Clinical Manifestations Of Secondary Thromobocytopenia And Thrombocytopathies
Secondary Thrombocytopenia Manifestations
Thrombocytopenia may develop as a secondary manifestation of different disorders such as acute leukemia, aplastic anemia or systemic lupus erythematosus. The clinical manifestations depend upon the underlying cause.
In drug-induced thrombocytopenias, very often other signs of drug toxicity may be evident but thrombocytopenia may be the sole manifestation at times. The drug or its metabolites act as haptens which bind noncovalently with albumin or other serum proteins in the plasma to form complete antigens. Antibodies are produced which combine specifically with the protein-bound haptenic drug or its metabolites to form antigen-antibody complexes. These are adsorbed on to the platelet surface. They activate complement and this leads to complement-mediated lysis of platelets in the circulation. If the amount of antibody coating the platelets is small, such platelets are destroyed by the macrophages of the spleen and liver. Drug induced thrombocytopenia is generally severe. Since presence of the drug or its metabolites is essential to perpetuate the immune mechanisms, withdrawal of the drug relieves the thrombocytopenia promptly. In severe cases, platelet transfusions are required. Corticosteroids help in arresting platelet destruction by inhibiting macrophage function in the spleen and liver.
Manifestations Of Thrombocytopathies
These are conditions associated with functional defects of platelets. Platelet number may be normal or even increased. The defects may be either hereditary or acquired. Among the hereditary types ‘storage pool’ disease and hereditary thrombasthenia are important. There are several other disorders included under this group but they are rare.
Acquired dysfunction of platelets occurs as a result of therapy with aspirin, phenylbutazone, indomethacin, other nonsteroidal anti-inflammatory drugs, dextran, clofibrate, dipyridamole, sulfinpyrazone, cyproheptadine and large doses of penicillins. Alcohol inhibits platelet function if taken in large doses. These may be clinically insignificant in otherwise normal individuals but the bleeding tendency is aggravated in the presence of underlying hemorrhagic disorders. A single dose of Aspirin may produce platelet dysfunction which may last up to five days.
Other causes of acquired thrombocytopathy are uremia, hepatic failure, paraproteinemias such as myelomatosis and macroglobulinemia and nutritional disorders like scurvy.
Storage Pool disease
This is an autosomal dominant disorder in which the stores of ADP in the granules or the platelets are absent and so ADP is not released for further aggregation and platelet functions.
Hereditary Thrombasthenia (Glanzmann’s Disease)
This is a rare autosomal recessive disorder occurring in both sexes. Bleeding manifestations are purpura, epistaxis, bleeding from cuts and wounds, menorrhagia and excessive bleeding during delivery. The characteristic laboratory finding is the failure of platelets to aggregate in the presence of ADP, adrenaline, noradrenaline, thrombin, or 5- hydroxytryptamine. Platelet adhesion and clot retraction are poor. Bleeding manifestations are usually mild. Severe cases may necessitate replacement of blood or normal platelets.
Secondary thrombocytopenia and thrombocytopathies are of huge significance in recent medicine as they are beginning to increase in occurrence and as well becoming fatal if not properly taken care of.
© 2014 Funom Theophilus Makama