DIAGNOSES AND DISCUSSION OF CHALLENGING CLINICAL CASE NO. 07/2001
| Factor
XIII deficiency may be inherited or acquited and frequently causes severe
bleeding problems. In this disorder, the bleeding time, prothrombin time,
and partial thromboplastin time (PTI) are all normal. The screening test
for factor XIII deficiency is a clot solubility assay. Persons with
deficiencies of factor XIII (Hageman factor) or prekallikrein often have
dramatic prolongations of the PTT, but do not have bleeding problemss even
with surgery or trauma. The presence of a normal bleeding time excludes
trhombasthenia, an ubgeruted disorder in which there is defective platelet
aggregation in response to agonists that require fiubrinogen binding, such
as adenosine diphosphate, thrombin, or epinephrine. Protein S is a vitamin
K-dependent plasma protein and a cofactor for the expression of the
anticoagulant activity of activated protein C. Familial protein S.
deficiency is associated with a thrombotic disthesis. |