Idiopathic thrombocytopenic purpura laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
==Laboratory Findings== | ==Laboratory Findings== | ||
The diagnosis of ITP is a diagnosis of exclusion. First, one has to make sure that there are no other blood abnormalities except for low platelet count and no physical signs except for signs of bleeding. Then, the secondary causes (usually 5-10% of suspected ITP cases) should be excluded. Secondary causes could be [[leukemia]], medications (e.g. [[quinine]], [[heparin]]), [[lupus erythematosus]], [[cirrhosis]], [[HIV]], [[hepatitis]] C, congenital causes, [[antiphospholipid syndrome]], [[von Willebrand factor]] deficiency and others.<ref name="pmid15941913"/><ref name="pmid15660520"/> | |||
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. | |||
Bleeding time is prolonged in ITP patients; however, the use of bleeding time in diagnosis is discouraged by the American Society of Hematology practice guidelines<ref name="pmid9036806">{{cite journal |author= |title=Diagnosis and treatment of idiopathic thrombocytopenic purpura: recommendations of the American Society of Hematology. The American Society of Hematology ITP Practice Guideline Panel |journal=Ann. Intern. Med. |volume=126 |issue=4 |pages=319-26 |year=1997 |pmid=9036806 |doi=}}</ref> as useless. For example the [[BMJ]] review of the basics of hematology states: "The bleeding time may or may not be prolonged in congenital or acquired platelet dysfunction, and therefore a normal bleeding time does not exclude these conditions."<ref name="pmid9081003">{{cite journal |author=Liesner RJ, Machin SJ |title=ABC of clinical haematology. Platelet disorders |journal=BMJ |volume=314 |issue=7083 |pages=809-12 |year=1997 |pmid=9081003 |doi=}}</ref> | |||
Platelet-associated [[antibody]] (IgG), which was the standard test of past years, is not now considered mandatory to diagnose ITP. Test for platelet antibody are not helpful as both their [[sensitivity]] and [[specificity]] are limited. | Platelet-associated [[antibody]] (IgG), which was the standard test of past years, is not now considered mandatory to diagnose ITP. Test for platelet antibody are not helpful as both their [[sensitivity]] and [[specificity]] are limited. | ||
==References== | ==References== | ||
Revision as of 15:10, 21 September 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
The diagnosis of ITP is a diagnosis of exclusion. First, one has to make sure that there are no other blood abnormalities except for low platelet count and no physical signs except for signs of bleeding. Then, the secondary causes (usually 5-10% of suspected ITP cases) should be excluded. Secondary causes could be leukemia, medications (e.g. quinine, heparin), lupus erythematosus, cirrhosis, HIV, hepatitis C, congenital causes, antiphospholipid syndrome, von Willebrand factor deficiency and others.[1][2]
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.
Bleeding time is prolonged in ITP patients; however, the use of bleeding time in diagnosis is discouraged by the American Society of Hematology practice guidelines[3] as useless. For example the BMJ review of the basics of hematology states: "The bleeding time may or may not be prolonged in congenital or acquired platelet dysfunction, and therefore a normal bleeding time does not exclude these conditions."[4]
Platelet-associated antibody (IgG), which was the standard test of past years, is not now considered mandatory to diagnose ITP. Test for platelet antibody are not helpful as both their sensitivity and specificity are limited.
References
- ↑
- ↑
- ↑ "Diagnosis and treatment of idiopathic thrombocytopenic purpura: recommendations of the American Society of Hematology. The American Society of Hematology ITP Practice Guideline Panel". Ann. Intern. Med. 126 (4): 319–26. 1997. PMID 9036806.
- ↑ Liesner RJ, Machin SJ (1997). "ABC of clinical haematology. Platelet disorders". BMJ. 314 (7083): 809–12. PMID 9081003.