RUDN University doctors named the causes of a dangerous syndrome during pregnancy

Atypical hemolytic uremic syndrome (aHUS) is a disease in which blood clots form in small blood vessels. This leads to organ damage and multiple organ failure. The syndrome occurs rarely, but the prognosis of its outcome is usually unfavorable. It was previously thought that pregnancy provoked atypical hemolytic uremic syndrome, but more recently, scientists have suggested that this is due to pregnancy-related complications.

“Pregnancy-related atypical hemolytic uremic syndrome is a very rare but life-threatening disorder associated with poor patient outcomes. Historically, pregnancy has been considered as one of the important triggers of aHUS. However, recent studies show that pregnancy complications such as eclampsia (critically high blood pressure) and HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count), as well as pregnancy-related surgery (eg, caesarean section), and not pregnancy as such, may be conditions predisposing to the development of aHUS," - PhD Ksenia Demyanova, assistant of the Department of Internal Diseases with a course of cardiology and functional diagnostics named after Academician V.S. Moiseeva RUDN.

RUDN University doctors have shown that aHUS can be triggered by conditions that cause the activation of the complement system, a complex of protective proteins that are involved in the body's immune response.

The doctors examined the data of 75 pregnant patients diagnosed with aHUS, who applied to perinatal centers from 2011 to 2021. All during pregnancy or 42 days after birth were found to have thrombotic microangiopathy - systemic thrombosis of the kidney vessels. The majority (72 of 75) developed aHUS within eight days of delivery. RUDN University physicians have studied the genes responsible for the proteins of the complement system. The most common activator of the complement system was preeclampsia, a complex condition characterized by arterial hypertension, edema, proteinuria (impaired urine composition), and multiple organ failure. In 17 patients, one or another factor affecting the activation of the complement complex was encountered - caesarean section, infections, bleeding, etc. At the same time, doctors did not find any relationship with age or the number of pregnancies.

“Uncontrolled activation of the complement system can be caused by various combinations of conditions. However, it is still unknown how many of these conditions are necessary for the development of aHUS in an individual. The risk of aHUS appears to be higher in patients with preeclampsia, which causes many other obstetric complications such as placental abruption, fetal death, and bleeding, and often requires a caesarean section. Further research is needed to better understand the mechanisms of aHUS and its triggers,” Natalya Kozlovskaya, Doctor of Medical Sciences, Professor of the Department of Internal Medicine with a course of cardiology and functional diagnostics named after academician V. S. Moiseev, RUDN University.

The results are published in the Clinical Kidney Journal.