A nurse is caring for a client who is taking lovastatin and has a new prescription for ezetimibe to lower cholesterol levels.
Which of the following laboratory values should the nurse monitor?

Choice A rationale

A history of migraine headaches is not a contraindication for metformin. Metformin's primary mechanism involves reducing hepatic glucose production and improving insulin sensitivity in peripheral tissues. Migraine headaches are neurological conditions not directly influenced by or interacting adversely with metformin's metabolic actions.

Choice B rationale

Alcohol use disorder is a significant contraindication for metformin due to an increased risk of lactic acidosis. Alcohol consumption can impair hepatic lactate metabolism and increase lactate production, while metformin itself can elevate lactate levels. The combination markedly raises the likelihood of this severe metabolic complication.

Choice C rationale

A history of peptic ulcer disease is not a direct contraindication for metformin. While some gastrointestinal side effects like nausea or diarrhea can occur with metformin, these are generally not severe enough to preclude its use in patients with a history of peptic ulcer disease, especially if the ulcer is currently resolved.

Choice D rationale

Tobacco use is not a direct contraindication for metformin. While tobacco use is a risk factor for various health issues, including cardiovascular disease and complications of diabetes, it does not physiologically interact with metformin in a manner that would contraindicate its use. The primary concerns with tobacco are unrelated to metformin's metabolism or side effect profile.

Choice A rationale: Persistent coughing with mucopurulent sputum suggests an ongoing respiratory infection or inflammation. Mucopurulent sputum indicates the presence of neutrophils and bacteria, often seen in bacterial pneumonia or tuberculosis. While significant, coughing alone is not an immediate life-threatening finding but rather a symptom requiring monitoring and further diagnostic follow-up to confirm the cause.

Choice B rationale: Joint pain in a patient receiving infliximab for rheumatoid arthritis may reflect an autoimmune flare or side effects of immunosuppression. Although uncomfortable and significant for quality of life, joint pain does not usually require immediate intervention compared to respiratory or infectious signs that may threaten life or transmission risk.

Choice C rationale: Anorexia, or decreased appetite, is a common systemic symptom in chronic infections like tuberculosis. It reflects the body’s inflammatory response and catabolic state but is a nonspecific finding. It requires addressing nutritional support but is not immediately life-threatening or requiring urgent intervention compared to active infectious disease signs.

Choice D rationale: Night sweats are a classic systemic symptom of tuberculosis caused by cytokine-mediated thermoregulatory dysfunction during infection. Although important in clinical suspicion, night sweats themselves do not necessitate immediate intervention but support the need for further diagnostic workup and infection control precautions.

Choice E rationale: An 11 mm induration on the purified protein derivative (PPD) test is considered positive in this patient due to immunosuppression with infliximab, which increases TB risk. The normal cutoff varies by risk factors, but 5 mm or greater is positive in immunosuppressed patients. This finding requires urgent follow-up to initiate treatment and prevent active disease and transmission, making it the most critical.