A 60-year-old smoker with weight loss is found to have isolated elevation of alkaline phosphatase. Electrophoresis reveals an abnormal band that is strongly heat stable at 65 degrees Celsius and immunochemically identical to placental alkaline phosphatase. This isoenzyme is known as:
- A Regan isoenzyme ✓
- B Nagao isoenzyme
- C Kasahara isoenzyme
- D Bone-type alkaline phosphatase variant
Correct answer: A. Regan isoenzyme
Explanation
The Regan isoenzyme is a tumour-derived alkaline phosphatase that is biochemically and immunologically identical to the placental isoenzyme and shares its marked heat stability at 65 degrees Celsius. It was first described in bronchogenic carcinoma. The Nagao isoenzyme is a related variant seen in some cancers, while Kasahara is a fetal intestinal type described in hepatoma. Bone alkaline phosphatase is heat labile and would not match this profile.
Reference: Harper's Illustrated Biochemistry, 31st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.