Thrombotic thrombocytopenic purpura laboratory findings

An elevated concentration of creatinin, indirect bilirubin, retic count, dark urinary, schistocytes in peripheral blood smear is diagnostic of TTP.

• CBC shows:
  • Thrombocytopenia (median platelet count 10,000/microL)
  • Microangiopathic hemolytic anemia ^[1]:

• Peripheral blood smear: Schistocytes, including helmet cells and triangular cells, polychromasia, micro spherocytes and nucleated RBCs
• Urinalysis: Hematuria, proteinuria
• Serum creatinine: Increased
• Urine output: Decreased
• ADAMTS13 test: ADAMTS13 activity or inhibitor provides information for the diagnosis of the types and causes of TTP;
  • ADAMTS13 activity: Decreased to < 10% during acute episodes of TTP.
  • ADAMTS13 inhibitors test: This test is performed for patients with severe deficiency of ADAMTS13.
• Genetic testing: Should be done in suspected cases of,
  • Positive family history
  • Recurrent episodes
  • Onset during childhood or pregnancy
  • Absence of inhibitors
  • Persistent ADAMTS13 deficiency
• Imaging: In cases with higher suspicion of TTP, imaging is not necessary but with focal neurological signs MRI or CT may be considered
• Blood culture: Patients with fever or signs and symptoms of infections
• Stool exam: Stool culture and toxin evaluation should be considered in patients with diarrhea as one of the main presentation especially bloody diarrhea
• Pathology: Tissue biopsy is not necessary for diagnosis, but it may show classic changes of a thrombotic microangiopathy including platelet microthrombi in small arterioles or capillaries, or hyaline changes in and around vessel walls.

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