Which of the following factors may require close monitoring while on INH?

The need for close monitoring of liver function while on isoniazid (INH) is primarily due to the potential hepatotoxicity associated with this medication. INH is an antibiotic commonly used to treat tuberculosis, and while it is highly effective, it can lead to liver damage in some individuals. This risk increases with age, the presence of existing liver disease, and when used in combination with other medications that affect liver function.

Regular liver function tests (LFTs) are essential to detect any signs of liver injury early, allowing for prompt intervention if necessary. Patients on INH should be educated about the signs and symptoms of liver dysfunction, such as jaundice, dark urine, or unexplained fatigue, which may warrant further evaluation and potential discontinuation of the drug.

Weight changes, blood pressure, and heart rate are also important to monitor in patients receiving various medications, but they are not specifically associated with INH and its risks. Therefore, prioritizing liver function assessment aligns with best practices for safely using isoniazid in tuberculosis treatment.