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NNL
Awaitin The Unexpected  Topics: 779 Posts: 6613 |
A 25-year-old woman presents with a history of losing four pregnancies in the past 5 years. She also has a history of recurrent pains in her legs secondary to recurrent thrombosis. Her symptoms are most likely due to a deficiency of which one of the following substances? A. PA inhibitors B. Protein C C. Plasmin D. Thrombin E. C’1 inactivator
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GoodGirl
| . Topics: 154 Posts: 2516
B
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a3112
| Forum Junior Topics: 51 Posts: 1094
B
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SILVER
| DoWhatYouGotToDo!  Topics: 56 Posts: 1289
B
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Karime
| Sun and Shield  Topics: 27 Posts: 2493
b
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keepgoing
| .....  Topics: 109 Posts: 1865
B
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NNL
| Awaitin The Unexpected Topics: 779 Posts: 6613
GoodGirl wrote: B 
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NNL
| Awaitin The Unexpected Topics: 779 Posts: 6613
The answer is b. Two important control points of the coagulation cascade are the fibrinolytic system and certain plasma protease inhibitors. The main component of the fibrinolytic system is Plasmin, which is converted from plasminogen by either factor XII or a plasminogen activator (PA). Examples of PAs include tissue plasminogen activator (tPA), urokinase plasminogen activator, and streptokinase. Once formed, Plasmin splits fibrin and also degrades both fibrinogen and coagulation factors VIII and V. Plasma protease inhibitors include antithrombin III and protein C. Antithrombin III in the presence of heparin inhibits thrombin, XIIa, XIa, Xa, and IXa, while protein C inhibits Va and VIIIa. The significance of these control mechanisms is illustrated by the fact that abnormalities of these systems, such as deficiencies of antithrombin III, protein C, or protein S, are associated with hypercoagulable states and increased risk of thrombosis, as the main factors leading to thrombosis include injury to endothelium, alterations in blood flow, and hypercoagulability of the blood. Hypercoagulability may be a primary (genetic) or secondary abnormality. Primary hypercoagulable states include the previously mentioned deficiencies of antithrombin III, protein C, or protein S. These deficiencies are associated with recurrent thromboembolism in early adult life and recurrent spontaneous abortions in women. The causes of secondary hypercoagulable states are numerous and include severe trauma, burns, disseminated cancer, and pregnancy. Lower risk factors for the development of secondary hypercoagulable states include age, smoking, and obesity. Some patients with high titers of autoantibodies against anionic phospholipids such as cardiolipin (the antibody being called a lupus anticoagulant) have a high frequency of arterial and venous thrombosis. To summarize, it is important to remember that the differential diagnosis of recurrent spontaneous abortions in women includes deficiencies of protein C and protein S, and the presence of the lupus anticoagulant, which is part of the antiphospholipid syndrome.
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