Patients often worry about abnormal lab test results, especially when the abnormal results raise the specter of cancer. You should not panic if you have elevated alkaline phosphatase levels, because this is relatively common. Your doctor may want to do additional blood tests, including one for alkaline phosphatase isozymes. There are different aklaline phosphase isozymes, each which has a slightly different chemical structure.
Normal Elevations
Elevated alkaline phosphatase levels are associated with both healthy and unhealthy bone growth. Examples of healthy bone growth that elevate alkaline phosphatase levels include pregnancy, growth spurts in children and the healing of a fractured bone.
Drug-related Reasons
Many common drugs cause alkaline phosphatase levels to become elevated. Patients take some of these drugs, such as birth control pills, allopurinol, methyldopa, arthritis and diabetes medications, for extended periods of time. Other drugs that elevate alkaline phosphatase include tranquilizers, tricyclic antidepressants and chlorpromazine, which are used to treat psychiatric disorders. If your alkaline phosphatase levels become elevated because of drug use, your doctor will consider whether to change treatment protocols.
Liver disease
Since alkaline phosphatase is concentrated in the liver where it breaks down drugs and other compounds, elevated levels can be indicative of liver disease. Liver diseases that elevate alkaline phosphatase include hepatitis, cirrhosis and liver cancer. If alkaline phosphatase levels are elevated because of liver disease, other liver enzymes, such as aspartate aminotransferase and alanine aminotransferase, are usually high as well.
Bone Disease
Bones diseases, such as rickets, osteoblastic bone cancers, osteomalacia and Paget's disease, also cause elevated alkaline phosphatase levels. In some instances, the doctor may request alkaline phosphatase isozyme tests, which provide more certainty as to the diagnosis. Isozymes associated with bone disease are different from isozymes associated with other diseases.
References
- MedlinePlus; ALP; June 2011
- Lab Tests Online: ALP
- Mayo Clinic; Liver Function Tests; July 2010
- "Bioscience Reports"; Chlorpromazine and Other Psychoactive Drug Induced Alterations of a Membrane Bound Enzyme in Rat Brain; M. Nag M and N. Nandi; June 1994
- MedlinePlus; ALP Isoenzyme Test; June 2011
- "European Journal of Cancer"; The Bone Isoenzyme of Alkaline Phosphatase in Hypercalcaemic Cancer Patients; J.J. Body, et al.; September 1997
