What laboratory value should be monitored in a patient taking atorvastatin?

The correct answer is to monitor creatinine kinase in patients taking atorvastatin. Atorvastatin is a statin medication primarily used to lower cholesterol levels and reduce the risk of cardiovascular disease. One of the potential side effects of statin therapy is muscle-related issues, including myopathy and rhabdomyolysis, which can lead to an elevation of creatinine kinase (CK) levels in the blood.

Monitoring CK levels can help identify muscle damage early in patients receiving atorvastatin. An increase in CK may suggest muscle injury, prompting further investigation and potential adjustment of the statin therapy. This is particularly important for patients who may have risk factors for muscle toxicity, such as older age, concurrent use of other medications that affect muscle metabolism, or pre-existing conditions like kidney disease.

The other laboratory values listed are not routinely monitored in patients taking atorvastatin. Erythrocyte sedimentation rate is more related to inflammatory processes and does not provide specific information regarding the effects of atorvastatin. International normalized ratio (INR) is important for patients on anticoagulant therapy, particularly those taking warfarin, but it is not relevant for patients using atorvastatin. Monitoring potassium is vital in certain contexts, particularly in