Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a rare condition affecting mostly children under the age of 10. HUS is characterized by destruction of red blood cells, damage to the lining of blood vessel walls, and, in severe cases, kidney failure.

Most cases of HUS occur after an infection in the digestive system caused by the Escherichia colibacterium found on contaminated food like meat, dairy products, and juice. The first stages of HUS frequently present with gastrointestinal symptoms such as abdominal pain, vomiting, and bloody diarrhea. This stage lasts from 1 to 15 days. Recovery from this acute colitic phase is the rule. However, more severe problems in the bowel and colon may develop in some cases. (The most vulnerable and severely stricken of children with HUS can die during the first acute stage of the disease--between 5 percent and 10 percent.)

For most children with HUS, the vomiting and diarrhea stop after 2 or 3 days. Even when the gastroenteritis has stopped, the child does not recover full health, remaining pale, tired, and irritable. The bacteria originally lodged in the digestive system make toxins that enter the bloodstream, and these toxins destroy red blood cells. Small, unexplained bruises or small clot-sized hemorrhages visible in the mucosal lining of the mouth may occur because the toxins also destroy the platelets, cells that normally contribute to the clotting system.

The damaged red blood cells and other factors may clog the tiny blood vessels in the kidneys or cause lesions in the kidneys, making the kidneys work harder to remove wastes and extra fluid from the blood. The child may produce little urine as a result. The body's inability to rid itself of excess fluid and waste may in turn cause hypertension or swelling of the hands and feet or may cause generalized fluid accumulation ( edema ).

Once HUS develops, there is no known treatment that can stop the progress of the syndrome. Unfortunately, it must run its course. Most treatments are supportive in nature and aimed at easing the immediate symptoms and signs of this disease and at preventing further complications. Supportive therapy consists of maintaining specific levels of fluids and salts, which are replaced only as needed. Blood transfusions (packed red blood cells) are sometimes needed. Treatment of high blood pressure is often necessary. Dialysis is also needed at times to help the kidneys perform their function. Other complications, such as neurologic complications, necessitate additional medications.

Ninety percent of children with HUS who receive careful supportive care survive past the initial harrowing stages of the condition, and most of those will have no long-term effects. But between 10 percent and 30 percent of the survivors will have kidney damage that leads to permanent kidney failure either immediately or over the course of several years. Most children with kidney failure will require peritoneal dialysis or hemodialysis to wash the wastes and extra fluid from their blood or may require a kidney transplant.