A 60-year-old woman has serum alkaline phosphatase of 420 U/L. To determine whether the source is hepatobiliary rather than skeletal, which additional enzyme should be measured?
- A 5'-Nucleotidase ✓
- B Lactate dehydrogenase
- C Acid phosphatase
- D Amylase
Correct answer: A. 5'-Nucleotidase
Explanation
5'-Nucleotidase is a canalicular membrane enzyme whose behavior mirrors alkaline phosphatase in hepatobiliary disease: it rises in cholestasis and infiltrative liver disorders but remains normal in pure bone disease such as Paget disease or growing children. C parallel elevation of 5'-nucleotidase with ALP therefore localizes the source to the liver. Acid phosphatase marks prostate, and LDH is too nonspecific to separate bone from liver.
Reference: Harper's Illustrated Biochemistry, 31st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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