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Specimen Requirements Printable Version

Tests Explained Printable Version

 

Tests Explained

 

Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT)

 

Prothrombin Time (PT) measures the extrinsic pathway of coagulation following damage to blood vessels. Activated Partial Thromboplastin Time (aPTT) measures the intrinsic pathway of coagulation.

 

Both these tests are done in tandem and help determine the variety of factors involved in the normal blood clotting process and the pathway involved. Clotting factor disorders result either in longer clotting time and hemorrhage, or excessive clotting with thrombosis and micro emboli. Deficiencies have been associated with failed embryo implantations and recurrent pregnancy loss.

 

Clotting Factors (proteins essential for normal blood clotting)

 

Lupus Anticoagulant

 

Lupus is a systemic autoimmune disease that mainly affects women of non-European descent, where the body attacks its own cells. One component of the disease is a specific type of anti-phospholipid antibody in the bloodstream that can cause abnormal blood clotting. Lupus anticoagulant testing is used to help determine the cause of unexplained blood clotting and/ or recurrent pregnancy loss.

 

Anti-Phospholipid Antibodies (APA)

 

Phospholipids are a main component of the cell membrane. Antibodies against phospholipids in the blood attach to the cell membrane. Positive APA is an autoimmune disorder that results in an increased blood clotting tendency that can cut off blood flow to the fetus. These antibodies can also cause the placenta to have a weak attachment to the uterine lining and may cause recurrent miscarriages.

 

Cardiolipin is a phospholipid, a main component of cell membranes. It is essential for proper cell functions necessary for embryo development. Elevated levels of antibodies to cardiolipin are an autoimmune disorder that may interfere with the ability of cells to function normally, and have been associated with venous and/or arterial thrombosis (clotting), lower counts of blood platelets, and fetal loss.

 

We test for 2 different forms of antibodies (IgM, and IgG) against the most common APA: anti-phosphatidylserine, anti-cardiolipin, and anti-β2 glucoprotein antibodies. Next in significance are anti- phosphatidylethanolamine, anti-phosphatidylinositol, anti-prothombin, and anti-annexin antibodies followed by other less common antibodies such as anti-phosphatidic acid and anti-phosphatidylglycerol antibodies.

 

Anti-phosphatidylserine Antibodies (IgG & IgM)

Anti-phosphatidic Acid Antibodies (IgG & IgM)

Anti-phosphatidylglycerol Antibodies (IgG & IgM)

Anti-phosphatidylinositol Antibodies (IgG, IgM)

Anti-phosphatidylethanolamine Antibodies (IgG, IgM)

Anti-phosphatidylcholine Antibodies (IgG, IgM)

Anti-prothombin Antibodies (IgG, IgM)

Anti-annexin Antibodies (IgG, IgM)

Anti- β2 glucoprotein Antibodies (IgG, IgM)

Anti-cardiolipin Antibodies (IgG, IgM)

 

 

Genetic Tests

 

Thrombophilia  panel: (Total 10 genetic Loci)

 

Prothrombin is a protein circulating in the blood essential for clotting. A mutation in the Prothrombin gene results in excess production of the prothrombin protein with the result that the blood may over clot. Mutations in this gene may lead to recurrent pregnancy loss, fetal death and pre-eclampsia. It may also result in placental abruption; the abnormal separation of the placenta after 20 weeks of gestation andprior to birth, where the placental lining separates from the uterus of the mother. It is the most common cause of late pregnancy bleeding.

Antithrombin is a protein in the blood that blocks the formation of blood clots by inhibiting the procoagulation (causing the blood to clot) factors II, IX, X and XI. It is an inherited condition in which an abnormal gene (inherited from a parent with the disease) leads to low levels or reduced function of the protein. This can cause abnormal blood clotting.

Factor V Leiden. Factor V is a protein essential for normal blood clotting. Once the blood has sufficiently clotted, the Factor V Leiden protein becomes inactivated. Some people inherit a defective Factor V gene, Factor V Leiden (a point mutation). This genetic defect makes the Factor V Leiden protein much more difficult to inactivate, resulting in excessive clotting. The Factor V Leiden defect has been associated with recurrent pregnancy loss, late abortions, fetal death/growth retardation and pregnancy complications such as pre-eclampsia.

Factor XIII is a protein that is part of the cascade of clotting factors involved in the process of forming a protective blood clot. Genetic variations in the gene for the Factor XIII protein have been associated with an increased ability to form a blood clot. Women who are homozygous for Factor XIII mutations also have a high risk for recurrent spontaneous abortion.

MTHFR is a recessive gene that when it carries one or more mutations, may lead to accumulation of high levels of homocysteine subsequently promoting thrombophilia. Both alleles of the MTHFR gene (homozygous mutant) need to have the mutation in order to have a noticeable effect. Mutations of the MTHFR gene are associated with a higher risk for recurrent abortions and birth defects. It may also lead to third trimester and post-partum complications.

Plasminogen Activator Inhibitor – 1 (PAI-1). Plasminogen activator is an enzyme involved in the process of breaking down blood clots. Elevated levels of this enzyme (the inhibitor for plasminogen activator) cause excessive clotting as breaking down

blood clots is blocked. Abnormal levels of PAI-1 may cause recurrent pregnancy loss, pre-eclampsia, fetal growth retardation and fetal death.

Human platelet antigens (HPA1) can stimulate production of alloantibodies (antibodies against other people's antigens) in recipients of transfused platelets from donors with different HPAs. These antibodies cause neonatal alloimmune thrombocytopenia which is a disease that affects fetuses and newborns. Genetic differences between the fetus and mother may result in the expression of certain antigens by fetal platelets not expressed by the mother. Feto-maternal transfusions result in the recognition of these antigens by the mother's immune system as non-self, with the subsequent generation of allo-reactive antibodies which cross the placenta. Thrombocytopenia is mild, the affected neonates remain largely asymptomatic and no intervention is needed. Cases of severe neonatal thrombocytopenia may exhibit hemorrhagic complication at or a few hours after delivery. The most serious complication is intracranial hemorrhage, leading to death in approximately 10%, or neurologic complications in 20% of cases.

APO-E gene provides instructions for making apolipoprotein E which combines with lipids in the body to form lipoproteins.

Lipoproteins are responsible for packaging cholesterol and other fats and carrying them through blood stream. Maintaining normal level of cholesterol is essential for prevention of cardiovascular disorder. There are at least three slightly different alleles of APO-E gene called e2, e3, & e4. Most common is e3, e4 is associated with recurrent pregnancy loss.