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PubMed This is a summary of 22 peer-reviewed journal articles Updated

Identifying ITP and Its Look-Alikes

At a Glance

Immune thrombocytopenia (ITP) is a diagnosis of exclusion, meaning doctors must rule out other causes of low platelets before confirming it. Secondary triggers like infections, lupus, or medications must be evaluated. Inherited genetic conditions can mimic ITP but require different care.

Diagnosing ITP is a process of elimination. Because there is no single “ITP test” that can provide a definitive “yes” or “no,” doctors must act like detectives to rule out other possible causes for low platelets [1]. This is why ITP is technically known as a diagnosis of exclusion [2].

Primary vs. Secondary ITP

When a cause for the low platelets cannot be found, it is called Primary ITP [1]. However, in many cases, the low platelet count is actually a side effect of another underlying issue. This is called Secondary ITP [3]. Common triggers include:

  • Infections: Viruses like HIV, Hepatitis C (HCV), and COVID-19 can trigger the immune system to attack platelets [4][5]. A common stomach bacteria called H. pylori is also a frequent culprit; in some patients, treating the bacteria actually cures the low platelet problem [6][7].
  • Autoimmune Diseases: Conditions like Systemic Lupus Erythematosus (SLE) or Lupus can cause the body to attack multiple parts of the blood, including platelets [8].
  • Medications: Certain drugs (like specific antibiotics or anticoagulants) can cause Drug-Induced Thrombocytopenia (DITP), where the medicine itself triggers the immune system to destroy platelets [9][10].

The “Look-Alikes”: Inherited Conditions

Some people are born with a low platelet count due to genetic variants. These are called inherited thrombocytopenias, and they are the most common “mimics” of ITP [11].

  • MYH9-Related Disease: This is a common genetic condition often misdiagnosed as ITP [12].
  • The Danger of Misdiagnosis: This is critical because inherited conditions do not respond to standard ITP treatments like steroids or surgery to remove the spleen [13][14]. Treating a genetic condition with ITP drugs can lead to unnecessary side effects without raising the platelet count.
  • Family History: If multiple family members have low platelets, or if your ITP doesn’t respond to typical treatments, your doctor may suggest genetic testing [13][15].

Is a Bone Marrow Biopsy Necessary?

A bone marrow biopsy involves taking a small sample of the spongy tissue inside your bones to see how platelets are being made. For most people—especially children—this is not a standard part of the diagnosis [16][17].
Doctors usually only suggest a biopsy if:

  1. The patient is older (typically over 60) to rule out other age-related bone marrow issues [18][19].
  2. The blood work shows other abnormalities (like low red or white blood cells) [20][21].
  3. The condition does not respond to standard treatments as expected [22].

By systematically ruling out these “look-alikes,” your care team ensures that your diagnosis is accurate and your treatment plan is safe [1].

For information on how the diagnosis is supported by lab work, see Understanding Your Labs and Blood Counts.

Return to the Home Page.

Common questions in this guide

Is there a specific test to diagnose ITP?
No, there is no single test for ITP. It is considered a diagnosis of exclusion. This means your doctor will run tests to rule out other possible causes for your low platelet count, such as infections or other diseases, before confirming an ITP diagnosis.
What is the difference between primary and secondary ITP?
Primary ITP occurs when no underlying cause for low platelets can be found. Secondary ITP happens when the low platelet count is triggered by another issue, such as a viral infection, a bacterial infection like H. pylori, an autoimmune disease like lupus, or certain medications.
Will I need a bone marrow biopsy to be diagnosed with ITP?
A bone marrow biopsy is not a standard requirement for diagnosing ITP, especially in children. Doctors typically only recommend it if you are older than 60, have other abnormalities in your blood work, or if your condition does not respond to standard treatments.
Could my low platelets be caused by a genetic condition instead of ITP?
Yes, inherited thrombocytopenias, such as MYH9-related disease, are genetic conditions that cause low platelets and are often misdiagnosed as ITP. If you have a family history of low platelets or do not respond to standard ITP treatments, your doctor may suggest genetic testing to check for these variants.
Can infections cause my platelets to drop?
Yes, certain infections can trigger the immune system to attack platelets. Common viral triggers include HIV, Hepatitis C, and COVID-19. A stomach bacteria called H. pylori can also cause low platelets, and in some cases, treating the bacteria may resolve the platelet issue.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Why do you believe my (or my child's) case is primary ITP rather than secondary to an infection or another condition?
  2. 2.Have you reviewed my full medication and supplement list for potential drug-induced thrombocytopenia?
  3. 3.Given my family history, should we consider genetic testing for inherited thrombocytopenias like MYH9-related disease?
  4. 4.Are there any 'atypical' features in my blood work that would make a bone marrow biopsy necessary?
  5. 5.Have I been screened for H. pylori, HIV, and Hepatitis C as part of this diagnostic process?

Questions For You

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References

References (22)
  1. 1

    Immune thrombocytopenia associated with Helicobacter pylori - unclear associative mechanisms.

    Marques AR, Sousa L, Mendes M, Apolinário I

    Hematology, transfusion and cell therapy 2019; (41(3)):272-274 doi:10.1016/j.htct.2018.12.002.

    PMID: 31101516
  2. 2

    State of the art - how I manage immune thrombocytopenia.

    Cooper N

    British journal of haematology 2017; (177(1)):39-54 doi:10.1111/bjh.14515.

    PMID: 28295192
  3. 3

    Misdiagnosed thrombocytopenia in children and adolescents: analysis of the Pediatric and Adult Registry on Chronic ITP.

    Schifferli A, Heiri A, Imbach P, et al.

    Blood advances 2021; (5(6)):1617-1626 doi:10.1182/bloodadvances.2020003004.

    PMID: 33710335
  4. 4

    Clinical characteristics, management and outcome of COVID-19-associated immune thrombocytopenia: a French multicentre series.

    Mahévas M, Moulis G, Andres E, et al.

    British journal of haematology 2020; (190(4)):e224-e229 doi:10.1111/bjh.17024.

    PMID: 32678953
  5. 5

    Recurrence of immune thrombocytopenia at the time of SARS-CoV-2 infection.

    Merli M, Ageno W, Sessa F, et al.

    Annals of hematology 2020; (99(8)):1951-1952 doi:10.1007/s00277-020-04130-2.

    PMID: 32529284
  6. 6

    Thrombocytopenia and infections.

    Franchini M, Veneri D, Lippi G

    Expert review of hematology 2017; (10(1)):99-106 doi:10.1080/17474086.2017.1271319.

    PMID: 27936979
  7. 7

    An Unusual Cause of Secondary ITP in a 34-Year-Old Hispanic Male.

    Bangolo A, Ahmed M, Atoot A, et al.

    Case reports in hematology 2021; (2021()):7965930 doi:10.1155/2021/7965930.

    PMID: 34976420
  8. 8

    Primary Immune Thrombocytopenic Purpura (ITP) and ITP Associated with Systemic Lupus Erythematosus: A Review of Clinical Characteristics and Treatment Modalities.

    Bashyal KP, Shah S, Ghimire C, et al.

    International journal of rheumatology 2024; (2024()):6650921 doi:10.1155/2024/6650921.

    PMID: 38464849
  9. 9

    Bevacizumab-induced immune thrombocytopenia in an ovarian cancer patient with mixed connective tissue disease: case report and literature review.

    Zhang Y, Yang F, Wang J, et al.

    Frontiers in immunology 2024; (15()):1382964 doi:10.3389/fimmu.2024.1382964.

    PMID: 38903494
  10. 10

    Piperacillin-Tazobactam-Induced Immune Thrombocytopenia: A Case Report.

    Kiliaki S

    Journal of pharmacy practice 2023; (36(2)):451-452 doi:10.1177/08971900211048140.

    PMID: 34558345
  11. 11

    [Refractory immune thrombocytopenia revealing MYH9 related disease in a 64-year-old man].

    Bodard Q, Fredon G, Riche A, et al.

    La Revue de medecine interne 2025; (46(4)):236-239 doi:10.1016/j.revmed.2024.12.005.

    PMID: 39939231
  12. 12

    A novel variant of MYH9 mutation associated macro-thrombocytopenia: A case series.

    Wadhera S, Sharma R, Sahni A, et al.

    Transfusion and apheresis science : official journal of the World Apheresis Association : official journal of the European Society for Haemapheresis 2025; (64(6)):104254 doi:10.1016/j.transci.2025.104254.

    PMID: 40934793
  13. 13

    Comprehensive genetic analysis for identification of monogenic disorders and selection of appropriate treatments in pediatric patients with persistent thrombocytopenia.

    Sato D, Kirikae H, Nakano T, et al.

    Pediatric hematology and oncology 2024; (41(8)):541-556 doi:10.1080/08880018.2024.2395358.

    PMID: 39318204
  14. 14

    The role of genetic sequencing in the diagnostic workup for chronic immune thrombocytopenia.

    Joshi N, Lango-Allen H, Downes K, et al.

    Blood advances 2025; (9(7)):1497-1507 doi:10.1182/bloodadvances.2024014639.

    PMID: 39808791
  15. 15

    Validation of immunofluorescence analysis of blood smears in patients with inherited platelet disorders.

    Zaninetti C, Leinøe E, Lozano ML, et al.

    Journal of thrombosis and haemostasis : JTH 2023; (21(4)):1010-1019 doi:10.1016/j.jtha.2022.12.031.

    PMID: 36732160
  16. 16

    [Protocol for the study and treatment of primary immune thrombocytopenia: PTI-2018].

    Monteagudo E, Astigarraga I, Cervera Á, et al.

    Anales de pediatria 2019; (91(2)):127.e1-127.e10 doi:10.1016/j.anpedi.2019.04.014.

    PMID: 31178291
  17. 17

    A four-point clinical criteria distinguishes immune thrombocytopenia from acute lymphoblastic leukaemia.

    Lum SH, How SJ, Ariffin H, Krishnan S

    The Medical journal of Malaysia 2016; (71(1)):28-9.

    PMID: 27130741
  18. 18

    Bone Marrow Disease Profile in Geriatric Patients: An Institutional Experience.

    Gulati A, Mandal T, Kaushal V, et al.

    Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion 2018; (34(3)):540-543 doi:10.1007/s12288-017-0871-3.

    PMID: 30127568
  19. 19

    Bone marrow examination in geriatric patients-An institutional experience from the north Himalayan region of India.

    Chandra H, Gupta AK, Arathi K, et al.

    Journal of family medicine and primary care 2019; (8(12)):3931-3934 doi:10.4103/jfmpc.jfmpc_792_19.

    PMID: 31879638
  20. 20

    Re-evaluation of Need for Bone Marrow Examination in Patients with Isolated Thrombocytopenia Contributors.

    Purohit A, Aggarwal M, Singh PK, et al.

    Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion 2016; (32(2)):193-6 doi:10.1007/s12288-015-0533-2.

    PMID: 27065582
  21. 21

    Patterns of Bone Marrow Confirmed Malignant and Non-Malignant Hematological Disorders in Patients with Abnormal Hematological Parameters in Northeast Ethiopia.

    Ebrahim H, Fisha T, Debash H, Bisetegn H

    Journal of blood medicine 2022; (13()):51-60 doi:10.2147/JBM.S346091.

    PMID: 35210892
  22. 22

    Acalabrutinib and steroid for autoimmune thrombocytopenia due to relapsed chronic lymphocytic leukemia with severe bone marrow infiltration.

    Oyama T, Yasunaga M, Jona M, et al.

    Journal of clinical and experimental hematopathology : JCEH 2023; (63(3)):187-192 doi:10.3960/jslrt.23023.

    PMID: 37635085

This page provides educational information about diagnosing ITP and ruling out similar conditions. It is not a substitute for professional medical advice, diagnosis, or testing from your hematologist or care team.

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