In acute renal failure, metabolic acidosis is due to
**Core Concept**
In acute renal failure, the kidneys' ability to regulate acid-base balance is impaired, leading to the accumulation of acidic metabolites and a decrease in bicarbonate levels. This results in metabolic acidosis. The kidneys normally excrete excess hydrogen ions and reabsorb bicarbonate ions to maintain acid-base homeostasis.
**Why the Correct Answer is Right**
The correct answer is due to the kidneys' failure to excrete excess hydrogen ions and reabsorb bicarbonate ions. In acute renal failure, the kidneys are unable to adequately perform these functions, leading to an accumulation of acidic metabolites and a decrease in bicarbonate levels. This results in a net acid load, which the body attempts to compensate for by using buffering systems, such as the bicarbonate buffering system. However, in the setting of acute renal failure, these buffering systems are overwhelmed, leading to a persistent metabolic acidosis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the pathophysiology of metabolic acidosis in acute renal failure.
**Option B:** This option is incorrect because it is not directly related to the pathophysiology of metabolic acidosis in acute renal failure.
**Option C:** This option is incorrect because it is a consequence of chronic renal failure, not acute renal failure.
**Clinical Pearl / High-Yield Fact**
In the setting of acute renal failure, metabolic acidosis is often associated with a high anion gap, which can be estimated using the formula: High Anion Gap = Sodium - (Chloride + Bicarbonate). This can help differentiate between metabolic acidosis due to renal failure and other causes.
**Correct Answer:** C.