An increase in which serum lab value indicates to the nurse that a prescription for atorvastatin is having the desired effect for a client at risk for coronary artery disease?

A. Low-density lipoprotein (LDL): Atorvastatin's primary effect is to decrease LDL cholesterol levels. A decrease in LDL levels would indicate the medication is working as intended, not an increase. B. Prothrombin time (PT): PT is a measure of blood clotting, which is not directly affected by atorvastatin. This value is more relevant for monitoring anticoagulant therapy. C. Creatine phosphokinase (CK): CK levels can be used to monitor for muscle damage or side effects related to statin use. An increase in CK levels would suggest muscle damage, not the effectiveness of the statin. D. High-density lipoprotein (HDL): Atorvastatin is a statin medication used to lower cholesterol levels, particularly low-density lipoprotein (LDL) cholesterol, which is a key target in reducing the risk of coronary artery disease (CAD). While the primary goal of atorvastatin is to lower LDL cholesterol, an increase in HDL cholesterol (often termed "good" cholesterol) is also desirable as it can help reduce the risk of CAD. Therefore, an increase in HDL is a positive indicator that the medication is having a beneficial effect.