste products such as urea, creatinine, and other nitrogenous substances begin to build up in the blood, leading to a condition known as uremia. This buildup can result in various symptoms and health complications, as the body cannot efficiently eliminate these toxins. Increased urine output typically does not occur in kidney failure; rather, it is often a symptom of conditions such as diabetes insipidus or after certain types of acute kidney injury. If the kidneys are severely damaged or have completely failed, urine output may decrease significantly. Lower potassium levels are generally not associated with kidney failure. In fact, kidney failure often leads to elevated potassium levels (hyperkalemia) due to the kidneys' inability to excrete potassium efficiently. Blood pressure changes can vary in kidney failure, but a decrease in blood pressure is not a common characteristic. In many cases, kidney failure can lead to hypertension due to fluid overload and alterations