ITP – Lab Tests

Below are recommended tests in patients who present with presumed immune thrombocytopenia (ITP) (see Coach’s Corner section for additional information):

CBCIn all patientsIn all patientsIn all patients
Reticulocyte countNMIn all patientsNM
Peripheral smearIn all patientsIn all patientsIn all patients
HIV and HCV infection “The majority of authors routinely test for hepatitis B virus (HBV), HIV, and HCV in all adult patients.”In all patients.In all patients.
Prothrombin time, activated partial thromboplastin timeNMAdditional tests are requested in selected patients based on the findings of the basic evaluation.In individuals with moderate or severe thrombocytopenia, those with concerns about clinically important bleeding, and/or those who have planned invasive procedures. The purpose is to investigate and treat other potential causes of thrombocytopenia (eg, liver disease) and bleeding (eg, vitamin K deficiency).
H. pyloriThe detection of Helicobacter pylori infection, with the
urea breath test or the stool antigen test, should be
included in the initial work-up in appropriate geographical areas.
Additional tests are requested in selected patients based on the findings of the basic evaluation.Testing for H. pylori is appropriate in patients with gastrointestinal symptoms suggestive of infection because of a reported association between ITP and H. pylori infection. Routine screening for H. pylori may be reasonable in asymptomatic individuals as well, especially those from countries where H. pylori infection is endemic (e.g., Japan). H. pylori-induced ITP is expected to be rare in the United States and Canada.
Thyroid function testingTests of potential utility in the management of an ITP patient.Additional tests are requested in selected patients based on the findings of the basic evaluation.Thyroid function testing is appropriate in patients with symptoms of hypo- or hyperthyroidism because of rare reports of ITP associated with thyroid disorders.
Bone marrow examinationBased on the evidence currently available, when there is isolated thrombocytopenia and no abnormal features present on physical examination or examination of the blood smear, a bone marrow examination is not required in the initial diagnosis, whether or not treatment is recommended.

Bone marrow examination could be appropriate in those relapsing after remission, in patients not responding to initial treatment options, where splenectomy is considered, or if other abnormalities are detected in the blood count or morphology.
Bone marrow examination is not required routinely and is generally not useful for diagnosing ITP, but should be performed to exclude other causes of thrombocytopenia when atypical features such as unexplained anemia, lymphadenopathy, or splenomegaly are present. 

Failure to respond to first line agents should prompt consideration of bone marrow examination and other causes of thrombocytopenia.

Bone marrow examination may also be warranted in elderly patients in whom myelodysplasia is suspected. 
Bone marrow examination may be indicated for patients with other unexplained cytopenias (anemia, leukopenia), dysplasia on the peripheral blood smear, other unexpected hematologic findings, or other causes of thrombocytopenia, when suspected.

Patients whose platelet counts do not respond to ITP therapy may warrant a bone marrow examination to investigate for MDS or other platelet production abnormalities such as acquired amegakaryocytic thrombocytopenia.
Immunoglobulin levelsQuantitative immunoglobulin (Ig) level testing is indicated to exclude an immune deficiency syndrome
or before
treatment with IVIG.
Additional tests are requested in selected patients based on the findings of the basic evaluation.Quantitative immunoglobulin levels may identify underlying CVID or selective IgA deficiency, especially in younger patients.
*ICR, Updated international consensus report on the investigation and management of primary immune thrombocytopenia. ASH SAP; American Society of Hematology Self Assessment Program, 7th edition; UTD, Up-to-Date; CBC, complete blood count; NM, not mentioned; HCV, hepatitis C virus; CVID, common variable immune deficiency; IVIG, intravenous immune globulin.

See case study.

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