Blood Test May Predict Preeclampsia
Protein Implicated in Life-Threatening Complication of Pregnancy
Feb. 5, 2004 -- There's a major new development in predicting preeclampsia, a life-threatening condition that occurs in about one of every 20 pregnancies: Researchers say that before symptoms emerge, testing levels of two molecules in the blood can indicate which women will get the disease that results in some 76,000 deaths each year.
In a new study, Harvard and NIH researchers say they detected abnormal levels of two substances in women who went on to develop preeclampsia weeks before telltale symptoms: Elevated levels of a protein called soluble fms-like tyrosine kinase 1 (sFlt-1) and decreased amounts of another substance known as placental growth factor (PlGF). However, no such fluctuations occurred in women whose pregnancies remained normal.
The changing levels of these substances -- which were noted to occur five to six weeks before any symptoms became apparent -- are believed to cause a cascade of effects "that eventually impairs blood vessel growth in the placenta, as well as the mother's kidneys, liver, and possibly the brain," says lead researcher S. Ananth Karumanchi, MD, of Harvard's Beth Israel Deaconess Medical Center.
Danger to Baby and Mother
Preeclampsia affects some 200,000 American women each year and is the leading cause of pregnancy-related death and a major contributor to premature birth. This condition is primarily characterized by an increase in blood pressure that occurs after 20 weeks of pregnancy in a woman with previously normal blood pressure. These women also have lots of protein in the urine -- a sign of kidney damage. Swelling, sudden weight gain, headaches, and vision changes may also occur.
The condition can also lead to seizures in pregnant women -- a condition known as eclampsia. It can slow fetal growth, force premature delivery, and cause severe bleeding and death of the fetus and possibly the mother.
Until now, doctors have been hard-pressed in predicting which women will develop preeclampsia in pregnancy, dubbed "the disease of theories" because despite many theories of its origin, its exact cause has eluded experts. Typically, risk is assessed on factors such as existing diabetes, high blood pressure, being overweight, being age 35 or older, being of African-American race, and having a history of multiple births or previous preeclampsia.
But with these new findings, Karumanchi says a diagnostic test to measure these protein levels can be developed -- as soon as within one year -- that can give doctors' a clue to who is likely to develop the condition.
"Pharmaceutical houses are now actively working on a diagnostic test, which still needs FDA approval," he tells WebMD. "Once we have identified in who the disease will happen, patients can be monitored more closely with bed rest, blood pressure medications, and other therapies. That way, we can better deal with the mother and baby before this disease explodes."
Until then, blood levels of these proteins can be evaluated at certain labs -- a process that takes about two hours.