Hemolytic uremic syndrome (HUS) is defined as a triad of microangiopathic hemolytic anemia, thrombocytopenia and renal dysfunction. It is one of the main causes of acute kidney injury in children.  In the past.

Diarrhea (+) HUS primarily results form a Shiga toxin-producing Escherichia coli (STEC) infections (90%), and less frequently from Shigella dysenteriae type 1 infection

Clinical Manifestation: prodromal diarrhea 5-10 days prior (abdominal pain, bloody diarrhea, nausea, vomiting). Renal involvement (eg: oliguria & hematuria).

Pathophysiology: The toxins enter the blood where it damages endothelium, activating platelets and causing microthrombi formation/blood clots. Eventually the platelets deplete. The toxins damage the kidney and lead to uremia.

History of possible exposure to Shiga toxin-producing Escherichia coli (STEC) should include questions about ingestion of undercooked ground beef or other foods that may be fecally contaminated by cattle, swimming in a potentially contaminated lake or pool, or contact with farm animals.

 

Workup, treatment, differential

Diagnosis and workup:

The diagnosis of hemolytic uremic syndrome (HUS) is clinically based on the presence of the classical triad

1. Microangiopathic hemolytic anemia: weakness, fatigue, lethargy, jaundice due to RBC destruction)
2. Thrombocytopenia: low platelets, clots can’t form, easy bruising and purpura, also can get blood clots in the brain leading to visual problems, seizure and stroke, fever)
3. Renal dysfunction: uremia or excess urea in blood.

Laboratory test:

complete blood count (CBC):

• Microangiopathic hemolytic anemia: hemoglobin level less than 8 g/dL with a negative Coomb’s test and a peripheral blood smear demonstrating a large number of schistocytes (up to 10 percent of red cells) and helmet cells.
• renal functions studies and urinalysis: for signs of acute kidney injury- proteinuria, hematuria, waste products, elevated serum creatinine and blood urea nitrogen [BUN] levels and oligoanuria.

Coagulation studies:

• Thrombocytopenia: platelet count below 140,000/mm³ and is usually approximately 40,000/mm But will have normal coagulation studies(pt/ptt)- helps to distinguish from disseminated intravascular coagulation (DIC).

Screening for Shiga toxin-producing bacterial strains: Shiga toxins (eg, ELISA) in the stool, stool cultures, and serologic testing for IgM and anti-lipopolysaccharide antibodies against the most frequent STEC serotypes.

Peripheral Blood smear– schistocytes (up to 10%) and helmet cells which are signs of hemolysis

Differential :

• Disseminated intravascular coagulation (DIC) is distinguished from HUS by the presence of abnormal coagulation studies, including prolonged prothrombin time and activated partial thromboplastin time, and elevated levels of fibrin degradation products and D-dimer.
• Thrombotic thrombocytopenic purpura (TTP) is due to deficient activity of the Von Willebrand factor cleaving protease
• Systemic vasculitis – Patients with vasculitis typically have other systemic symptoms (such as arthralgias and rash) and do not have a prodromal diarrheal illness.

Treatment:

The initial management of hemolytic uremic syndrome (HUS) is supportive

– Red blood cell transfusions for anemia (eg, hemoglobin level reaches 6 to 7 g/dL or hematocrit <18 percent).

– Platelet transfusion for patients who have significant clinical bleeding.

– fluid and electrolyte management

– Stopping nephrotoxic drugs or those that are implicated in the etiology of HUS.

– Dialysis therapy in patients with symptomatic uremia, azotemia (

 

Source:

https://www-uptodate-com.york.ezproxy.cuny.edu/contents/overview-of-hemolytic-uremic-syndrome-in-children?search=hemolytic%20uremic%20syndrome%20children&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1