Alkaline phosphatase is an enzyme, or a protein that the cells use to make a biochemical reaction go at a faster pace. The normal range of alkaline phosphatase for a child is 40 to 400 IU/L. The level can rise as a result of normal metabolic reactions or as a result of several disorders. There are several conditions associated with a low level.
Alkaline Phosphatase
The enzyme alkaline phosphatase is primarily in the liver, intestines, kidneys, bones and placenta. The level of the enzyme increases when the cells increase their metabolism; that is, when they are having more biochemical reactions. It may also increase due to diseases that cause the enzyme to be released into the bloodstream. The level may be low because of hypothyroidism, Wilson's disease, malnutrition, pernicious anemia, the consumption of too much vitamin D, hypophosphatasia or a zinc deficiency, according to Leonard Gomella, M.D., in the "Clinician's Pocket Reference."
Hypophosphatasia
Hypophosphatasia is the name of a rare hereditary disorder where the low amount of alkaline phosphatase results in weak, soft bones. There are actually six different types, as explained in "Current Diagnosis & Treatment: Pediatrics" by Philip Zeitler, M.D., Ph.D. Some infants may have such severe skeletal abnormalities that they live but just a few days. Other children may have abnormalities in the cranium bone in the skull, or may prematurely lose their teeth.
Hypothyroidism
Children with hypothyroidism may have a low alkaline phosphatase level, a disorder that occurs in approximately one out of every 4,000 newborns, per J. Larry Jameson, M.D., Ph.D., in "Harrison's Principles of Internal Medicine." Most of them are hypothyroid because their thyroid gland did not develop, and it is the thyroid gland that makes and releases the thyroid hormone. The majority look healthy when they are born, but because they will have permanent damage to the nervous system if they are not treated, all newborns are screened for thyroid hormone levels.
Wilson's Disease and Pernicious Anemia
Wilson's disease, also called hepaticolenticular degeneration, is another rare hereditary disease. It develops in children who do not have enough of a protein needed to carry copper within the blood. As a result, copper is deposited in the eyes, brain, liver and kidneys. As explained by the University of Maryland Medical Center, the copper deposits damage the tissues. A lab test may also find a low alkaline phosphatase level in pernicious anemia. In this disorder, the parietal cells of the stomach cannot secrete intrinsic factor, a protein that the small intestines must have to absorb vitamin B12.
References
- "Clinician's Pocket Reference"; Leonard Gomella, M.D. and Steven Haist, M.D.; 2007
- "Current Diagnosis & Treatment: Pediatrics"; William Hay, Jr., M.D., Myron Levin, M.D., et al.; 2011
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, M.D., Dennis Kasper, M.D., et al.; 2008
- University of Maryland Medical Center; Wilson's Disease -- Overview; Diana Chambers; 2008
- University of Maryland Medical Center; ALP -- Overview; David Dugdale, III, M.D.; 2009
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