Impact of Storage Time of Fresh Serum Samples on Rapid Test Results of HBsAg

• Published in: Viral Hepatit Dergisi Vol. 20; no. 2; pp. 61 - 63
• Main Authors: MENGELOGLU, Zafer, KOÇOGLU, Esra, BUCAK, Özlem, KARABÖRK, Seyda, TAS, Tekin
• Format: Journal Article
• Language: English; Turkish
• Published: Ankara Galenos Publishing House 01.08.2014
• Subjects: Antigens; Diagnostic tests; Hepatitis; Storage
• ISSN: 1307-9441; 2147-2939
• DOI: 10.4274/vhd.46220

Objective: Rapid tests, amongst the methods used in the diagnosis of hepatitis B virus infection, detect hepatitis B surface antigen (HBsAg). It is important to know whether the elapsed time between sample collection and the process has negative impact on the test results. It was aimed to evaluate the impact of samples stored either at room temperature (RT) or at +4 °C for different durations on rapid test results. Materials and Methods: A total of 51 serum samples were used. HBsAg tests were performed at the time the samples arrived at our laboratory using chemiluminescence method. 21 samples positive for HBsAg were accepted as the study group, and 30 negative samples were the controls. All the samples were tested immediately using rapid assay. Then the samples were divided into two aliquots and divided again into two groups; the first group was stored at RT, and the second was stored at +4 °C. Two or three hours after the first tests, all the samples were tested again using rapid assay, and then, they were continued to be stored; and after 24 hours, the tests were repeated for the third time. Test results were scored between "negative" and "+++". Results: In the initial rapid tests, the sensitivity rate was 85.7%, and the specificity was 100%. A statistically significant association was found between the positivity grades and the mean HBsAg levels (p<0.001; r=0.831). The accuracy was found to be 96.1% (49/51) for the second hour tests in terms of positivity grades. It was observed that the accuracy rate was decreased to 84.3% (43/51) in samples stored for 24 hours in both conditions, and positivity grades of eight samples were decreased for one degree for each. Amongst all tests, no false negative and false positive results were obtained according to the initial tests. In addition, it was found that all the results of the samples stored either at RT or +4 °C overlapped, and that the difference was caused just by the duration of storage. Conclusion: In conclusion, sera should not be stored for long time in cases they will be tested using HBsAg rapid assays, and storage of the samples for one day decrease the reliability of the results.