Low alkaline phosphatase levels in patients with lupus can occur due to various causes. Commonly, medications, malnutrition, zinc & magnesium deficiency, hypothyroidism, severe anemia associated with lupus, and others.
The main causes of marked elevations in alkaline phosphatase include biliary obstruction, liver diseases such as primary biliary cholangitis, transient hyperphosphatasemia in infancy and early childhood, liver transplant rejection, and others.
A slightly elevated alkaline phosphatase level is caused by either physiological conditions (such as pregnancy, growing bones, or aging). It is also caused by disease conditions such as liver, biliary, bone, thyroid diseases, some cancers, etc.