Find information on thousands of medical conditions and prescription drugs.

Idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura is the condition of having a low platelet count (thrombocytopenia) of no known cause (idiopathic). As most causes appear to be related to antibodies against platelets, it is also known as immune thrombocytopenic purpura. Although most cases are asymptomatic, very low platelet counts can lead to a bleeding diathesis and purpura. more...

ICF syndrome
Ichthyosis vulgaris
Imperforate anus
Inborn error of metabolism
Incontinentia pigmenti
Infant respiratory...
Infantile spinal muscular...
Infective endocarditis
Inflammatory breast cancer
Inguinal hernia
Interstitial cystitis
Iodine deficiency
Irritable bowel syndrome

Signs and symptoms

ITP occurs most often in women over 40 years of age. It may be acute, lasting for 6 months or less, or chronic, lasting for over a year. The acute type is more often seen in children and will cure itself in more than 80% of cases. The chronic type is more commonly seen in adults and it tends to get worse as the disease progresses.

Occasionally, ITP patients suffer from bruising, nosebleeds, and bleeding gums; this is the characteristic pattern of bleeding in platelet disorders. Bleeding normally does not occur unless the platelet count is very low (below about 10,000 per mm3, compared to a normal range of 150,000–400,000 per mm3).

Subarachnoid and intracerebral hemorrhage are very serious possible complications of this disease. Fortunately, these are rare in patients who are being treated.


In many cases, the cause is not actually idiopathic but autoimmune, with antibodies against platelets being detected in approximately 80% of patients. Most often these antibodies are against platelet membrane glycoproteins IIb-IIIa or Ib-IX, and are of the IgG type. The coating of platelets with IgG renders them susceptible to opsonization and phagocytosis by splenic macrophages.

The IgG autoantibodies are also thought to damage megakaryocytes, the precursor cells to platelets, but this is thought to contribute only slightly to the decrease in platelet numbers.


When measuring the platelet count, one has to bear in mind that the "normal values" for laboratory measures are all statistical. They are defined by the upper and lower 2.5th percentile. It is therefore possible to be completely healthy but to have a decreased platelet count. There is, however, a higher chance of pathology.

The diagnosis of ITP is a clinical one and is a diagnosis of exclusion. Low platelet count can be a feature of a large number of diseases and, when serious, warrants investigation by a hematologist. Secondary causes include leukemia, medications (e.g. quinine), lupus erythematosus and some other autoimmune disorders, cirrhosis (leading to thrombocytopenia from hypersplenism), HIV, congenital causes, and antiphospholipid syndrome. A bone marrow examination may be performed on patients over the age of 60 and people who do not respond to treatment, or when the diagnosis is in doubt.

Despite the destruction of platelets by splenic macrophages, the spleen is normally not enlarged. In fact, an enlarged spleen should lead a clinician to investigate other possible causes for the thrombocytopenia.

Accelerated formation of platelets results in the presence of abnormally large platelets which are seen in a peripheral blood smear. Overall bleeding time is prolonged in these patients, but prothrombin time (PT) and partial thromboplastin time (PTT) are normal (because the problem is with the platelets, not with the coagulation cascade).


[List your site here Free!]

Idiopathic thrombocytopenic purpura diagnosis in children - Tips From Other Journals
From American Family Physician, 10/15/98 by Jeffrey T. Kirchner

Idiopathic thrombocytopenic purpura is a relatively common pediatric disorder. It tends to follow a self-limited course, but treatment with gamma globulin or corticosteroids is often instituted to prevent bleeding complications. It has been standard practice to perform a bone marrow aspiration to rule out leukemia as part of the initial work-up of a child with an abnormally low platelet count. Several older studies questioned the need for this procedure but did not provide convincing evidence because of small sample size or methodology. Calpin and associates performed a retrospective study to determine whether any diagnoses of leukemia were discovered in a large series of bone marrow aspiration samples that were collected from children diagnosed with acute idiopathic thrombocytopenic purpura who had typical hematologic features of this disease.

The reports of all bone marrow aspirations performed at the Hospital for Sick Children in Toronto from January 1, 1984, until May 31, 1996, were reviewed. This cohort included both inpatient and outpatient reports on bone marrow aspirations that were performed to confirm a provisional diagnosis of idiopathic thrombocytopenic purpura. The peripheral blood smear and complete blood count performed nearest to the time of the bone marrow aspiration were also reviewed to see if the patient had typical features of idiopathic thrombocytopenic purpura. "Typical features" included a normal hemoglobin, a normal total white blood cell and neutrophil count, and a platelet count of less than 50,000 x [10.sup.3] per [micro] L (50,000 x [10.sup.9] per L). The researchers then analyzed the outcomes of all bone marrow aspirations performed in children to confirm idiopathic thrombocytopenic purpura with typical laboratory features to see if any other diagnosis was found. In a similar fashion, the final diagnoses of all children who underwent bone marrow aspiration to confirm idiopathic thrombocytopenic purpura but who had abnormal laboratory features were also obtained.

During the time reviewed, 7,612 bone marrow aspirations were performed. Of these, 484 (6.4 percent) were performed to confirm a provisional diagnosis of idiopathic thrombocytopenic purpura. During the same 12-year period, 672 children were admitted to the institution with a primary diagnosis of acute idiopathic thrombocytopenic purpura. The study estimate indicated that 72 percent of children with idiopathic thrombocytopenic purpura underwent a bone marrow aspiration. Among 332 children with a platelet count of less than 50,000 x [10.sup.3] per [micro] L (50,000 x [sup.10.9] per L) but otherwise normal or typical hematologic parameters, no cases of leukemia were diagnosed. In the group of 135 children with atypical hematologic features for idiopathic thrombocytopenic purpura, three children were diagnosed with leukemia. All three of these children had at least two atypical hematologiC values in the complete blood cell count, and all had a clinical presentation not consistent with idiopathic thrombocytopenic purpura. Eight additional children in the group with atypical laboratory results were found to have aplastic anemia. The authors conclude that in children who present with thrombocytopenia and otherwise typical hematologic features of idiopathic thrombocytopenia--platelet count less than 50,000 x [sup.10.3] per [micro] L (50,000 x [10.sup.9] per L) with a normal hemoglobin, white blood cell count and neutrophil count--the risk of missing a diagnosis of leukemia is less than 1 percent. They also cite the significant cost of this procedure ($700 to $800) and associated morbidity, including pain, bleeding and infection.

JEFFREY T. KIRCHNER, D.O. Calpin C, et al. Is bone marrow aspiration needed in acute childhood idiopathic thrombocytopenic purpura to rule out leukemia? Arch Pediatr Adolesc Med April 1998; 152:345-7.

COPYRIGHT 1998 American Academy of Family Physicians
COPYRIGHT 2000 Gale Group

Return to Idiopathic thrombocytopenic purpura
Home Contact Resources Exchange Links ebay