eMedicine Specialties > Neurology > Neuro-vascular Diseases
Blood Dyscrasias and Stroke: Differential Diagnoses & Workup
Updated: Jul 14, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Differential Diagnoses
Other Problems to Be Considered
Transient ischemic attacks
Carotid disease and stroke
Workup
Laboratory Studies
- Laboratory tests recommended for all patients in whom a hypercoagulable state is suspected include the following:
- Prothrombin time (PT) is used to diagnose deficiencies or inhibitors of factors I, II, V, VII, and X. It also is used to monitor warfarin therapy and screen for vitamin K deficiency. It usually is expressed in terms of a standardized international normalized ratio (INR).
- Partial thromboplastin time (aPTT) is used to diagnose deficiencies or inhibitors of factors VIII, IX, XI, and XII, and to diagnose deficiency of von Willebrand factor. It also is used to monitor heparin therapy and as a screening test for LA.
- The following tests are optional and should be done if a specific hypercoagulable state is suspected:
- Thrombin time is used to diagnose fibrinogen deficiencies, to detect heparin resistance, and to monitor fibrinolytic therapy.
- aPL of the immunoglobulin G (IgG) class and LA are tested in patients with or without clinical lupus in whom hypercoagulability is suspected. These include patients with stroke who have a history of thrombocytopenia, fetal loss, dementia, optic change, and recurrent venous thrombosis.
- Protein C activity is used to screen for protein C deficiency or to diagnose protein C deficiency secondary to dysproteinemia. Hereditary heterozygous protein C deficiency is associated with recurrent venous thrombosis. To confirm protein C deficiency and to differentiate it from dysproteinemia, the protein C antigen is measured. Protein C deficiency is noted in liver disease, disseminated intravascular coagulation (DIC), vitamin K deficiency, and warfarin therapy.
- Protein S acts as a cofactor of protein C. Protein S activity is used to screen for protein S deficiency or to diagnose the presence of a dysfunctional protein. Hereditary heterozygous protein S deficiency is associated with recurrent venous thrombosis. To confirm protein S deficiency and to differentiate it from dysproteinemia, the protein S antigen is measured. Protein S deficiency is noted following acute thrombotic events; in liver disease, DIC, vitamin K deficiency, warfarin therapy, l-asparaginase therapy, and pregnancy; and with oral contraceptives.
- Antithrombin III is an inhibitor of thrombin. Antithrombin III activity is used to screen for antithrombin III deficiency or to diagnose dysfunctional antithrombin III. Hereditary heterozygous antithrombin III deficiency is associated with recurrent venous or arterial thrombosis. To confirm antithrombin III deficiency and to differentiate it from dysproteinemia, the antithrombin III antigen is measured. Antithrombin III deficiency is noted following acute thrombotic events or surgery; in liver disease, nephrotic syndrome, DIC, heparin therapy, l-asparaginase therapy, and pregnancy; and with oral contraceptives.
- Resistance to APC is the most common inherited risk factor for thrombosis. It may be tested on plasma from patients on heparin or warfarin. A value <2.2 indicates a high likelihood of APC resistance, and DNA-based testing for factor V Leiden then should be performed. Testing for factor V Leiden is not confirmation of the fact that APC resistance is expressed.
- Fasting homocysteine level is measured most commonly by high-performance liquid chromatography (HPLC) with fluorescence detection. Hyperhomocystinemia is associated with arterial and venous thrombosis and is to be distinguished from autosomal recessive homocystinuria. Elevated homocysteine levels are encountered in the elderly; in patients with nutritional deficiency of vitamin B-6, B-12, or folate; and in renal insufficiency and other disorders.
- Lp(a) is an atherogenic molecule. High levels of Lp(a) have been correlated with atherosclerosis of the cerebral and other vasculature.
- Hemoglobin electrophoresis enables detection of hemoglobin SS and SC, both of which are risk factors for arterial strokes. The test should be ordered in African Americans and others whose ethnicity puts them at particular risk of sickle cell anemia. Although sickle cell disease itself does not alter hemostasis, it currently is believed to be a risk factor for stroke by vascular damage.
Imaging Studies
The following studies may be helpful in assessment of suspected stroke or stroke risk:
- MRI of the brain (T1-, T2-, and diffusion-weighted images)
- Magnetic resonance angiogram or computed tomography angiogram in cases of arterial stroke
- Magnetic resonance venogram if cerebral venous thrombosis is suspected
- Transcranial Doppler ultrasonography to assess stroke risk in sickle cell anemia6,7
- This is most useful in children, as it allows detection of increases in mean blood velocities within the circle of Willis and middle cerebral artery as the arteriopathy of sickle cell disease develops.
- It is also helpful in the assessment of intracranial arterial stenosis or occlusion.
- Carotid ultrasonography if extracranial stenosis or occlusion is suspected
- Cerebral angiogram if noninvasive tests yield inconclusive results
More on Blood Dyscrasias and Stroke |
| Overview: Blood Dyscrasias and Stroke |
 Differential Diagnoses & Workup: Blood Dyscrasias and Stroke |
| Treatment & Medication: Blood Dyscrasias and Stroke |
| Follow-up: Blood Dyscrasias and Stroke |
| References |
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Further Reading
Keywords
hypercoagulable state, cerebrovascular event, cerebrovascular accident, coagulation disorder
