Serum Gel Tubes Research Articles

Stability of common biochemical analytes in serum gel tubes subjected to various storage temperatures and times pre-centrifugation

Blood samples collected in rural and remote areas of Australasia are often exposed to a range of environmental conditions prior to analysis in a laboratory. The aim of this study was to determine analyte stability of venous blood specimens in serum gel tubes exposed to a range of storage temperatures and times prior to centrifugation. Thirty healthy adult volunteers were enrolled in the study. Blood was collected into 11 serum gel separator tubes. All samples were allowed to clot at room temperature for 30 min. Two samples were centrifuged and analysed as controls. Nine samples were stored at 15, 25 or 35 degrees C for 4, 8 or 24 h, respectively, before centrifugation. Thirty-five biochemical analytes were measured on each sample. Most analytes remained stable in all storage conditions including sodium, total protein, albumin, bilirubin, alanine transferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase, creatinine kinase, lipase, cholesterol, triglycerides, transferrin, urate, C-reactive protein, vitamin B(12), thyroid-stimulating hormone, free thyroxine, free triiodothyronine, follicle-stimulating hormone, oestradiol, prostate-specific antigen, cortisol and vitamin D. Potassium, glucose, phosphate, creatinine, urea, ferritin, iron, lactate dehydrogenase, magnesium and calcium were not stable in at least one of the storage conditions. These results can be used to determine which analytes produce valid results despite exposure to variable storage conditions for up to 24 h prior to centrifugation. The majority of analytes were unaffected by a delay in centrifugation at a variety of temperatures, however, some important analytes were significantly affected.

A case of hyperkalaemia associated with hypocalcaemia

An 84-year-old woman presented with lethargy and anorexia. Although routine biochemistry demonstrated mild hyponatraemia, moderate hyperkalaemia and severe hypocalcaemia, the patient did not demonstrate the usual symptoms of hypocalcaemia. An...

Glycolysis inhibitors negatively bias blood glucose measurements: potential impact on the reported prevalence of diabetes mellitus

Background: Blood glucose concentrations are essential in defining diabetes mellitus. Recent guidelines advocate either of two discrete methods for sample collection and processing. One of these involves addition of glycolysis...

Evaluation of three different specimen types (serum, plasma lithium heparin and serum gel separator) for analysis of certain analytes: clinical significance of differences in results and efficiency in use

There is a lack of consensus regarding the most appropriate specimen type for analysis of many biochemistry analytes. The aim of this study was to compare renal and lipid analyte profiles and phenytoin values in plain serum (S), serum gel (G) and plasma (lithium heparin, P) tubes and to investigate the stability of these analytes after prolonged contact with cells or gel at room temperature (RT, 20 degrees C) and as aliquoted and stored at 4 degrees C. Primary specimens were centrifuged once, maintained at RT and analysed within 2 h (T(0)) and after 24 h (T(24)) and 48 h (T(48)). For assessment of stability at 4 degrees C, two cell-free aliquots were separated from each of the primary tubes and stored at 4 degrees C and then analysed at T(24) and T(48). Differences in analyte concentrations between tubes at T(0) and following storage (at T(24) and T(48)) were evaluated for both statistical and clinical significance. At T(0) all analytes, except potassium, demonstrated equivalence between serum, gel and plasma tubes. Potassium and creatinine were more stable in gel tubes than in serum/plasma tubes. In contrast, phentytoin was stable in plain serum and plasma up to T(48) at RT, but showed a progressive and clinically significant decrease in concentration in gel tubes at T(24) and T(48) at RT. All analytes except CO(2) were stable up to T(48) when aliquoted and stored at 4 degrees C. We concluded that the serum gel tube has advantages over plain serum and plasma tubes for measurement of the analytes investigated in this study, with the exception of phenytoin. In practice, the gel tubes demonstrate enhanced analyte stability and reduce the need to aliquot specimens, with greater protection against possible contamination. Further investigation would be required to evaluate a broader range of analytes.

Toluene, 1-butanol, ethylbenzene and xylene from Sarstedt Monovette serum gel blood collection tubes.

Gross contamination with ethylbenzene and xylene from Sarstedt Monovette (Sarstedt UK, Leicester, UK) serum gel blood tubes has been reported previously.' The contamination observed would have indicated acute poisoning if the source of the solvents had not been recognized, and was several orders of magnitude higher than contamination with organic solvents reported from Vacutainers (Becton Dickinson UK, Oxford, UK).2 The process used in' the manufacture of Sarstedt Monovette serum gel tubes has now changed. We have found that serious contamination with toluene can arise from all batches of such tubes available in the UK from January 1994.