The hemolytic uremic syndrome (HUS) is defined by the simultaneous occurrence of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury . It is one of the main causes of acute renal injury in children under the age of three years.
This disorder is divided by whether or not there is an association with bacteria that produce a Shiga toxin .
- Shiga toxin associated HUS – Shiga toxin (Stx) associated HUS is the most common form of HUS in children accounting for 90 percent of all cases. It usually occurs after a prodromal episode of diarrhea that is frequently bloody. In the majority of cases, typical HUS is associated with strains of Escherichia coli that produce a Shiga toxin [3-6]. This form is also referred to as typical, classical, or diarrhea-associated HUS, D+ HUS, or Shiga toxin-associated HUS.
Cases of HUS in children due to Shiga toxin-producing Escherichia coli (E. coli) infections other than colitis (eg, urinary tract infections) can occur [7,8]. Although these cases are not associated with diarrhea, the clinical course and pathophysiology are the same as the D+ HUS and will be included in the discussion on Stx HUS. In addition, D+ HUS associated with Shigella dysenteriae serotype 1 will be included in the discussion of Stx HUS [9,10].
- Non-Shiga toxin associated HUS – Non-Shiga toxin (NStx) associated HUS is a heterogeneous group of disorders distinguished clinically by the absence of diarrhea or Shiga toxin-producing E. coli infection [11,12]. This disorder is also referred to as atypical, nondiarrhea-associated HUS, D- HUS, or sporadic HUS. Complement disorders involving factors H, I, and membrane cofactor protein and Streptococcus pneumoniae infection have been associated with cases of NStx HUS. The clinical manifestations, diagnosis, treatment, and prognosis of NStx HUS are presented separately. (See "Atypical hemolytic uremic syndrome in children".)
The clinical manifestations and diagnosis of Stx HUS in children are presented in this topic review. The treatment and prognosis of this disorder are presented separately. (See "Treatment and prognosis of Shiga toxin associated (typical) hemolytic uremic syndrome in children".)
Stx HUS is also a different disorder from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) in adults. This is discussed in detail separately. (See "Causes of thrombotic thrombocytopenic purpura-hemolytic uremic syndrome in adults".)