Which metabolic abnormality is caused by cyclosporine ?
**Core Concept**
Cyclosporine, an immunosuppressive agent, is known to cause a specific metabolic abnormality due to its inhibitory effect on a crucial enzyme in the metabolic pathway. This enzyme plays a vital role in the breakdown of a particular amino acid.
**Why the Correct Answer is Right**
Cyclosporine inhibits the activity of the enzyme cyclosporine-sensitive aminopeptidase, which breaks down the amino acid leucine. This inhibition leads to an accumulation of leucine in the blood, causing hyperleucinemia. The resulting metabolic abnormality is a hyperleucinemia, specifically an increase in the plasma concentration of leucine.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because cyclosporine does not cause a decrease in blood glucose levels, which is associated with another class of medications.
**Option B:** This option is incorrect because cyclosporine does not inhibit the activity of aminotransferases, which are involved in the transfer of amino groups between amino acids and alpha-keto acids.
**Option C:** This option is incorrect because cyclosporine does not cause an increase in the plasma concentration of branched-chain amino acids, which is associated with another metabolic disorder.
**Clinical Pearl / High-Yield Fact**
Remember that cyclosporine-induced hyperleucinemia is a significant side effect of this immunosuppressive agent and can lead to complications such as hyperammonemia and hepatic encephalopathy.
**Correct Answer: D. Hyperleucinemia.**