Prolonged Prothrombin Time (PT): definition Posted by: Cleo Libonati, RN, BSN in DICTIONARY 0 2,428 Views A blood test result showing that blood clots too slowly due to vitamin K deficiency. It is an atypical symptom of celiac disease. Click for full description. Abnormal Clotting Atypical Symptom of Celiac Disease Blood Plasma Disorders Excessive Bleeding Glossary. Malabsorption Malnutrition Prolonged Prothrombin Time (PT) PT Out of Proportion to PTT System - Blood Vitamin K Deficiency 2013-04-13 Cleo Libonati, RN, BSN