Alkaline phosphatase is an enzyme present in several organs of your body, including bones, liver, kidney, intestines and, in pregnant women, the placenta. The highest concentration of this enzyme occurs in the liver and bones. Each of these tissues produces its own type of alkaline phosphatase. Doctors can measure alkaline phosphatase levels in the bloodstream and use them to diagnose bone disease.
Background
In your liver, alkaline phosphatase is present in the bile ducts, the tubes that transport bile into the intestines to help in digestion. In bone, cells called osteoblasts produce alkaline phosphatase during the formation of bone. According to Lab Tests Online, bone or liver damage, either by infection or inflammation, releases large amount of alkaline phosphatase into the bloodstream.
Paget's Disease
Paget's disease of the bone is a condition of excessive bone formation and destruction. The normal cycle of old bone being replaced by new bone breaks down in Paget's disease, resulting in malformed, fragile bones that break easily. According to the Mayo Clinic, the symptoms of Paget's disease include bone pain and weakness, bone deformities in the spine and skull, headache and tingling in the extremities. Alkaline phosphatase levels become elevated as a result of the rapid turnover of bone.
Rickets
Rickets is a condition that results from a deficiency of vitamin D in your diet. Vitamin D is important in the absorption of calcium and phosphate from your gut. These minerals are the building blocks of bone. If you develop rickets, your bones become soft and weak, and you may experience muscle weakness and bowing of the legs. Children with rickets display decreased bone growth. As your body tries to increase the levels of calcium in your bloodstream, it breaks down bone, resulting in an increase in the alkaline phosphatase level.
Bone Tumors
Bone tumors can be primary cancers, which originate within bone cells, or metastatic tumors, which originate in another organ of your body. The most common symptom of bone cancer is pain, although some cancers remain undetected until the bone becomes so weak that it fractures. According to the National Cancer Institute, alkaline phosphatase levels become elevated in bone cancers because bone tumors increase the production of abnormal bone tissue.
