At a Glance Acquired high molecular weight kininogen (HK) deficiency is extremely rare. Antibody Baltimore is an antibody to factor XI that blocks high molecular weight kininogen binding and factor XIIa activation of factor XI (Blood 72:1748, 1988). It was associated with urinary tract bleeding. This antibody is to factor XI, not HK. Antibodies to…
At a Glance A patient with high molecular weight kininogen (HK) deficiency presents with a long activated partial thromboplastin time (APTT; >60 sec), normal prothrombin time (PT), and no history of bleeding. High molecular weight kininogen deficiency is quite rare; it is the least common of all the blood coagulation proteins deficiencies. In North America,…
At a Glance What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful? Acquired prekallikrein deficiency is very rare. It could arise from antibodies to the protein. There are few acquired inhibitors to prekallikrein reported. Its deficiency is not associated with bleeding. Test results consistent with acquired…
At a Glance Prekallikrein deficiency is a rare disorder seen in all ethnic groups. It is autosomal recessive in inheritance. It is associated with a mildly prolonged partial thromboplastin time (PTT) that will correct when incubated on the bench with all reagents for 1 hour. Its deficiency is not associated with bleeding. What Tests Should…
At a Glance Acquired factor XII deficiency is quite rare and is often not an isolated event. It is seen in sepsis, disseminated intravascular coagulation (DIC), or in patients with lupus anticoagulants who also have specific antibodies to factor XII. Very few acquired antibodies to factor XII have been reported. Spontaneous inhibitors to factor XII…
At a Glance The patient has a very long partial thromboplastin time (PTT) with a normal prothrombin time (PT) without a bleeding history. The patient had major surgery without bleeding. Factor XII deficiency is seen in individuals of Finnish or northern European extraction, but it has been recognized in all ethnic groups. It is autosomal…
At a Glance Inhibitors to factor XI have been reported. Most commonly, they are seen in factor XI deficient patients who have had bleeding and who have required previous fresh frozen plasma replacement. Spontaneous specific inhibitors to factor XI have been seen in patients with lupus anticoagulants. Inhibitors to factor XI promote bleeding, especially from…
At a Glance Factor XI deficiency is a bleeding disorder frequently associated with mucosal bleeding. It is autosomal recessive in inheritance. It is frequently seen in the Ashkenazi Jewish population of eastern European origin (~50% in the United States), but it has been associated with every ethnic group. It can be quite dormant in most…
