Protein In Urine: Predicting Preelampsia
While women with preeclampsia, a serious condition specific to pregnancy, are known to have protein in their urine, estimating levels of this protein doesn't really say much about the possible outcomes, negative or positive, for mother or baby. Now, researchers have published a report in the journal known as BMC Medicine which includes data that may change the way clinicians assess patients with preeclampsia.
Preeclampsia, or toxemia, typically develops after the 20th week of pregnancy and is characterized by high blood pressure, edema and protein in the urine. However, when the condition becomes severe it can, without warning, escalate to eclampsia. This is a condition in which a massive rise in blood pressure causes the mother to suffer a series of potentially fatal complications and forces premature delivery of the baby. Blood vessels constrict and a reduced blood flow can affect organs such as the liver, kidneys and brain of the mother. The problems the baby will suffer due to decreased blood flow to the uterus include poor growth, too little amniotic fluid and placental abruption, where the placenta separates from the uterine wall before delivery. Additionally, the baby may suffer the negative effects of prematurity should the need to delivery early be necessary.
The changes in blood vessels that result from preeclampsia cause the capillaries to leak fluid into the tissues resulting in edema. When the blood vessels in the kidneys begin to leak, protein from the blood spills into the urine. That is the basic reason why urine tests have been used to determine preeclampsia.
Proteinuria, or protein in the urine, has long been considered the standard criterion for determining the presence of preeclampsia. Its presence and the degree to which it is present had been thought, until now, to give some indication of the degree of risk for potential negative outcomes for both the expectant mother and her fetus. But a current and thorough analysis of 16 research studies which include a total of 6749 women, has now determined that protein in the urine is not a sound method for predicting potential maternal or fetal complications. Included among the potential complications were a newborn's admission to a neonatal intensive care unit (NICU), babies born small for their gestational age, perinatal or neonatal deaths, stillbirths, placental abruption, eclampsia, and HELLP syndrome.
Birmingham Women's Hospital's Shakila Thangaratinam and her team of researchers employed the use of four medical databases, MEDLINE, MEDION, EMBASE, and the Cochrane Library to search for studies they might use in a systemized review. The research team began by calculating the number of positive and negative test results and then attempted to match up maternal and fetal outcomes with these clinical results. They hoped to determine the clinical pertinence of protein in the urine and its levels during preeclampsia for each chosen outcome.
Instead, the researchers discovered almost no correlation between proteinuria and its levels and these various outcomes except for a very slight elevation in the number of stillbirths where proteinuria levels reached 5g in 24 hours. In general, the researchers found that the presence of protein in the urine and the levels thereof were poor predictors for fetal outcomes such as neonatal or perinatal deaths, for instance.
Thangaratinam reported, "Our systematic review has shown proteinuria levels in preeclampsia to be poor predictors of adverse maternal and fetal outcomes. We need large well-conducted studies to estimate the risk of complications especially in the subgroup of women who have pre eclampsia before 34 weeks when the management decision is often critical to mother and baby."