Alkaline phosphatase is produced by which tissues?

Alkaline phosphatase is produced by which tissues?

• A. Liver
• B. Bone
• C. Placenta
• D. All of the above

Answer: (D)

Alkaline phosphatase comes from several tissues that actively express this enzyme. It is produced by osteoblasts in bone, where it helps mineralization by supplying phosphate for hydroxyapatite formation. It is also produced by liver cells and bile duct epithelium, with levels rising in conditions affecting bile flow or liver function. Additionally, the placenta—specifically the syncytiotrophoblasts—secretes ALP during pregnancy. Because each of these tissues contributes to the circulating alkaline phosphatase pool, the correct answer is all of the above. (There is also intestinal ALP, which isn’t listed here.)

Alkaline phosphatase comes from several tissues that actively express this enzyme. It is produced by osteoblasts in bone, where it helps mineralization by supplying phosphate for hydroxyapatite formation. It is also produced by liver cells and bile duct epithelium, with levels rising in conditions affecting bile flow or liver function. Additionally, the placenta—specifically the syncytiotrophoblasts—secretes ALP during pregnancy. Because each of these tissues contributes to the circulating alkaline phosphatase pool, the correct answer is all of the above. (There is also intestinal ALP, which isn’t listed here.)