Pathophysiology
Hemolytic uremic syndrome (HUS) is a serious and potentially life-threatening medical condition resulting from the destruction of red blood cells and kidney failure. HUS affects children more than adults, with a peak incidence between 4 and 10 years of age. It is the result of a bacterial blood infection, caused by certain types of E. coli bacteria. This bacteria then attacks the lining of the child’s small intestine and causes a “leakage” of various cells into the body’s circulation. If the infection to the bowel becomes severe, it can lead to the formation of red blood cells through abnormalities in the production of their membrane proteins. The composition of urine will then start to fade until it becomes very dark red or even maroon coloration.(3)
It results from immune-mediated destruction of red blood cells and platelets, as well as thrombocytopenia. The patient suffers from internal bleeding, renal failure, and neurological impairment. Eventually, the patient may develop acute renal failure leading to death.
HUS may also be precipitated by other causes such as: contaminants in food or water, the use of certain drugs such as steroids and cancer chemotherapy, exposure to monoclonal antibodies and molecularly cloned human proteins, and autoimmune disorders. HUS occurs ten to twenty times more frequently in persons under the age of five than in older children and adults. In most instances, it is self-limiting, and complete recovery takes place in two weeks to six months. The most at-risk population for developing HUS is toddlers 5 years or younger and of western European descent. If developed, there are two main complications that can lead to death: circulatory collapse and acute kidney failure. The overall mortality rate is approximately 10%.