Elevated Alkaline Phosphatase? What can that mean?

Alkaline phosphatase (ALP or ALK PHOS) is a blood marker found in a Complete Metabolic Panel. Commonly thought of as a liver marker, it is actually a group of isoenzymes that originate in bone, liver, intestines, skin and the placenta. It has a  maximal activity at a pH of 9-10.0, hence the name alkaline phosphatase. The “ase” gives us the clue that these are enzymes. Decreased blood levels of ALK can occur with severe zinc and/or magnesium deficiency.  Increase in ALK may be found in the below conditions:

Screen Shot 2024 12 26 at 9.15.54 PM

Biliary Obstruction

An increase in ALK is commonly seen in biliary obstruction where one may also see increased levels of bilirubin and GGT. Bile obstruction can be caused by a number of factors, but differential diagnosis should include bile stones, liver stones, biliary cancer and pancreatic cancer.

Liver Dysfunction due to Drug Toxicities

An increase in ALK can be an indicator of dysfunction due to drug toxicity. Try to correlate medication usage, both over-the-counter as well as prescription, to lab elevation. One would often see elevations of AST and ALT if toxicity is suspected. Drugs that commonly increase ALK may include Allopurinol, Colchicine, certain antibiotics, Fluorides, Verapamil, and Nicotinic acid

Liver Metastasis

Those with a known cancer diagnosis may experience elevations of ALK should the cancer metastasize to the liver itself. Primary carcinoma of the liver may also reveal an elevated ALK. One would often see elevations of AST and ALT in both primary and secondary cancer in the liver.

Bone Metastasis or other Bone Disorder

Since ALK is also found in bone, boney destruction will liberate ALK into the blood. Metastatic cancer to the bone is lytic, causing destruction of bone. Should this be the cause of elevated ALK, one may often see slight elevation of blood Calcium levels as well. Elevation of ALK due to bone involvement will spare other liver markers, i.e. AST and ALT may be normal.

Other Diseases of the Bone

Other disorders may elevate ALK such as Osteomalacia, Rickets, Paget’s disease, Rheumatoid arthritis (in later stages), and Hodgkin’s Lymphoma.

Bone Growth or Healing

ALK level may be elevated in normal bone growth and repair, as in boney healing post-trauma.

Shingles (Herpes Zoster)

Shingles has also been known to increase ALK levels, along with elevated sedimentation rate, C-reactive protein, total WBC, and basophil counts. Shingles spares ALT.