The main methods of laboratory diagnostics of hemorrhagic syndromes

Tests for vascular - platelet factors. Tests for platelet factors include the quantitative platelet count, its morphology, platelet aggregation and adhesiveness tests, bleeding time test, estimation of platelet components in plasma.

Platelet aggregation test. An aggregating agent (activated thrombin, epinephrine, ADP, and collagen) is added to a suspension of platelet rich plasma and the response is measured in a spectrophotometer. Special devices called aggregometers are used to measure platelet aggregation.

Platelet adhesiveness test measures the ability of cells to adhere to glass surface. Adhesiveness can be determined by counting the number of platelet in the anticoagulated blood before they are passed through the column with glass beads, and by counting them again after they have passed through the column.

Bleeding time test measures time required for the cessation of bleeding after a standardized puncture through the skin 3 mm deep. The Duke test involves puncturing the earlobe with a lancet, drops of blood are blotted every 30 second and the time at which bleeding stops is noted. Normal limes for the Duke test are 1 to 3 minutes. The Ivy test have similar procedure but added a blood pressure cuff, which is placed on the upper arm and inflated to 40 mm Hg the skin is pieced with a lancet in the lower forearm. Blood is blotted every 30 second until the bleeding stops. Normal times for the Ivy test are between 2 and 6 minutes.

Tests for plasma factors involved in coagulation and fibrinolisis

Prothrombin time (PT) measures the extrinsic system (factor VII) as well as factors common in both systems (factor X, V, 11 and I). Prothrombin time test is performed by adding tissue extract (factor III = tissue factor) and calcium to the plasma. Normal prothrombin time - 10-17 second.

Activated partial thromboptastin time (APTT or PTTK. ) measures the intrinsic system's factors VIII, DC XI and XII, in addition to factors common to both systems. Three substances - phospholipid, a surface activator (Kaolin) and calcium arc added to the plasma. The normal PTTK. is 30-40 seconds.

Fibrinogen determinant test is performed by addition 0,2 ml thromboplastin and 0,1-0,5 % solution of calcium chloride to 1 ml platelet-rich plasma. Formed clot is dried and weighed. The normal fibrinogen levels in the blood are 200 to 400 mg per deciliter of plasma.

Thrombin time or fibrinogen deficiency test is performed by added the activated thrombin to blood plasma and measure the time in takes to form a clot The test reflects fibrinogen-fibrin conversion. Normal thrombin lime - 10-12 second.

HEMORRHAGIC SYNDROME

The bleeding disorders are a heterogeneous group of syndromes characterized by easy bruising and spontaneous bleeding from the blood vessels.

Classification:

/. Disorders of coagulation (coagulopathy) - hemophilia.

II. Disorders of platelets (thrombocytopenia) - Werlhoff's disease.

Ill Vascular disorders (vasopathy) Henoch-Schoenlein purpura.

 

HEMOPHILIA

Etiology

- congenital blood coagulation disorder;

- inheritance is sex linked, males are affected while females act as carrier;

- some cases do not have any family history and presumably result from spontaneous genetic mutations.

Pathogenesis

There are the major types of hemophilia: hemophilia A, hemophilia B (Chistmas disease) and hemophilia C.

Hemophilia A occurs as a result of low level or either absence of factor VIII, which primary synthesized by liver, but other organs such as the spleen. Kidney may also contribute to the plasma level. The factor VIII gene is localized on the X chromosome that is way the hemophilia A sex-linked disorder. All daughters of patient with hemophilia are obligate carriers and sisters have a 50%, chance of being a carrier. If a carrier has a son, he has a 50% chance of having hemophilia, and daughter has a 50% chance of being a carrier. 33% cases do not have family history. Lack of factor IX gene is known as hemophilia B (or Christmas' disease). Hemophilia C occurs in patients with lack of factor XI (Rosenthal syndrome).

Clinical feature

The main patients' complaints: spontaneous bleeding after trauma, dental extraction, surgery manipulation. Sometimes may be nasal, pulmonary hemorrhage and from gastrointestinal, genitourinary systems. The patient complains of the joint enlargement.

Objective examination. General patient's condition is usually satisfactory. In case of prolonged and recurrent hemorrhages and loss of large amount of blood general condition may be middle grave or grave. The posture of the patients is active with restriction due to the pain and walking difficulties in affected joints and muscles caused by spontaneous bleeding.

The color of the skin and visible mucosa as a rule is pallor, with hemorrhages lesions: petechia, ecchymoses and hematoma. Bleeding into the joints is known as hemarthrosis begin spontaneously without apparent trauma. The joints most commonly affected are knees, elbows, ankles and hips. Bone destruction occurs due to repeated subperioctal hemorrhages. The defects undergo neoossification causing expansion and pathological fractures in the bones. The deformities of joints and bones are specific signs of hemophilic patients. Muscle hemotomas are also characteristic of hemophilia secondary to hematomas appears atrophy of muscles. These occur most commonly in the calf and psoas muscles but they can arise in almost any muscle and cause the pressing on the nerve with consequent parasthesia and weakness in the extremities, progressive muscle and nerve damage resulting neuropathy. Hemophilic pseudotumours may occur in long bones, pelvis, ringers and toes.

The course of disease is characterized by early onset in babies about 6 months old, when superficial bruising or a hemarthrosis may occur. The spontaneous bleeding episodes, joint deformity and crippling are observed entire the patient life. Hematuria is more frequently than gastrointestinal bleeding. Intracranial hemorrhage is rare, but in severe and prompt case it may be fatal outcome. Operative and postoperative hemorrhage is dangerous.

Additional methods of examination

Clinical blood analysis:

- activated partial thromboplastin time increased;

- whole blood coagulation time is raised;

- factor VIII dolling assay (VIII C) reduced;

- immunological methods show normal VIII R, AG;

- bleeding time and prothrombin time tests normal;

- carrier females have half the clotting activity (VIII C) expected for the level of VIII R, G.

X-ray examination:

- broadening of femoral epicondyles;

- sclerosis, osteophyte and bony cists;

- atrophy of muscles.

The computer tomography scan: intracerebal hematoma.

HEMOPHILIA B (Christinas' disease)

Hemophilia B (Christinas disease) occurs as a result of a deficiency of factor IX. Like Hemophilia A it is also X-linked recessive trail. The clinical feature similar to the hemophilia A but bleeding is usually not as severe because factor IX is more stable than factor VIII C.

Additional methods of examination

Clinical blood analysis

- activated partial thromboplastin time is raised;

- whole blood clotting time (severe cases) is raised;

- factor IX clotting assay is reduced;

- both bleeding time and prothrombin time tests are normal.

HEMOPHILIA C

Hemophilia C - may be defined as a bleeding disease caused by a deficiency of factor XI. It is inherited as a recessive trait. The symptoms and signs are similar to other type of hemophilia.

IDIOPATHIC THROMBOCYTOPENIC PURPURA (Werlhoff's disease)

Thrombocytopenia is most common form of bleeding disorders due to the quantitative abnormalities of platelets. Because a number of platelets reduce in the blood stream, their function is impaired.

Etiology

Causes of decreased platelet production:

- selective megakaryocytic depression in bone marrow: drug-induced, chemicals.

Infiltration of bone marrow:

- aplastic anemia;

- leukemia;

- myelosclerosis;

- multiple myeloma;

- megaloblastic anemia;

- carcinoma.

Increased destruction of platelets:

- disseminated intravascular coagulation;

- idiopathic thrombocytopenic purpura;

- viral infections - Epstein-Barr virus, HIV;

- bacterial infections - septicemia.

Pathogenesis

Decreased platelet production result from three mechanisms: failure of megakaryocyte maturation, excessive platelet consumption or their sequestration in an enlarged spleen. The pathogenesis of idiopathic thrombocytopenic purpura is associated with activation of the immune system, production of the auto-antibodies, often directed against platelet membrane glycoprotein IIb-IIIa. Platelet destruction results from increased phagocytosis of antigen-antibodies immune complexes adhere to platelet by monocyte-macrophage system of the spleen and liver. The antibody covered platelets premature removal from the circulation. The reason for production of the antibody is unknown, thus this form of disease is defined as idiopathic.

Clinical feature

Idiopathic thrombocytopenic purpura more commonly affects females at an early age. The main complaints are easy bruising in skin and bleeding from mucosa with sudden onset after easy trauma and sometimes spontaneously. Very often symptoms are the bleeding from nose, gastrointestinal tract. lung and kidney hemorrhage, in women - menorrhagia. The course of disease is chronic, with remissions and relapses.

Objective examination. General patient's condition is satisfactory. If bleeding persists for more than some days resulted acute posthemorrhage anemia the patient's condition become grave and required immediately treatment. The main clinical signs are the presence features of skin bruising different size: petechiae, purpura and even hematoma, which located at the anterior part of trunk and extremities. According to the term of bruising appearance may be change of color with different tint: read, blue, green and yellow.

Skin bruising sometimes accompanied with profuse mucosa bleeding and become insidious character because occur posthemorrhage anemia. Spontaneous bleeding docs not usually occur until the platelet count falls below about 30x109/l.

Severe thrombocytopenia results in eye-ground hemorrhage, but intracranial hemorrhage is rare.

Splenomegaly is observered in about 10 % of the cases.