When BAL has been administered for arsenic poisoning, which laboratory test should be closely monitored?

When BAL (British Anti-Lewisite), which is a chelating agent, is administered for arsenic poisoning, it is essential to closely monitor blood urea nitrogen (BUN) levels. This is because BAL can influence kidney function, and the kidneys play a crucial role in filtering toxins and waste products from the bloodstream, including those that may arise from both the poisoning and the treatment process.

As the kidneys are responsible for excreting substances from the body, any impairment in kidney function as a result of the poisoning or treatment can lead to an accumulation of nitrogenous waste, reflected by elevated BUN levels. This monitoring is critical for ensuring the patient's renal health and adjusting treatment if necessary to prevent potential complications such as acute kidney injury or further toxicity.

While other options may be relevant in various contexts, monitoring BUN specifically highlights the importance of assessing renal function in the aftermath of arsenic toxicity and the therapeutic intervention with BAL.