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It takes acid, rather than ice, to freeze glucose.

van den Berg SA, Thelen MH, Salden LP, van Thiel SW, Boonen KJ - Sci Rep (2015)

Bottom Line: We describe the effect of a variety of commonly used blood collection tubes on in vitro stability of glucose.Sodium fluoride alone does not reduce in vitro glycolysis in the first 120 minutes after phlebotomy.NaF-EDTA-citrate based test tubes provide the best pre-analytical condition available.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Clinical Chemistry and Hematology, Amphia Hospital, Breda, The Netherlands.

ABSTRACT
Plasma glucose levels provide the cornerstone of diabetes evaluation. Unfortunately, glucose levels drop in vitro due to glycolysis. Guidelines provide suitable conditions which minimize glycolysis, such as immediate centrifugation or the use of ice/water slurry storage containers. For obvious practical reasons, most laboratories use blood collection tubes containing glycolysis inhibitors. We describe the effect of a variety of commonly used blood collection tubes on in vitro stability of glucose. Furthermore, we looked at the validity of the assumption that glycolytic activity is minimal when blood is kept in an ice/water slurry. Sodium fluoride alone does not reduce in vitro glycolysis in the first 120 minutes after phlebotomy. Addition of citrate almost completely prevented in vitro glycolysis, but showed a positive bias (0.2 mmol/l) compared to control. This is partly due to a small drop in glucose level in control blood, drawn according to the current guidelines. This drop occurs within 15 minutes, in which glycolysis has been described to be minimal and acceptable. NaF-EDTA-citrate based test tubes provide the best pre-analytical condition available. Furthermore, glucose levels are not stable in heparinized blood placed in an ice/water slurry. We strongly advise the use of NaF-EDTA-citrate based test tubes in diabetes research.

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Related in: MedlinePlus

Time and tube type dependent free hemoglobin concentration and icteric index.Free hemoglobin concentration and icteric index at 0, 30, 60 and 120 minute time points, depicted per tube type, time points from left to right. Bars represent the different time points, from left to right: 0, 30, 60, 120 minutes. Bars represent mean plus SD, *p < 0.05 and **p < 0.01 for tube type/time interaction by two-way ANOVA, when compared to lithium-heparin tubes.
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f3: Time and tube type dependent free hemoglobin concentration and icteric index.Free hemoglobin concentration and icteric index at 0, 30, 60 and 120 minute time points, depicted per tube type, time points from left to right. Bars represent the different time points, from left to right: 0, 30, 60, 120 minutes. Bars represent mean plus SD, *p < 0.05 and **p < 0.01 for tube type/time interaction by two-way ANOVA, when compared to lithium-heparin tubes.

Mentions: A commonly encountered problem with phlebotomy material with a granulated rather than sprayed on additive is an increased number of hemolytic samples. We studied free hemoglobin concentration in all test tubes. In the control tubes, free hemoglobin content was similar between groups and did not exceed 15 μmol/l. Similar results were found for the icteric and lipemic indices, which were similar in control tubes of all test groups (data not shown). In NaF-EDTA test tubes, hemolytic index was similar to control tubes. In NaF-oxalate, the average hemolytic indices were significantly higher when compared to control tubes and increased with time (p < 0.01, Figure 3a). In NaF-EDTA-citrate tubes the average hemolytic indices were comparable to control at time point 0, but were also significantly higher when compared to control tubes and increased with time at all other time points (p < 0.05, Figure 3a). The 95th percentile of free hemoglobin concentration was; lithium-heparin 11, NaF-EDTA 12, NaF-oxalate 54 and NaF-EDTA-citrate 60 μmol/l, when determined over all test tubes, respectively. Lipemic indices did not differ between tube types, at any of the time points (data not shown). The icteric index was stable over time within a single test group, was lower in all NaF containing tubes, but was only significantly lower in NaF-EDTA-citrate containing material (p < 0.01, Figure 3b). These data show that hemolytic index is higher and increases in time in NaF-oxalate and NaF-EDTA-citrate test tubes. Lipemic and icteric indices were stable in time in NaF based tubes, and either lower or comparable to indices found in lithium-heparin test tubes.


It takes acid, rather than ice, to freeze glucose.

van den Berg SA, Thelen MH, Salden LP, van Thiel SW, Boonen KJ - Sci Rep (2015)

Time and tube type dependent free hemoglobin concentration and icteric index.Free hemoglobin concentration and icteric index at 0, 30, 60 and 120 minute time points, depicted per tube type, time points from left to right. Bars represent the different time points, from left to right: 0, 30, 60, 120 minutes. Bars represent mean plus SD, *p < 0.05 and **p < 0.01 for tube type/time interaction by two-way ANOVA, when compared to lithium-heparin tubes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352852&req=5

f3: Time and tube type dependent free hemoglobin concentration and icteric index.Free hemoglobin concentration and icteric index at 0, 30, 60 and 120 minute time points, depicted per tube type, time points from left to right. Bars represent the different time points, from left to right: 0, 30, 60, 120 minutes. Bars represent mean plus SD, *p < 0.05 and **p < 0.01 for tube type/time interaction by two-way ANOVA, when compared to lithium-heparin tubes.
Mentions: A commonly encountered problem with phlebotomy material with a granulated rather than sprayed on additive is an increased number of hemolytic samples. We studied free hemoglobin concentration in all test tubes. In the control tubes, free hemoglobin content was similar between groups and did not exceed 15 μmol/l. Similar results were found for the icteric and lipemic indices, which were similar in control tubes of all test groups (data not shown). In NaF-EDTA test tubes, hemolytic index was similar to control tubes. In NaF-oxalate, the average hemolytic indices were significantly higher when compared to control tubes and increased with time (p < 0.01, Figure 3a). In NaF-EDTA-citrate tubes the average hemolytic indices were comparable to control at time point 0, but were also significantly higher when compared to control tubes and increased with time at all other time points (p < 0.05, Figure 3a). The 95th percentile of free hemoglobin concentration was; lithium-heparin 11, NaF-EDTA 12, NaF-oxalate 54 and NaF-EDTA-citrate 60 μmol/l, when determined over all test tubes, respectively. Lipemic indices did not differ between tube types, at any of the time points (data not shown). The icteric index was stable over time within a single test group, was lower in all NaF containing tubes, but was only significantly lower in NaF-EDTA-citrate containing material (p < 0.01, Figure 3b). These data show that hemolytic index is higher and increases in time in NaF-oxalate and NaF-EDTA-citrate test tubes. Lipemic and icteric indices were stable in time in NaF based tubes, and either lower or comparable to indices found in lithium-heparin test tubes.

Bottom Line: We describe the effect of a variety of commonly used blood collection tubes on in vitro stability of glucose.Sodium fluoride alone does not reduce in vitro glycolysis in the first 120 minutes after phlebotomy.NaF-EDTA-citrate based test tubes provide the best pre-analytical condition available.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Clinical Chemistry and Hematology, Amphia Hospital, Breda, The Netherlands.

ABSTRACT
Plasma glucose levels provide the cornerstone of diabetes evaluation. Unfortunately, glucose levels drop in vitro due to glycolysis. Guidelines provide suitable conditions which minimize glycolysis, such as immediate centrifugation or the use of ice/water slurry storage containers. For obvious practical reasons, most laboratories use blood collection tubes containing glycolysis inhibitors. We describe the effect of a variety of commonly used blood collection tubes on in vitro stability of glucose. Furthermore, we looked at the validity of the assumption that glycolytic activity is minimal when blood is kept in an ice/water slurry. Sodium fluoride alone does not reduce in vitro glycolysis in the first 120 minutes after phlebotomy. Addition of citrate almost completely prevented in vitro glycolysis, but showed a positive bias (0.2 mmol/l) compared to control. This is partly due to a small drop in glucose level in control blood, drawn according to the current guidelines. This drop occurs within 15 minutes, in which glycolysis has been described to be minimal and acceptable. NaF-EDTA-citrate based test tubes provide the best pre-analytical condition available. Furthermore, glucose levels are not stable in heparinized blood placed in an ice/water slurry. We strongly advise the use of NaF-EDTA-citrate based test tubes in diabetes research.

Show MeSH
Related in: MedlinePlus