Low alkaline phosphatase is commonly seen in severe chronic nephritis, thyroid insufficiency in children, anemia, etc. Kidney function, thyroid function and blood tests can be done. 1. Definition of alkaline phosphatase: Alkaline phosphatase is widely distributed in human liver, bones, intestines, kidneys and placenta and other tissues, and it is an enzyme that is excreted out of the bile through the liver. Alkaline phosphatase is not a single enzyme, but a group of isoenzymes; six isoenzymes have been found, all of which belong to alkaline phosphatase; three of them are from the liver, one from bone cells, one from placenta and cancer cells, and one from the villous epithelium of small intestine and fibroblasts. 2. Measurement significance of alkaline phosphatase: Clinical measurement of alkaline phosphatase is mainly used for the diagnosis and differential diagnosis of bone, hepatobiliary system diseases, especially the differential diagnosis of jaundice. For unexplained high alkaline phosphatase serum level, isoenzymes can be measured to assist in clarifying its organ origin. 3. Low alkaline phosphatase: Low alkaline phosphatase is common in the following conditions: (1) Severe chronic nephritis: this disease leads to a decrease in the synthesis and production of alkaline phosphatase by the kidneys, which can be detected by renal function tests, including serum creatinine measurement and serum urea nitrogen measurement. (2) Thyroid insufficiency in children: this disease can also lead to a decrease in alkaline phosphatase synthesis, which can be detected by thyroid function tests. (3) Anemia: Some people with anemia may also show a decrease in alkaline phosphatase, which can be detected by routine blood tests. When alkaline phosphatase is found to be low, it should be further diagnosed and treated by a medical professional.