Which statement correctly describes alkaline phosphatase?

Which statement correctly describes alkaline phosphatase?

• A. Decreased in Paget disease
• B. Decreased in third trimester of a normal pregnancy
• C. Increased in obstructive jaundice
• D. Primarily found in cardiac muscle

Answer: (C)

Alkaline phosphatase is an enzyme mainly released from the liver/bile ducts and bone, with a placental form present during pregnancy. Its levels rise when bile flow is blocked (obstructive jaundice) because the biliary epithelium responds to cholestasis by increasing ALP production and releasing it into the blood. This makes increased ALP a characteristic finding in obstructive jaundice. Paget disease involves increased bone remodeling, which elevates ALP rather than decreasing it, so the statement about a decrease is incorrect. In the third trimester of normal pregnancy, placental ALP contributes to higher serum levels, not lower. And ALP is not primarily found in cardiac muscle; cardiac muscle damage markers are different (like CK-MB or troponin).

Alkaline phosphatase is an enzyme mainly released from the liver/bile ducts and bone, with a placental form present during pregnancy. Its levels rise when bile flow is blocked (obstructive jaundice) because the biliary epithelium responds to cholestasis by increasing ALP production and releasing it into the blood. This makes increased ALP a characteristic finding in obstructive jaundice.

Paget disease involves increased bone remodeling, which elevates ALP rather than decreasing it, so the statement about a decrease is incorrect. In the third trimester of normal pregnancy, placental ALP contributes to higher serum levels, not lower. And ALP is not primarily found in cardiac muscle; cardiac muscle damage markers are different (like CK-MB or troponin).