Differentials
Thrombotic thrombocytopenic purpura (TTP)
Malignant hypertension
Systemic lupus erythematosus (SLE)
SIGNS / SYMPTOMS
There are many overlapping features between SLE and TTP/HUS, and because the two can coexist, a distinction between them is generally not possible.[42]
INVESTIGATIONS
Serologic tests of underlying condition may be positive, but there are no tests to differentiate the cause of HUS.
Catastrophic antiphospholipid syndrome
INVESTIGATIONS
Antiphospholipid antibodies can be helpful in suggesting a diagnosis. However, even if these are positive, plasma exchange is often recommended in patients with manifestations of severe disease.[44]
Disseminated intravascular coagulation (DIC)
SIGNS / SYMPTOMS
Patients with DIC have a higher likelihood of bleeding manifestations and often have obvious predisposing causes, such as sepsis.
INVESTIGATIONS
The peripheral smear in a patient with DIC generally has fewer schistocytes. Coagulation parameters are typically abnormal in patients with DIC, whereas they are normal in patients with TTP/HUS.
Preeclampsia
SIGNS / SYMPTOMS
Distinguishing between the various causes of thrombocytopenia that present in the peri- and postpartum period can be difficult.[32][45] HUS tends to present postpartum, which distinguishes it from preeclampsia.
INVESTIGATIONS
The peripheral smear in patients with TTP/HUS generally has more schistocytes than are seen in preeclampsia.
HELLP syndrome
SIGNS / SYMPTOMS
HUS tends to present postpartum, which distinguishes it from HELLP (hemolysis, elevated liver enzyme levels, and a low platelet count) syndrome.
INVESTIGATIONS
The peripheral smear in patients with TTP/HUS generally has more schistocytes than are seen in HELLP syndrome.
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