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Hemolytic uremic syndrome (HUS) is a rare condition characterized by destruction of red blood cells, damage to the lining of blood vessel walls, and, in severe cases, kidney failure.
Incidence; Causes & Development
HUS affects mostly children under the age of 10.
Most cases of HUS occur after an infection in the digestive system caused by the Escherichia colibacterium found on contaminated food such as meat, dairy products and juice.
Signs & Symptoms
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 5-10% most vulnerable and severely stricken of children with HUS can die during the first acute stage of the disease.)
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).
Treatment & Prevention
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.
Prognosis; Complications
Some 90% 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.
Unfortunately, between 10 and 30% 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.
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GLOSSARY
Abdomen (Abdominal)
That part of the body between the chest and the hips that contains the stomach, intestines, liver, bladder, pancreas and other organs.
Acute
An illness or symptom of sudden onset, which generally has a short duration.
Bacteria (Bacterial, Bacterium)
Microscopic germs. Some bacteria are "harmful" and can cause disease, while other "friendly" bacteria protect the body from harmful invading organisms.
Chronic Renal Failure (Chronic Renal Insufficiency, Kidney Failure, Renal Insufficiency)
(CRF) Irreversible, progressive impaired kidney function. The early stage, when the kidneys no longer function properly but do not yet require dialysis, is known as Chronic Renal Insufficiency (CRI). CRI can be difficult to diagnose, as symptoms are not usually apparent until kidney disease has progressed significantly. Common symptoms include a frequent need to urinate and swelling, as well as possible anemia, fatigue, weakness, headaches and loss of appetite. As the disease progresses, other symptoms such as nausea, vomiting, bad breath and itchy skin may develop as toxic metabolites, normally filtered out of the blood by the kidneys, build up to harmful levels. Over time (up to 10 or 20 years), CRF generally progresses from CRI to End-Stage Renal Disease (ESRD, also known as Kidney Failure). Patients with ESRD no longer have kidney function adequate to sustain life and require dialysis or kidney transplantation. Without proper treatment, ESRD is fatal.
Colon (Colonic)
The part of the large intestine that extends to the rectum. The colon takes the contents of the small intestine, moving them to the rectum by contracting.
Dialysis
The artificial process of cleaning wastes from the blood when kidneys fail.
Diarrhea
Excessive discharge of contents of bowel.
Edema
Abnormal accumulation of fluids within tissues resulting in swelling.
Gastroenteritis
Gastrointestinal tract inflammation; characterized by abdominal pain, nausea, diarrhea, vomiting; which may be caused by bacteria, parasites or a virus.
Gastrointestinal (GI, GI Tract)
Pertaining to the stomach, small and large intestines, colon, rectum, liver, pancreas, and gallbladder.
Hemodialysis
Process of separating water and small soluble substances from the blood.
Hemolytic
Promoting the breakdown of red blood cells; a normal process, hectic and skillfully balanced, the term is usually applied to excess conditions or toxic substances that degrade the bonds between healthy red blood cells and their hemoglobin coat or cause the liver and spleen to hypercatabolize otherwise healthy erythrocytes.
Hypertension
High blood pressure. Hypertension increases the risk of heart attack, stroke, and kidney failure because it adds to the workload of the heart, causing it to enlarge and, over time, to weaken; in addition, it may damage the walls of the arteries.
Kidneys (Kidney, Renal)
Bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage. The kidneys are sophisticated reprocessing machines, each day handling about 50 gallons of blood to sift out about half a gallon of waste products and extra water. The waste and extra water become urine, which flows to the bladder through tubes called ureters. The actual filtering occurs in tiny units inside the kidneys called nephrons. Every kidney has about a million nephrons. In a nephron, a glomerulus -- which is a tiny blood vessel, or capillary -- intertwines with a tiny urine-collecting tube called a tubule. A complicated chemical exchange takes place, as waste materials and water leave your blood and enter your urinary system. The kidneys recycle chemicals such as sodium, phosphorus, and potassium and thus regulate their levels. Renal: Pertaining to the kidneys.
Lesion (Lesions)
Any damage to tissue structure or function; an abnormal change in body tissue caused by disease or injury. A scar is a lesion, as is cancer, a stomach ulcer or a pimple.
Platelets (Platelet)
Cells that help the blood to clot.
Red Blood Cell (Erythrocyte, Erythrocytes, RBC, Red Blood Cells)
Any of the hemoglobin-containing cells that carry oxygen to the tissues and are responsible for the red color of blood.
Syndrome
A medical condition characterized by a collection of related symptoms (what the patient feels) and signs (what a doctor can observe or measure).
Last updated: Apr 13, 2008
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