In enzymatic methods for measuring serum triglycerides, which substance is hydrolyzed from triglyceride to initiate the assay?

• A. phospholipids
• B. glycerol
• C. fatty acids
• D. pre-beta lipoprotein

Answer: (B)

The essential concept is that enzymatic triglyceride assays start with the lipase-driven hydrolysis of triglyceride to glycerol and fatty acids, and the detection chemistry is built around the glycerol produced. After triglyceride is broken down, glycerol is the substrate that enters the glycerol kinase–mediated pathway, where glycerol is phosphorylated to glycerol-3-phosphate, then oxidized to generate hydrogen peroxide that drives the colorimetric signal. Because each triglyceride molecule yields one glycerol molecule upon complete hydrolysis, measuring the amount of glycerol directly reflects the triglyceride level. The other substances—phospholipids, fatty acids, or pre-beta lipoprotein—aren’t the substrate for the detection step, so they don’t initiate the assay’s measurable reaction in this enzymatic method.