Diagnosis of thrombotic thrombocytopenic purpura

Laboratory diagnostics of thrombocytopenic purpura

Laboratory examination reveals thrombocytopenia less than 100,000/mm3 ^, an increase in the mean platelet volume (MPV) according to an automatic blood analyzer to 8.9±1.5 ^μm3.

Classification of platelet diseases based on their size

MPV increased	MPV norm (7.1 microns)	MPV reduced
ITP and other conditions with increased platelet production and consumption, including DIC	Conditions in which the bone marrow is low in cells or affected by malignant diseases	Wiskott-Aldrich syndrome
May-Hegglin anomaly	-	Storage diseases
Alport syndrome	-	Iron deficiency anemia
Mucopolysaccharidosis, gray platelet syndrome
Leaky Platelet Syndrome (Swiss Cheese)	-	-
Montreal Platelet Syndrome	-	-
Bernard-Soulier syndrome	-	TAR syndrome

In addition to thrombocytopenia, patients with idiopathic thrombocytopenic purpura may have moderate eosinophilia in their peripheral blood. With severe blood loss, anemia develops.

In a bone marrow puncture, which is carried out to exclude other oncohematological diseases, irritation of the megakaryocytic lineage, weak "pinching" of thrombocytes with normal erythroid and myeloid lineages are found. In some patients, moderate eosinophilia is detected.

When studying the coagulation profile, which is not mandatory in standard idiopathic thrombocytopenic purpura, they reveal an increase in bleeding time, a decrease or absence of clot retraction, impaired prothrombin utilization with normal levels of fibrinogen, prothrombin time, and activated partial thromboplastin time.

Laboratory tests in patients with thrombocytopenia include:

• general blood test with smear and determination of platelet count;
• bone marrow puncture examination;
• blood test for ANF, anti-DNA, complement fractions C3, C4, antiplatelet antibodies, plasma glycocalcin level, Coombs test;
• determination of prothrombin time, activated partial thromboplastin time, fibrinogen level, fibrinogen breakdown products;
• determination of urea, blood creatinine, liver function tests;
• blood test for opportunistic infections (HIV, Epstein-Barr virus, parvovirus);
• exclusion of secondary forms of thrombocytopenia.

The main criteria for diagnosing idiopathic thrombocytopenic purpura are:

• absence of clinical signs of systemic and oncohematological diseases;
• isolated thrombocytopenia with normal numbers of red blood cells and white blood cells;
• normal or increased number of megakaryocytes in the bone marrow with normal erythroid and myeloid elements;
• exclusion of secondary forms of thrombocytopenia in hypersplenism, microangiopathic hemolytic anemia, DIC syndrome, drug-induced thrombocytopenia, systemic lupus erythematosus, viral infections (Epstein-Barr virus, HIV, parvovirus).

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