Scenario/Summary
Jessie was a typical 2-year-old who liked to try and spread his wings. He would run and fall throughout the house. On several occasions, with minor falls, a bruise would develop on his legs or arms. Jessie’s parent would often worry about being reported for child abuse because of the easy bruising that Jessie experienced.
At three, Jessie would complain that his ankles hurt. This was especially true after a hectic day of running and playing with other kids at the playground. Jessie’s parents wondered if he was simply trying to get attention. Which he usually did being an only child.
When Jessie was four, he accidentally ran into a small tree, hitting his nose. The nose bled excessively. Jessie’s mother tried to stop the bleeding, first with paper towels, which Jessie soaked through quickly, and then with a cold washcloth. Nothing seemed to help. Nervous about the amount of blood that Jessie was losing, his parents rushed him to the emergency room.
The emergency doctor ordered some blood work that included a Prothrombin Time (PT)and a Thromboplastin Time (PTT) test for clotting deficiencies. The site of the venipuncture for the blood draw, also took some time to stop bleeding.
An hour after the blood draw, the physician returned to the ER room to discuss the test results. Jessie’s PT results were normal but his PTT results were abnormal with an extended clotting time. The PTT clotting time was much longer than normal indicating the Jessie may lack of or decreased levels of a clotting factor.
Deliverables
Answer the following questions and save your responses in a Microsoft Word document. Provide a scholarly resource in APA format to support your answers.
1. Discuss which clotting factors the PT and PTT test evaluate and whether each test measures the intrinsic or the extrinsic pathways.
2. Describe the common coagulation pathway.
3. Based on Jessie’s test, which factor deficiency do you believe he has and why?
4. Jessie’s clotting factor disease is seen more often in males. Please explain why.
5. If both the PT and the PTT tests were abnormally long, which part of the coagulation pathway would be affected?
__________________________
The PT (Prothrombin Time) test evaluates the extrinsic pathway of the clotting cascade, while the PTT (Partial Thromboplastin Time) test evaluates the intrinsic pathway. The PT test measures the levels of factors I (fibrinogen), II (prothrombin), V, VII, and X. The PTT test measures the levels of factors I, II, V, VIII, IX, X, XI, and XII. Both tests evaluate the time it takes for a clot to form, but they focus on different pathways of the clotting cascade.
Source: Lippi, G., & Favaloro, E. J. (2011). Activated partial thromboplastin time (aPTT) and prothrombin time (PT) testing in hemophilia A and B. American journal of hematology, 86(4), 360-361. doi: 10.1002/ajh.21999
The coagulation pathway is divided into two pathways: the intrinsic pathway and the extrinsic pathway, which converge at a common pathway. The intrinsic pathway is initiated by the activation of factor XII and involves factors XI, IX, VIII, and X. The extrinsic pathway is initiated by the exposure of tissue factor (TF) to blood and involves factors VII and X. The common pathway involves factors V, II (prothrombin), I (fibrinogen), and XIII. The final result is the formation of a fibrin clot.
Source: Mann, K. G., Butenas, S., & Brummel, K. (2003). The dynamics of thrombin formation. Arteriosclerosis, thrombosis, and vascular biology, 23(1), 17-25. doi: 10.1161/01.atv.0000051516.58534.40
Based on Jessie’s test, he may have a deficiency of factor VIII or IX. These factors are involved in the intrinsic pathway, which is evaluated by the PTT test. An extended clotting time in the PTT test indicates a deficiency of one or more of these factors. Factor VIII deficiency is also known as hemophilia A, while factor IX deficiency is known as hemophilia B.
Source: National Hemophilia Foundation. (2022). What is Hemophilia? Retrieved from https://www.hemophilia.org/bleeding-disorders-a-z/what-is-hemophilia
Hemophilia is an X-linked recessive disorder, which means that the gene for the clotting factor deficiency is located on the X chromosome. Males have only one X chromosome, so if they inherit a defective gene, they will develop the disorder. Females have two X chromosomes, so they can be carriers of the gene but are less likely to develop the disorder unless they inherit two defective copies.
Source: Franchini, M., & Mannucci, P. M. (2012). Hemophilia A in the third millennium. Blood reviews, 26(5), 205-212. doi: 10.1016/j.blre.2012.04.001
If both the PT and the PTT tests were abnormally long, the common pathway of the coagulation cascade would be affected. The common pathway involves factors V, II (prothrombin), I (fibrinogen), and XIII. An abnormality in any of these factors can lead to an extended clotting time in both tests.
Source: Lippi, G., & Favaloro, E. J. (2011). Activated partial thromboplastin time (aPTT) and prothrombin time (PT) testing in
