Objective: To determine the optimum storage temperature and time for prothrombin time and activated partial thromboplastin time at various intervals at both room temperature and refrigerator.
Study design: Experimental study.
Place and duration of study: Advanced Medical and Dental Institute (AMDI), Laboratory at University Sains Malaysia (USM), from August 2009 to June 2010.
Methodology: After obtaining the consent, 33 blood samples were collected from AMDI staffs and students. Prothrombin time (PT) was measured at 0, 4, 8 and 24 hours (h). Partial thromboplastin time (APTT) was measured at 0, 2, 6 and 8 h both at room temperature (RT) and refrigerator.
Results: Thirty three subjects (14 males and 19 females, aged from 20 to 40 years) were involved. PT showed no significant differences at RT at 4 h, while significant differences after 8 h and 24 h at RT and after 4 h, 8 h and 24 h at refrigerator were observed. APTT showed no statistically significant differences at 2 h but showed significant differences at 6 h, 8 h at both RT and refrigerator.
Conclusion: Samples for PT testing can be accepted only up to 4 h when kept at RT while the samples cannot be accepted when kept at refrigerator for 4 h and above. APTT samples can be accepted up to 2 h only at RT or refrigerator.