Storage of serum or whole blood samples? Effects of time and temperature on 22 serum analytes.

Institut für Klinische Chemie und Laboratoriumsdiagnostik der Heinrich-Heine-Universität Düsseldorf, Germany.
European journal of clinical chemistry and clinical biochemistry: journal of the Forum of European Clinical Chemistry Societies 04/1995; 33(4):231-8. DOI: 10.1515/cclm.1995.33.4.231
Source: PubMed

ABSTRACT Information on the stability of serum analytes during storage of serum or whole blood samples is often incomplete and sometimes contradictory. Using a widely available analyser (Hitachi 737/Boehringer), we therefore determined the effects of storage time and temperature on the measured concentrations of the following serum analytes: sodium, potassium, calcium, chloride, inorganic phosphate, magnesium, creatinine, urea, uric acid, bilirubin, cholesterol, HDL- and LDL-cholesterol, triacylglycerols, creatine kinase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, alpha-amylase, lactate dehydrogenase and cholinesterase. When separated serum was stored at + 9 degrees C for seven days, the mean changes in inorganic phosphate and lactate dehydrogenase exceeded significantly (p < 0.05 or 0.001, respectively) the maximum allowable inaccuracy according to the Guidelines of the German Federal Medical Council; all other quantities were sufficiently stable. In serum at room temperature, inorganic phosphate, uric acid, HDL-cholesterol and triacylglycerols increased continuously, whereas bilirubin, LDL-cholesterol, creatine kinase and aspartate aminotransferase decreased more than the guidelines permit during the storage period (p < 0.05 for aspartate aminotransferase, p < 0.001 for the other analytes mentioned). In whole blood stored for 7 days at + 9 degrees C, only the following serum analytes satisfied the stability requirements of the guidelines: calcium, urea, cholesterol, HDL-cholesterol, LDL-cholesterol, triacylglycerols, creatine kinase, gamma-glutamyltransferase and cholinesterase. When stored at room temperature, only sodium, uric acid, bilirubin, cholesterol, triacylglycerols, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, alpha-amylase and cholinesterase were still stable after 3 days. The data collected show that all quantities examined are sufficiently stable for four days in separated serum stored at + 9 degrees C.

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    ABSTRACT: To evaluate the stability of electrolytes in serum samples due to delay in analysis in a tertiary care government hospital in India, and the maximum time delay acceptable between sample centrifugation and analysis. We estimated serum electrolytes of 400 samples with different time intervals between centrifugation and sample analysis on automated analyser. Values were compared using repeated measure ANNOVA and acceptable limit change using in house QC values of 6 months. During the time interval between centrifugation and sample analysis, the samples were kept uncovered in sample cups in the laboratory. Potassium values show significant changes within 1 h (T1, p<0.01) but sodium (T2, p <0.01) and chloride (T2, p <0.001) values are acceptable up to a time delay of 3 h between sample centrifugation and analysis. Samples for electrolytes should be analysed within 1-2 h of centrifugation and if there is any delay in analysis, the samples should be stored under proper conditions.
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    ABSTRACT: Author's contribution The sole author designed, analyzed and interpreted and prepared the manuscript. 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. 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 st observation. 2 nd observation values obtained after the specified time lag. The results obtained were compared using statistical software. Comparison of 1 st and 2 nd 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.
  • Clinica Chimica Acta 09/2014; 439. DOI:10.1016/j.cca.2014.09.025 · 2.76 Impact Factor


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