Which laboratory change indicates a therapeutic response to an antihyperlipidemic medication?

• A. Decreased high density lipoprotein (HDL) cholesterol
• B. Increased triglyceride level
• C. Decreased low density lipoprotein (LDL) cholesterol
• D. Increased bilirubin level

Answer: (C)

Lowering LDL cholesterol is the main measure of response to antihyperlipidemic therapy. These medications aim to reduce the amount of atherogenic LDL particles in the blood, and a decrease in LDL-C on a lipid panel reflects that beneficial effect and is closely linked to reduced cardiovascular risk.

HDL is the protective lipoprotein, and therapies do not rely on decreasing it to indicate success; a lower HDL would not signal a positive response. Triglycerides may change with some treatments, but they are not the primary/most reliable marker of efficacy for most antihyperlipidemics. An increase in bilirubin would point to possible liver injury, not a therapeutic benefit.

So, the lab change that best signals a therapeutic response is a decrease in LDL cholesterol.