LabMed

Prekallikrein Deficiency – Congenital

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 I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Test results consistent with a diagnosis of prekallikrein deficiency include PTT 35-45 sec and a low value for a plasma prekallikrein assay (coagulant or chromogenic).(Table 1)

Table 1

Test Results Indicative of the Disorder
APTT Plasma Prekallikrein Assay
35-45 sec <10%

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications - OTC drugs or Herbals - that might affect the lab results?

Anticoagulants that interfere with clot-based assay, such as unfractionated heparin, enoxaparin, argatroban, bivalirudin, hirudin, and dabigatran, will interfere with laboratory results.

What Lab Results Are Absolutely Confirmatory?

Low prekallikrein assay with no evidence for a defect in other intrinsic coagulation factors and no lupus anticoagulant is absolutely confirmatory.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

Low prekallikrein assay without evidence for an inhibitor to plasma prekallikrein should be requested.

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