Increase and decrease in alkaline phosphatase

In children, alkaline phosphatase is increased until puberty. Increased activity of alkaline phosphatase accompanies rickets of any etiology, Paget's disease, bone changes associated with hyperparathyroidism. The activity of the enzyme rapidly increases with osteogenic sarcoma, metastases of cancer in the bone, myeloma, and lymphogranulomatosis with bone damage.

The activity of the hepatic form of phosphatase is most often increased due to damage or destruction of hepatocytes (liver-cell mechanism) or biliary transport disorders (cholestatic mechanism). The liver-cell mechanism of increasing the activity of alkaline phosphatase plays a leading role in viral and autoimmune hepatitis, toxic and medicinal liver damage. Outflow of bile is disrupted due to extrahepatic obstruction of the bile ducts (for example, by a stone or with the development of postoperative stricture), narrowing of the intrahepatic ducts (for example, with primary sclerosing cholangitis), damage to the bile ducts (for example, in primary biliary cirrhosis ) or biliary transport disorders at small bile ducts (with the use of a number of drugs, for example, chlorpromazine). In some cases, the activity of alkaline phosphatase increases due to the simultaneous action of both mechanisms of damage.

Increase in activity of alkaline phosphatase in liver damage occurs due to its release from hepatocytes. The activity of alkaline phosphatase in viral hepatitis, in contrast to aminotransferases, remains normal or increases slightly. An increase in the activity of alkaline phosphatase is found in icteric patients with cirrhosis of the liver (in a third of cases).

Approximately half of patients with infectious mononucleosis in the first week of the disease also notice an increase in activity of alkaline phosphatase. A significant increase in the activity of alkaline phosphatase is observed with cholestasis. The extrahepatic occlusion of the bile ducts is accompanied by a sharp increase in the activity of the enzyme.

An increase in the activity of alkaline phosphatase is observed in 90% of patients with primary liver cancer and with metastases to the liver. Sharply increases its activity in alcohol poisoning against the background of alcoholism. It can increase with the use of drugs that have a hepatotoxic effect (tetracycline, paracetamol, mercaptopurine, salicylates, etc.). Cholestatic jaundice and, accordingly, increased activity of alkaline phosphatase are possible in women taking oral contraceptives containing estrogens and progesterone. According to different authors, only about 65% of hospitalized patients have high activity of alkaline phosphatase due to liver diseases.

Very high activity of the enzyme is observed in women with preeclampsia, which is associated with placental lesions. Reduced activity of alkaline phosphatase in pregnant women may indicate a lack of development of the placenta.

In addition to the above reasons, the increase in activity of alkaline phosphatase is revealed in the following diseases and conditions: increased metabolism in bone tissue (with healing of fractures), primary and secondary hyperparathyroidism, osteomalacia, renal rickets, cytomegalovirus infection (CMV infection) in children, sepsis, ulcerative colitis , regional ileitis, intestinal bacterial infections, thyrotoxicosis. This is due to the fact that alkaline phosphatase is produced not only in the liver, but also in other organs - bones, intestines.

A number of values are multipliers multiplied by the value of the upper reference limit for alkaline phosphatase.

An increase in the level of this enzyme of hepatocytes suggests the presence of cholestasis. However, alkaline phosphatase consists of several isoenzymes and is contained in various tissues, in particular in the bone.

An increase in the level of alkaline phosphatase in 4 times and more occurs 1-2 days after the development of biliary obstruction, regardless of its level. The level of the enzyme may remain elevated for several days after the removal of obstruction, since the half-life of alkaline phosphatase is approximately 7 days. An increase in the enzyme level by 3 times is observed with various violations of the liver function, including hepatitis, cirrhosis of the liver, volumetric liver formations and infiltrative lesions. Isolated increases in the level of the enzyme (i.e., when other results of liver tests are within normal limits) occur frequently in focal liver lesions (eg, abscess, tumor) or partial or intermittent obstruction of the biliary tract. Isolated enhancements also occur in the absence of liver disease or the biliary tract, for example, when malignancy is not involved in the liver process (for example, bronchogenic cancer, Hodgkin's lymphoma, renal cell carcinoma), after eating fatty foods (the enzyme is formed in the small intestine), in pregnancy (in placenta), in children and adolescents during growth (due to bone growth) and chronic renal failure (in the intestine and bone tissue). Fractionation of alkaline phosphatase is technically difficult. Increasing the level of enzymes more specific for the liver, namely 5'-nucleotidase or gamma-glutamyltranspeptidase (GGT), allows differentiation of the hepatic or extrahepatic source of alkaline phosphatase. Isolated increases in alkaline phosphatase in asymptomatic cases in the elderly are usually associated with bone skeletal disorders (eg, Paget's disease) and do not require further investigation.

Reduction of alkaline phosphatase activity is noted in hypothyroidism, scurvy, severe anemia, kwashiorkor, hypophosphatemia.

[1], [2], [3], [4], [5], [6], [7]