Pre-eclampsia, a condition characterized by high blood pressure, protein in the urine and fluid retention can lead to some of the potentially deadliest side effects in pregnancy. Pre-eclampsia, also called pregnancy-induced hypertension or toxemia, develops after the 20th week of pregnancy. Between 5 to 8 percent of women develop pre-eclampsia in pregnancy, according to Jeff Hollingsworth, M.D., of the University of North Carolina Chapel Hill. Severe pre-eclampsia can cause acute renal failure as one of its complications. Treatment with magnesium sulfate helps prevent seizures, another serious complication of pre-eclampsia.
Symptoms
Pre-eclampsia does not always cause severe symptoms. But once severe pre-eclampsia develops, you may have decreased urine output, severe headaches, abdominal pain in the upper outer quadrant, agitation, nausea, vomiting, or vision changes, such as blurred vision, spots before your eyes or light sensitivity. Liver enzymes may be elevated and platelet levels lower than normal. You may gain a large amount of weight very quickly. Fluid in the lungs, called pulmonary edema, and signs of acute renal failure or seizures indicate a need for immediate delivery of your baby. Acute renal failure is rare in pre-eclampsia unless severe disseminated intravascular coagulopathy, also called DIC, develops, notes nephrologist Amelia R. Bernasconi, M.D., of Hospital J. A. Fernandez in Argentina.
Magnesium Sulfate Actions
Magnesium sulfate acts to prevent seizures caused by pre-eclampsia. Magnesium sulfate is usually given intravenously; anticonvulsant effects start immediately and last about 30 minutes. Continuous infusions prevent seizures and help lower elevated blood pressure by dilating blood vessels. Therapeutic levels of magnesium during treatment range from 2.5 or 3.0 to 7.5 mEq/liter.
Magnesium Sulfate and Kidney Effects
Because magnesium sulfate is excreted entirely through the kidneys, acute kidney failure can decrease excretion of the drug, resulting in possible magnesium toxicity. Signs of magnesium toxicity include loss of deep tendon reflexes, which start to decrease at magnesium levels over 4 mEq/L; slowed respiration, flushing, sweating, nausea, low body temperature, muscle weakness, low blood temperature and circulatory collapse may also occur. Respiratory paralysis can occur when magnesium levels reach 10mEq/L.
Long-Term Complications
Delivery of the baby is the only sure cure for pre-eclampsia. Recovery normally takes place gradually over the first six weeks after delivery. However, a Norwegian study published in the August 2008 issue of the "New England Journal of Medicine" reported that women with pre-eclampsia were more likely to develop kidney failure later in life. The risk was 0.7 times higher if a woman had pre-eclampsia in her first pregnancy, 6.4 times higher if she were pregnant twice and had pre-eclampsia in both pregnancies and 15.5 greater in women with more than three pregnancies who had pre-eclampsia in at least two.
References
- PubMed Health; Pre-Eclampsia; September 2009
- Drugs.com: Magnesium Sulfate
- Uninet; Focus on Preeclampsia: A Nephrologist's Point of View; Amelia R. Bernasconi; 2007
- "New England Journal of Medicine"; Preeclampsia and the Risk of End-Stage Renal Disease; B. Vikse, M.D., et al.; August 2008
- University of North Carolina Chapel Hill; Preeclampsia; Jeff Hollingsworth, M.D.; January 2003
