J Clin Pathol Qual Control.  1997 Dec;19(2):297-301.

Observations of Prothrombin Time and Activated Partial Thromboplastin Time According to Various Conditioned Specimen

• Keum DG
• Kim WS
• Choi JW

Abstract

BACKGROUND: Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are widely used for screening coagulation disorders in most clinical laboratories. PT and aPTT are not completely identified in significant variabilities of routine screening tests. This study was made to observe in more detail some variables known to affect PT and aPTT coagulation tests.
METHODS
Thirty specimens of healthy human blood were collected in three tubes containing 0.3 mL of 3.8% sodium citrate ; centrifuged at 2400 rpm for 15 minutes, under separated or not separated plasma after centrifugation and then put on room temperature of refrigerator each until ready for use. PT and aPTT tests were performed every 1 hr, 2 hrs, 3 hrs, 4 hrs, 6 hrs, 12 hrs and 24 hrs after blood collection compared with one's obtained immediately by coagulometer.
RESULTS
Studies of the stability of these specimens indicate that specimens (except separated plasma specimens tested at room temperature, P<0.05) do not noticeably deteriorate for as long as 12 hours (P>0.05) even when kept at both temperature in PT and aPTT coagulation tests.
CONCLUSIONS
On the basis of this study, it is proposed that results of both PT and aPTT coagulation tests in practice are not changed until 12 hours at room temperature after blood collection.

MeSH Terms

Centrifugation
Citric Acid
Humans
Mass Screening
Partial Thromboplastin Time*
Plasma
Prothrombin Time*
Prothrombin*
Sodium
Citric Acid
Prothrombin
Sodium