PROTEIN-Z DEFICIENCY - A NEW CAUSE OF BLEEDING TENDENCY

Protein Z is a vitamin K-dependent plasma protein synthesized by the l iver. Protein Z promotes the association of thrombin with phospholipid surfaces. So far, nothing is known about the clinical relevance of pr otein Z except alterations measured in patients under oral anticoagula nt treatment. We propose that in protein Z deficiency a bleeding tende ncy might result because of the interaction of protein Z with thrombin on phospholipid endothelial surfaces. Therefore, we examined 36 patie nts with bleeding tendency of unknown origin, who were not under oral anticoagulant treatment and had normal liver synthesis function. Mean protein Z value of the patients with bleeding tendency was significant ly diminished in comparison to the healthy control group. Twenty-one o f the bleeding patients had lower protein Z levels than the lowest pro tein Z level of the control group. In conclusion, protein Z deficiency is described as a new type of bleeding tendency.