The third part of coagulation is tested clinically by the thrombin time, in which exogenous thrombin is added to plasma. The normal range of values is about 10-15 seconds; prolongations are observed in fibrinogen deficiency. This may be congenital, or due to acquired consumption of fibrinogen in disseminated intravascular coagulation (DIC), or may occur after administration of fibrinolytic drugs (see below). Treatment is with fresh frozen plasma or fibrinogen concentrates.
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| CLASSICAL HEMOPHILIA: CONGENITAL FACTOR VIII DEFICIENCY |
| A 3-year-old boy was admitted from the Emergency Room of his local hospital because of extensive bruising after a fall down a few stairs (see Fig. 6.5). A routine coagulation screen test showed a greatly prolonged APTT of more than 150 seconds (normal range, 30-50 seconds). Assay of coagulation factor VIII showed a very low level; the vWF level was normal. His mother recollected a family history of excessive bleeding which had affected her brother and father. |
| Comment. Because of this typical history of an X-linked recessive bleeding disorder, a low coagulation factor VIII level, and a normal vWF level, a diagnosis of classical hemophilia (congenital factor VIII deficiency) was made. The family were referred to the local Hemophilia Center and counseled about the risks of further affected sons and carrier daughters. The child was treated with intravenous factor VIII concentrate for the presenting bleed, and for future bleeds, injuries, or surgery. |
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