Recognize Thrombotic Microangiopathy

Recognize Thrombotic Microangiopathy

Recognize Thrombotic Microangiopathy

Recognize Thrombotic Microangiopathy

1.Thrombocytopenia?
2.Microangiopathic Hemolysis?
3.Neurologic Symptoms?
4.Renal Impairment?
5.Gastrointestinal Symptoms?
6.Cardiac/Circulatory Symptoms?
Created by on 29/11/2015

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About this Calculator

Clarifying the specific diagnosis of a thrombotic microangiopathy requires 4 steps:

  1. The thrombotic microangiopathy must first be recognized, as indicated by schistocytes on blood smear, low haptoglobin levels and reduced hemoglobin levels. It should be noted that schistocytes may be infrequent on initial presenation. While thrombocytopenia generally accompanies these findings, the degree of thrombocytopenia tends to varies by specific diagnosis. In TTP, severe decline in platelets are typical, while in aHUS, thrombocytopenia may be less pronounced.
  2. Detect involvement of at least one organ system, the 3 most common being neurologic, renal and gastrointestinal. It should be noted that TTP and aHUS can result in microvessel thrombosis with ischemia and infarction in almost any tissue. The only possible exception would be that lung involvement is almost never present in TTP but can be seen in aHUS.
  3. Distinguish STEC-HUS from aHUS or TTP by assessing for Shiga-toxin producing E. coli via culture-based assays or PCR. Since aHUS can frequently be complicated by diarrhea, as can TTP occasionally, gastrointestinal symptoms cannot be used to distinguish the specific type of TMA.
  4. Utilize ADAMTS13 activity levels to distinguish TTP from aHUS.

    To obtain information about ADAMTS13 activity testing in Canada, visit qxmd.com/ADAMTS13

    ADAMTS13 levels of ≤ 5% are compatible with TTP. When ADAMTS13 levels are not drawn prior to starting plasma exchange, monitoring of clinical response is required. In a patient diagnosed with TTP who experiences only a limited response to plasma exchange or requires plasma volume that exceed typical values, the etiology of TMA may need to be re-evaluated.

    When ADAMTS13 levels are >5%, consideration should also be made to the possibility of secondary causes of thrombotic microangiopathy.

    Secondary causes include:

    • Pregnancy
    • HELLP syndrome
    • Lupus
    • Anti-phospholipid syndrome
    • Scleroderma
    • HIV infection
    • Malignant hypertension
    • H1N1 infection (influenza A)
    • Pneumococcal pneumonia
    • Disseminate Cancer
    • Bone marrow transplant
    • Methylmalonic aciduria with homocysteinuria
    • Drugs/Treatments eg quinine, ticlopidine and clopidogrel, mitomycin, gemcitabine, cisplatin, ionizing radiation, interferon, VEGF and tyrosine kinase (sunitinib, imtinib, and dasatinib), calcineurin inhibitors (cyclosporine, tacrolimus), sirolimus

Acronyms:

  • TMA: Thrombotic microangiopathy
  • TTP: Thrombotic thrombocytopenic purpura
  • aHUS: Atypical hemolytic uremic syndrome
  • STEC-HUS: Shiga toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome
  • ADAMTS13: a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13

References

Laurence J.

Atypical hemolytic uremic syndrome (aHUS): making the diagnosis.

Clinical Advances in Hematology & Oncology: H&O 2012, 10 (10 Suppl 17): 1-12

Zuber J, Fakhouri F, Roumenina LT, Loirat C, Fremeaux-Bacchi V.

Use of eculizumab for atypical haemolytic uraemic syndrome and C3 glomerulopathies.

Nature Reviews. Nephrology 2012, 8 (11): 643-57

Kremer Hovinga JA, Lämmle B.

Role of ADAMTS13 in the pathogenesis, diagnosis, and treatment of thrombotic thrombocytopenic purpura.

Hematology—the Education Program of the American Society of Hematology 2012, 2012: 610-6

George JN, Al-Nouri ZL.

Diagnostic and therapeutic challenges in the thrombotic thrombocytopenic purpura and hemolytic uremic syndromes.

Hematology—the Education Program of the American Society of Hematology 2012, 2012: 604-9

The Recognize Thrombotic Microangiopathy calculator is created by QxMD.

1. Thrombocytopenia?

More Information

Thrombocytopenia defined as Platelet <150x10⁹/L or >25% Decrease from Baseline

Created by on 29/11/2015

By using this site you acknowledge that you have read, understand, and agree to be bound by our terms of use and privacy policy. All content and tools are for educational use only, are not meant to be a substitute for professional advice and should not be used for medical diagnosis and/or medical treatment.

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