Alkaline phosphatase (ALP) is an enzyme present in all human tissues throughout the body. The bulk of it, however, is found in the liver, where most of it is produced. A blood test for ALP can reveal different conditions when the enzyme is either higher or lower than the normal range. High ALP indicates spurts of bone growth. These can be normal and healthy (e.g. at puberty or during pregnancy), or they can indicate pathological conditions of the skeletal system such as Paget’s disease or osteomalacia.
Low levels of ALP indicate a great variety of problems: malnutrition, hypothyroidism, scurvy, deficiency of the essential mineral nutrients zinc and magnesium, anemia, and others.
It can also indicate factors incident to menopause. There are also a few more serious conditions which can give rise to low alkaline phosphatase levels. In all cases, when a blood test indicates low alkaline phosphatase levels, further diagnostic procedures are indicated to discover the reason for the result and allow for appropriate treatment.
Malnutrition is the most common cause of low alkaline phosphatase. In particular, inadequate consumption of vitamin B6, folic acid, vitamin C, zinc, and magnesium are the most common nutritional causes, along with excess consumption of vitamin D. All of these can result from a poor, inadequately varied diet, although there are some medical conditions which interfere with the processing of certain vitamins and minerals which can have the same result.
Scurvy is a condition caused by prolonged vitamin C deficiency. Low alkaline phosphatase is one of the early indicators of this deficiency, which can lead to more serious symptoms later on if it continues (eventually being fatal).
Hypothyroidism is a condition in which the production of hormones by the thyroid glad is below normal. This condition can also result in low
ALP levels. Hypothyroidism tends to occur in older people, more commonly in women who are past menopause.
Anemia can result from causes that range from injury and loss of blood, to nutritional deficiency primarily in iron, to infections. Anemia can also cause low ALP levels.
Because ALP levels can be low due to a variety of different causes, further diagnostic work is normally required when this result shows in a blood test to determine the precise cause.
Treatment depends on the underlying cause of the low ALP levels. If the cause is a nutritional deficiency, as is most common, treatment consists of restoring normal and healthy dietary levels to correct the deficiency. However, this requires determining the specific nature of the deficiency, which can be discovered through further diagnostic testing or simply by examining the patient’s diet.
If the cause is hypothyroidism, the appropriate treatment is replacement of thyroid hormones with synthetics such as levothyroxine. As with nutritional deficiencies, further diagnostic work is required to eliminate other causes and determine that hypothyroidism is actually involved.
If the cause is a form of anemia, treatment will depend on the type of anemia present, but always consists of efforts to bring blood volume or red blood cell count (as appropriate) up to normal, healthy levels.
In almost all cases, the prognosis with low ALP levels is good. Nutritional deficiencies, which are the most common cause, are easily corrected and, unless they have progressed to severe stages, do not result in significant permanent harm. There are a few causes of the low ALP blood test result which have more guarded prognosis. These include aplastic anemia, chronic myelogenous lukemia, Wilson’s disease, achronodroplastia, and cretinism.