Alkaline Phosphatase

What is Alkaline Phosphatase?

Alkaline phosphatase (ALP) is an enzyme found on the surface of cells lining the bile ducts (liver), osteoblasts (bone), intestinal epithelium, placenta, and kidneys. It catalyzes the hydrolysis of phosphate esters in alkaline environments. Serum ALP is primarily a mixture of liver and bone isoenzymes.

What might a high or low Alkaline Phosphatase mean?

Raised ALP is associated with either liver/bile-duct conditions or increased bone turnover — the usual question is the source. In adults, raised ALP with a raised GGT points to a liver origin; raised ALP with a normal GGT points more to bone. ALP is also a PhenoAge biomarker.

What is the typical reference range for Alkaline Phosphatase?

The general-population reference range shown here is 40 – 129 U/L. Reference ranges describe the general population and are not a personal target — discuss your results with your physician.

What can affect Alkaline Phosphatase?

It may be higher with: Bile duct obstruction (gallstones, tumors), Cholestatic liver disease, Bone disease (Paget's, osteomalacia), Bone fracture healing, Pregnancy (placental ALP), Growth in children/adolescents, Hyperparathyroidism, Vitamin D deficiency (secondary hyperPTH). It may be lower with: Zinc deficiency (ALP is zinc-dependent), Hypothyroidism, Pernicious anemia, Malnutrition, Celiac disease, Cardiac surgery (transient).