Background
- Group of isoenzymes that catalyzes hydrolysis of organic phosphate esters in the extracellular space
- Found in liver, bone, placenta, ileal mucosa, and kidney
- Can be tissue-specific or tissue-nonspecific, the latter of which makes up most of the serum ALP
Interpretation
- Serum marker from biliary tract, bone, and placenta
- In bone, it indicates high bone turnover, which can be from a number of causes: healing fractures, osteomalacia, hyperparathyroidism, hyperthyroidism, Paget disease of bone, osteogenic sarcoma, and bone metastases
- Hemolysis, jaundice, and high lipids can interfere with testing
- Many things affect serum ALP
Isoenzymes
- Electrophoresis can separate into liver, bone, placental, and intestinal fractions
- Liver and bone are hard to separate
