Which enzyme is measured in whole blood?

Glucose-6-phosphate dehydrogenase (G6PD) is the correct answer because it is an enzyme that is typically measured in whole blood for diagnosing conditions such as G6PD deficiency. G6PD plays a vital role in the pentose phosphate pathway, which is essential for producing NADPH necessary for cellular processes and maintenance of cell integrity, especially in red blood cells. When G6PD levels are low, it can lead to hemolytic anemia due to oxidative stress, which is particularly relevant in certain populations.

The other enzymes listed are not primarily measured in whole blood. Chymotrypsin, for example, is mainly measured in other biological fluids like serum or pancreatic secretions and is involved in protein digestion. Glycogen phosphorylase is primarily measured in tissues like the liver and muscle rather than whole blood and is important in glycogen metabolism. Lipase is closely associated with the diagnosis of pancreatic diseases and is typically measured in serum rather than whole blood. This context establishes the importance of G6PD measurement in whole blood, making it crucial for diagnosing specific hematological conditions.