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Physical Examinations And Laboratory Investigations In Diagnosing Idiopathic Thrombocytopenic Purpura

Updated on February 3, 2014

Lab Investigations On ITP

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Laboratory Investigations

Physical examination reveals the typical purpuric spots and ecchymoses, particularly over the limbs, chest and sometimes over the neck. Areas of pressure by clothing or minor trauma of rubbing as in the axillae and thighs show more purpuric spots spontaneous bleeding is seen from the mouth, nose, urinary tract and genital tract in women. In severe cases, hemorrhagic bullae develop in the mucous membrane of the mouth. The extravasated blood clots. Hematemesis and melena may occur. Ordinarily, the bleeding stops within a few days either spontaneously or with treatment. Retinal bleeding occurs in severe cases. Bleeding into the central nervous system may present as spontaneous subarachnoid hemorrhage or cerebral hemorrhages. The spleen may be just palpable in 10% of cases, in any case, there is no marked splenomegaly.

Laboratory investigations

Platelet count is reduced in all cases. It may be below 20,000 per cmm in severe cases. Under light microscopy, the platelets appear normal, except for a few large forms- the megathrombocytes. The presence of megathrombocytes indicates disordered thrombopoiesis. Though there is no gross impairment of platelet function, the antibody leads to impairment of platelet release reaction which can be demonstrated in vitro. The hemorrhagic manifestation is mainly due to thrombocytopenia, and it is aggravated by the dysfunction as well. Bleeding time is prolonged whereas the whole blood clotting time is normal. Clot retraction is deficient if the platelet count is below 50,000/cmm. Hess test is positive. Examination of the bone marrow shows increased number of megakaryocytes and many of them do not show budding activity. In over 75% of cases, antiplatelet antibodies can be demonstrated by direct or indirect tests. The degree of anemia is proportional to the blood loss.

Purpuric Lesions On A Patient

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Diagnosis And prognosis

Differential diagnosis

This includes allergic purpura, drug induced thrombocytopenia, systemic lupus erythematosus, acute leukemias, aplastic anemia, thrombocytopathies, vascular disorders and septicemias. Systemic lupus erythematosus may clinically present as thrombocytopenic purpura for a considerable period of time before other florid features develop. Presence of mild or moderate splenomegaly should suggest the possibility of acute leukemia, lupus erythematosus or hemolytic anemia. Sometimes ITP may be associated with other autoimmune disorders such as hemolytic anemia (Evan’s syndrome).

Course and prognosis

Acute ITP runs a short course and may remit spontaneously. It may result in serious bleeding with rapid development of anemia. Fulminant cases may be fatal if untreated. Death is due to severe blood loss or bleeding into vital organs such as the brain. Platelet counts below 10,000/cmm, hematuria, signs of meningeal irritation are grave prognostic signs. Mortality is about 3-5% in large series.

Of the acuta ITP cases, 7-28% go into the chronic form. In the chronic form periods of remissions and exacerbations alternate and the patient suffers only minor disability. Infections, menstruation, or drugs like aspirin may precipitate bleeding episodes. Menstrual and intermenstrual blood loss in women may be severe and even life-threatening and they seek medical help earlier due to this factor. During pregnancy, the bleeding episodes may aggravate in many cases, though in some cases, the condition may remit. Risk of intra-uterine death of fetus and perinatal fetal loss are high.

© 2014 Funom Theophilus Makama

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