Prolonged Prothrombin Time and Activated Partial Thromboplastin Time Due to Underfilled Specimen Tubes With 109 mmol/L (3.2%) Citrate Anticoagulant

Abstract

Underfilling of specimen tubes containing 129 mmol/L (3.8%) buffered citrate prolongs prothrombin time (PT) and activated partial thromboplastin time (APTT) values. We studied this phenomenon by using 109 mmol/L (3.2%) buffered citrate as the anticoagulant, anticipating some increase in tolerance to underfilling. Venous blood drawn from 12 healthy subjects and 30 patients receiving long-term oral warfarin therapy was mixed with 109 mmol/L buffered citrate solution in proportions equivalent to filling the collection tubes from 52% to 100% of capacity. Accurate PT values were obtained from normal specimens if the tubes were filled to 65% or more of capacity. Accurate PT results in the therapeutic range were obtained only with filling to 80% or more ofThe results of prothrombin time (FT) and activated partial thromboplastin time (APTT) tests are known to become prolonged if there is too high a concentration of citrate, as may occur if the specimen collection tube is insufficiently filled, and the proportion of whole blood to anticoagulant solution is less than 9:1. 1 -2 Guidelines based on this observation have been established in most clinical laboratories for the rrtiriimum acceptable volume of blood in specimen tubes submitted for coagulation tests. The National Committee for Clinical Laboratory Standards recommends a final citrate concentration of 10.9 to 12.9 mmol/L in the specimen, corresponding to complete filling of a tube containing one of the two common types of buffered citrate anticoagulant.

Diagnosis and Management of Noncardiac Complications in Adults With Congenital Heart Disease: A Scientific Statement From the American Heart Association

“…In patients with a hematocrit >55%, it is advisable that tubes with reduced sodium citrate be used to maintain a ratio of blood to anticoagulant of 9:1. [235][236][237] With appropriate citrate levels, laboratory testing includes platelet count, prothrombin time, and partial thromboplastin time.…”

The rare coagulation disorders – review with guidelines for management from the United Kingdom Haemophilia Centre Doctors' Organisation

“…Although 0.129 m trisodium citrate has been considered acceptable in the past [6] this is not currently recommended -the results of PT and APTT can be up to 10% longer in the higher strength anticoagulant depending on the reagents used [7]. The samples must be filled correctly, avoiding both under-and overfilling to give accurate results [8].…”

Anormal coagulation test results in the pediatric patient without the bleeding: A case report

“…Bazı çalışmalarda, yüksek hemotokrit değerlerine sahip örneklerde sitrat seviyelerinin yükselmesini simüle etmek için yetersiz doldurulmuş %3,2'lik ve %3,8'lik sitratlı tüp kullanmıştır. Bu çalışmalarda, hematokritin PZ ve aPTZ üzerine %3,8'lik sitratlı tüplerdeki beklenen etkinin çok daha fazla olduğunu gösterilmekle birlikte, her iki tüpte de anlamlı etki tespit edilmiştir (2)(3)(4)(5)(6) . Marlar ve ark.…”

“…Direkt ve indirekt yöntemlerle yapılan çalışmalara dayanarak, yüksek hematokrit değerine sahip kan örnekleri için kullanılan sitrat miktarının ayarlanması önerilmektedir (2)(3)(4)(5)(6) . Olgumuzda yüksek hematokritli çocuk hastanın koagülasyon testlerinde tanı ve tedaviyi etkileyebilecek değişiklikler literatür eşliğinde tartışılmıştır.…”