Persistently Low Serum Alkaline Phosphatase

Important conditions to identify:

(1) hereditary hypophosphatasia (due to inactivating mutations of the ALPL gene for non-tissue specific alkaline phosphatase)

(2) Wilson's disease (especially with severe liver disease and hemolytic anemia)

(3) achondroplasia

(4) hypothyroidism

A low serum alkaline phosphatase can be seen in the following conditions if they remain untreated or unresolved:

Nutritional or gastrointestinal disorders:

(1) hypophosphatemia

(2) acquired zinc or magnesium deficiency

(3) scurvy

(4) kwashiorkor/malnutrition

(5) vitamin B12 deficiency, including pernicious anemia

(6) celiac disease

(7) milk-alkali syndrome

Drugs:

(1) oral contraceptives

(2) estrogens

(3) azathioprine

(4) clofibrate

(5) trifluoperazine

(6) corticosteroids

(7) vitamin D excess

Other:

(1) severe anemia