Which of the following should be monitored in a client taking rifabutin for Mycobacterium avium complex?

Monitoring for signs of hepatitis is crucial for a client taking rifabutin due to the potential hepatotoxic effects of the medication. Rifabutin can cause liver toxicity, which may manifest as elevated liver enzymes or symptoms such as jaundice, dark urine, fatigue, or abdominal pain. Regular monitoring of liver function tests (LFTs) is recommended to assess for any adverse effects on the liver, especially since individuals on prolonged therapy or those with pre-existing liver conditions are at a higher risk.

While other options may involve monitoring in different clinical contexts, they do not directly relate to the use of rifabutin. For example, although vision changes could be a concern in some medications, rifabutin is not particularly associated with this side effect compared to its risk of causing liver dysfunction. Similarly, while monitoring for fevers is important in general for infections, it is not specifically critical for rifabutin. Lastly, thyroid function tests may be relevant for other medications but are not a primary concern with rifabutin usage. Thus, focusing on the signs and symptoms of hepatitis is the most relevant and necessary action to ensure patient safety while taking rifabutin.