Carobohydrate antigen CA 19-9 in the blood
Last reviewed: 23.04.2024
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The reference values (norm) CA 19-9 in the blood serum - up to 37 IU / ml. Half-life is 5 days.
CA 19-9 is a glycoprotein found in the fetal epithelium of the pancreas, stomach, liver, small and large intestine, lungs. In adults, this antigen is a marker of the glandular epithelium of most internal organs and a product of their secretion. It should be borne in mind that the antigenic determinant of the CA 19-9 antigen and the Ar of the Lewis blood group (Le (ab-)) is encoded by one gene, which is absent in 7-10% of the population in the population.Thus, this number of people genetically lacks the ability to synthesize CA 19- 9, therefore, even in the presence of a malignant tumor from the glandular epithelium, the level of the marker in serum is not determined or its concentration is at very low values. CA 19-9 is excreted exclusively with bile, so even insignificant cholestasis can cause significant (in 50% of cases of pancreatitis) and liver (hepatitis, cirrhosis) and also in cases of high blood pressure, , in cystic fibrosis and inflammatory diseases of the pelvic organs in women (in 25% of cases of endometriosis and uterine myoma) .In these groups of patients, CA 19-9 can be used as a marker for monitoring the treatment of these diseases.
As a marker of pancreatic carcinoma CA 19-9 has a sensitivity of 82%. No correlation was found between the concentration of the marker and the mass of the tumor. However, its level above 10 000 IU / ml indicates the presence of distant metastases. The study of the level of CA-19-9 in dynamics provides valuable information for assessing the effectiveness of surgical treatment and determining the prognosis. With a low level of CA-19-9 in the blood (64-690 IU / ml), life expectancy averages 17 months, with a level of 75-24 000 IU / ml - 4 months. CA 19-9 has a sensitivity of 50-75% for hepatobiliary carcinoma. Currently, CA 19-9 is the second most important marker (after CEA) for the diagnosis of gastric carcinoma. Its increase is observed in 42-62% of patients with stomach cancer. The sensitivity of CA 19-9 is:
- in patients with pancreatic cancer - 82% at a separation point of more than 80 IU / ml;
- in patients with liver cancer - 76% at a separation point of more than 80 IU / ml;
- in patients with gastric cancer - 29% at a separation point of more than 100 IU / ml;
- in patients with colorectal cancer - 25% at a separation point of more than 80 IU / ml.
Determination of the content of CA 19-9 in serum is used:
- for diagnosis and monitoring of pancreatic cancer treatment;
- for early detection of metastasis of a pancreatic tumor;
- for monitoring cancer of the colon, stomach, gallbladder and bile ducts;
- for diagnosis and monitoring of treatment of ovarian cancer (in combination with CA-125 and CA 72-4).
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