Coagulation Pathway Disorders MCQs

PT is the standard test for monitoring treatment with oral anticoagulant (warfarin) inhibit carboxylation of vitamin K dependent factors (Factor II, VII, IX and X) and make these factors inactive. In a patients receiving oral anticoagulants, PT should be reported as a ratio of PT of patient to PT of control; it should not be reported as percentage. Various types of thromboplastin reagents obtained from different sources (like ox brain, rabbit brain, rabbit lung) are available commercially for PT test. Reference : Essentials of clinical pathology, 2nd edition ,page number - 332

The degradation of cellular proteins occurs mainly by ubiquitin proteosome pathway. Nutrient deficiency and disuse may activate ubiquitin ligases, which attach the small peptide ubiquitin to cellular proteins for degradation in proteasomes. This pathway is thought to be responsible for various catabolic conditions. Reference: Robbins and Cotran Pathologic Basis of Diseases, 19 th ed Pg:37

Factor V Leiden mutation results in glutamine to arginine substitution at amino acid residue 506 that renders factor V resistant to cleavage and inactivation by protein C. As a result, an important antithrombotic counterregulatory pathway is lost and chances of thrombosis are highly raised Reference : Robbins 9th/pg 123

This girl has features of hemophilia A. This X-linked recessive condition is expected to occur in males who inherit the one maternal X chromosome with the genetic mutation, and they do not have another X chromosome with a normal functional allele, as is the case in her brother. Hemophilia in a female can be explained by the Lyon hypothesis, which states that only one X chromosome in a female is active (the “turned off” X chromosome is the Barr body) for most genes, but this inactivation is a random event. Some unlucky females are out on the tail end of the Poisson distribution of random events and have few active X chromosomes with the normal allele, leading to markedly diminished factor VIII activity. The other choices do not explain this phenomenon. Reference: Robins Basic Pathology 10th ed/pg 267

Two types of DIC are acute (decompensated and chronic compensated). In acute DIC, there is rapid activation of coagulation leading to bleeding from consumption of coagulation factors. Findings in acute DIC are low platelet, prolonged PT and APTT, low fibrinogen, and increased FDP and D-dimer. In chronic DIC, there is slow activation of coagulation with slow consumption of coagulation factors. Findings are normal platelet count, normal PT and APTT. However, FDP and D-dimer are increased. So in acute DIC, all the four options are correct, while if we consider the question as chronic DIC, then best possible answer is increased FDP. Reference: Robbins & cotran pathologic basis of diseases 10 th edition, Chapter 14, pg 667

About use of Heparin in DIC: Low doses of continuous infusion heparin (5-10 U/ kg per h) may be effective in patients with low-grade DIC associated with solid tumor, acute promyelocytic leukemia, or in a setting with recognized thrombosis. Heparin is also indicated for the treatment of purpura fulminans during the surgical resection of giant hemangiomas and during removal of a dead fetus. In acute DIC, the use of heparin is likely to aggravate bleeding. To date, the use of heparin in patients with severe DIC has no proven survival benefit. Reference : Robbins 9th/pg 662; 8th/pg 672

Deficiency of factor 12 doesnot cause bleeding Reference: Robin's basic pathology 10 th edition, 120

Abnormal bleeding manifests shortly after birth, when bleeding from the healthy umbilical cord remnant occurs. Umbilical stump bleeding is an uncommon presentation for other congenital bleeding disorders. Rebleeding at circumcision is also common. The most life-threatening complication of factor XIII deficiency is spontaneous intracranial hemorrhage. Reference : Robbins 9th/pg 662