A Review of AFPs "Hemolytic Uremic Syndrome: An Emerging Health Risk"

Hemolytic Uremic Syndrome: An Emerging Health Risk
SAMIYA RAZZAQ, M.D., University of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas
Am Fam Physician. 2006 Sep 15;74(6):991-996.
http://www.aafp.org/afp/2006/0915/p991.pdf

    I choose to write about HUS (hemolytic uremic syndrome) because I am attending a dinner lecture on it and I thought it would be a good excuse to brush up on the topic (there is no reason to look like a fool if it can be avoided).  There are two types of HUS. There is the diarrhea-positive HUS, which occurs more commonly in children and is due to an E.coli born shiga toxin. The other type is due to genetics, drugs (cyclosporine, tacrolimus, radiation), cancer, or it may be idiopathic.
    The pathophysiology is not well understood. Damage to the endothelial cells are due to prothrombotic and proinflammatory states. This leads to MAHA (microangiopathic hemolytic anemia), thrombocytopenia, and renal injury (this is a triad). The E.coli O157:H7 can come from undercooked beef, unpasteurized goat's milk and apple juice, sprouts, petting zoos, contaminated lakes, or person to person contact (its a reportable disease).  In the infectious type, antibiotics and antidiarrheal medications will only make it worse.
     Hemolytic anemia is needed for the diagnosis. A hemoglobin at or below 6 will need a blood transfusion. Platelet transfusion will exacerbate the thrombosis and is not recommended. The microthrombi from the hemolysis will deposit in the kidneys and cause acute renal failure (or maybe you would rather me use the term acute kidney injury, but this article is from 2006, so there goes being politically correct). The CNS can can be affected and cause irritability, seizures and altered mental status. Other lab abnormalities include azotemia, decreased haptoglobin, elevated CRP, burr cells, helmet cells, leukocytosis, elevated reticulocyte count, platelet count less than 50,000, hematuria, and proteinuria.
     HUS is self limiting and treatment consists of proper nutrition and close monitoring of electrolyte and volume status. Dialysis is an option for some patients. Hemoglobin and the platelet count need to be monitored regularly as well. Diarrhea associated HUS has a very good prognosis. The other type has a poor prognosis , with incomplete recovery and a 10% mortality rate.