Placental Growth Factor (PLGF)

Why this test? 

For early diagnosis of preeclampsia.

In what cases is it prescribed?

When examining pregnant women with risk factors for the development of preeclampsia (for example, age over 40 years, presence of insulin-dependent diabetes mellitus, smoking).

Test Information 

Preeclampsia is a complication of pregnancy, childbirth and the postpartum period, which manifests itself in the form of an increase in blood pressure and the level of protein in the urine.

According to the definition of the International Society for the Study of Hypertension in Pregnancy (ISSHP), preeclampsia is defined as an increase in blood pressure above 140/90 mm Hg. art., detected at two measurements with an interval of more than 4 hours, and the presence of proteinuria of more than 0.3 g in the daily urine (or more than 30 mg / mmol when using the protein-creatinine ratio), which occur de novo after the 20th week of pregnancy and completely disappear by the 6th week of the postpartum period. Preeclampsia complicates 2-8% of pregnancies. 

Although the severity of clinical manifestations varies greatly, the prognosis is usually favorable for the development of mild preeclampsia after the 36th week. On the contrary, the threat to the health of the mother or the fetus seriously increases if preeclampsia develops early (before the 33rd week) or at any time in the presence of concomitant diseases. 

It is believed that preeclampsia develops as a result of a violation of the process of differentiation and invasion of the trophoblast in the early stages of pregnancy. This leads to a number of pathological changes in the body of a pregnant woman, the most important of which are stimulation of oxidative stress and systemic inflammatory response, dysfunction of the endothelium of placental vessels, and systemic arterial hypertension. 

Several risk factors for preeclampsia have been identified: age over 40 years, obesity, family and personal history complicated by preeclampsia, antiphospholipid syndrome, insulin-dependent diabetes mellitus, multiple pregnancy and first birth, as well as arterial hypertension and kidney disease. 

Early detection of preeclampsia is the main step in the treatment of this condition. Recently, new laboratory tests have appeared, which can be used to suspect preeclampsia in the stages preceding the appearance of protein in the urine and an increase in blood pressure (pre-preeclampsia). 

One such test is the placental growth factor test. Placental growth factor (PGF) is one of the proteins of the vascular endothelial growth factor (VEGF) family. PFR is produced by the trophoblast and has a pronounced angiogenic potential. 

Angiogenesis is a key process in the development of the vascular system of the placenta. Normally, the concentration of PFR gradually increases until the 30th week of pregnancy. On the contrary, preeclampsia is characterized by a low concentration of PFR.

Moreover, it was found that a decrease in the concentration of PFR precedes the appearance of clinical signs of preeclampsia. In one of the studies, it was shown that a low level of PFR at 20-35 weeks is a sensitive marker of the development of preeclampsia in the next 2 weeks. It is believed that changes in PFR concentration are not the cause of pathological changes in the placenta, but arise in response to placental insufficiency. 

Some factors have a significant impact on the result of the PFR study: gestational age, weight and age of the mother, her ethnicity, smoking, conception through IVF, lack of childbirth in the anamnesis and diabetes. 

Therefore, before comparing the research result with the norm, the PFR concentration is adjusted taking into account these factors and expressed in units of MoM (from the English Multiple of the mean). MoM is the ratio of the concentration of a diagnostic marker (for example, PFR) of a given patient to the average concentration of this marker in the corresponding group of women (for example, women at the same stage of pregnancy). 

The same approach is used when evaluating the result of alpha-fetoprotein (AFP) in the diagnosis of fetal abnormalities. The PFR test can be supplemented with tests for other markers of preeclampsia, such as soluble fms-like tyrosine kinase-1 (sFlt-1) and pregnancy-associated plasma protein A (PAPP-A).