Placental lactogen in the blood

Reference values (norm) of placental lactogen concentration: in men and non-pregnant women there is no serum; at pregnancy 5-38 weeks - 0,5-11 mkg / ml (23-509 nmol / l).

Placental lactogen or placental somatomamotropin is a glycoprotein with a molecular mass of approximately 19,000. It is synthesized by syncytiotrophoblast from the early stages of pregnancy, while its content in the blood during physiologic pregnancy increases. The maximum concentration of placental lactogen is recorded at the 36-37th week of pregnancy, then it stabilizes, and before delivery decreases. The concentration of placental lactogen is very variable, individual and is directly dependent on the weight of the fetus and the amount of placenta (with multiple fetuses). Placental lactogen enters the body of a pregnant woman, where it is quickly metabolized (half-life - from 11 to 30 minutes). A short half-life, the absence of a daily rhythm of secretion and the presence of a single source of its synthesis make it possible to use it as a direct indicator of the functioning of the placenta. Placental lactogen practically does not penetrate to the fetus, in the amniotic fluid its level is 8-10 times lower than in the pregnant woman's blood. In its properties, it is similar to growth hormone, but in pregnancy its production exceeds 100 times the secretion of growth hormone. Placental lactogen stimulates the mobilization of fatty acids, has a lactotropic and luteotropic effect, inhibits cellular immunity, actively influences metabolism (promotes glucose consumption in the fetus, reduces protein synthesis in the pregnant woman, which substantially increases the supply of amino acids that the fetus uses for its formation) . Placental lactogen is also an insulin antagonist, plays an important role in the maturation and development of mammary glands during pregnancy and in their preparation for lactation. In addition, like prolactin, it supports the work of the yellow body of the ovaries during pregnancy, promotes increased secretion of the yellow body of progesterone.

In the first trimester of pregnancy with the development of placental insufficiency, the level of placental lactogen is significantly reduced. Extremely low values of its concentration in the blood are revealed on the eve of the fetal death and 1-3 days before the spontaneous miscarriage. In later periods of pregnancy, a decrease in the concentration of placental lactogen is detected with placental insufficiency and chronic fetal hypoxia. However, its content in the blood varies widely, but most pregnant women are significantly below normal. With placental insufficiency, the content of placental lactogen in the blood serum is reduced by 50%, and with hypoxia of the fetus - almost 3 times. The concentration of placental lactogen decreases with hypertension, late gestosis. Indications for the study of placental lactogen: diagnosis of placental insufficiency, hypoxia and fetal hypotrophy.

Elevated concentrations of placental lactogen in the blood are observed in multiple pregnancies, diabetes mellitus; rhesus incompatibility. Placental lactogen is also produced by the trophoblastic tumor. The greater the degree of malignancy, the lower the ratio of the levels of placental lactogen and chorionic gonadotropin.

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