Abstract
Aims: The sample retention policy for Clinical Chemistry analytes in accredited medical laboratories as per ISO 15189:2012 is 24 hrs. Serum/ plasma to be separated in aliquot within 20 minutes of collection unless the primary containers are gel vacutainers. Rigorous maintenance of such procedure is difficult and as a result the possibility of deviation from such schedule may not be very uncommon. The 1 year Turn Around Time (TAT) analysis of the laboratory is a good guide to find out time lag from sample collection to sample processing & average time of collecting samples in aliquot for retained sample testing. The laboratory retested 22 common analytes on the basis of such time lag and evaluated the deviation from 1 st observation. The accumulated data has helped to evaluate and implement sample retention policy. Study Design: The average time lag from collection to completion of test performance of a batch is 4hrs± 30 minutes. The analytes were retested in the time lag. After accumulation of sufficient data the time lag increased to 6 hours±30 minutes which is the average lag from sample collection to end of the day duty personnel. In the 3 rd phase total retention time ie, 24 hrs has been considered as time interval of retained sample retesting. But the samples remained at room temperature for 6hrs±30minutes before being preserved at 2°C-8°C. Hence time lag was (6hrs±30min) at room temperature and 17hrs ±30min at 2°C-8°C. The samples always retested from primary container. Place and Duration of Study: The study took place in JMD Diagnostics Private Limited, Kolkata, Original Research Article Pal; BJMMR, 6(3): 265-277, 2015; Article no.BJMMR.2015.202 266 India. The duration of study is 2 yrs. Methodology: The analytes were tested in Cobas Integra 400plus system. The tests have been performed as routine tests and considered as 1 observation. 2 observation values obtained after the specified time lag. The results obtained were compared using statistical software. Comparison of 1 and 2 results and bias of all analytes were studied. Electrolytes have been eliminated from the study as the electrolytes are preferred to be retested from freshly collected sample. Labile parameters like L-Lactate, ammonia, bicarbonate were also not considered for the same reason. Conclusion: Only 3 analytes, total protein, total calcium and inorganic phosphorus cannot be preserved in primary containers. The analytes also need not to be separated within 20 minutes of collection. Upto 4hrs±30 minutes all the parameters have shown excellent correlation coefficient. Hence, the laboratory earns a time lag between collection to preservation of samples for these analytes. For other 19 analytes sample may be kept in primary container.
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