Mike, referring to your comments below, as one of the evidence-based methodological contributors to the development of the referred NACB guideline, I can assure that the authors of this quoted chapter have all been highly reputed experts actively working in laboratories and they did their best to explore the evidence behind their statements. They also graded their recommendations in a very involved considered judgment process which took into account impact on patient relevant outcomes as well as practicality (see Table 3 in Appendix and Preamble for methodology). Furthermore the NACB guideline was peer reviewed and widely consulted 2x internationally before its release and you can find the names of numerous well known active professionals in Table 1 of the Appendix.
If you read the whole guideline and look at its evidence tables (see p 66-67 of the attached) and the quoted references, you will find that it actually says the followings and points out the (im)practicality of each option too:
"Few effective and practical methods are available for prompt stabilization of glucose in whole-blood samples. Loss of glucose can be minimized in 2 classic ways: (a) immediate separation of plasma from blood cells after blood collection (the glucose concentration is stable for 8 h at 25 °C and 72 h at 4 °C in separated, nonhemolyzed, sterile serum without fluoride( 61)); and (b) placing the blood tube in an ice-water slurry immediately after blood collection and separating the plasma from the cells within 30 min (19, 62). These methods are not always practical and are not widely used. A recent study showed that acidification of blood with citrate buffer inhibits in vitro glycolysis far more effectively than fluoride (62). The mean glucose concentration in samples stored at 37 °C decreased by only 0.3% at 2 h and 1.2% at 24 h when blood was drawn into tubes containing citrate buffer, sodium fluoride, and EDTA. The use of these blood-collection tubes, where they are available, appears to offer a practical solution to the glycolysis problem."
I believe it is important that people read the entire guideline before taking statements out of context.
Furthermore, guidelines are only for guidance and you can translate the evidence quoted to your local environment as much as possible and practicable. This is clearly pointed out in the Preamble of the guideline too as follows (see p. xi):
"Although recommendations have been developed for national and international use and are intended to be generic, certain elements of this guideline will not reflect views that are universally held, and other elements may have limited applicability in healthcare settings that lack sufficient resources for adopting the recommendations. The guideline committee advises users to adapt recommendations to their local settings. During such adaptation processes, the evidence tables provided (see Appendix Table 3) might assist users in making informed decisions."
However, guidelines are living documents and if any new and more practical evidence comes to light, the guideline team is more than happy to include those in future updates.
Regards, Rita
Prof. Andrea Rita Horvath
Clinical Director
SEALS North, Department of Clinical Chemistry
Level 4, Campus Centre, Prince of Wales Hospital
Barker Street, Randwick, NSW 2031, Sydney, Australia
Tel: (+612)-9382 9078
Fax: (+612)-9382 9099
Mobile No: (+61)-404 027 843.
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Steiner, Michael
Sent: Thursday, 18 August 2011 1:02 AM
To: [log in to unmask]
Subject: Place samples in ice-water ...
Craig,
Do you know if any of the panel members who issued this recommendation has ever worked in a busy routine lab ?
If yes: good that they left the lab at time ...
If not: no wonder that ice-water is their recommendation ...
To cut a long story short: please, do not overregulate/overcomplicate things.
On more scientific grounds the question will be: Who has compared glycolytic inhibitor alone versus ice-water alone versus their combination and published the (may be) evidence in favour of the combination ?
Best regards,
Mike
-----Ursprüngliche Nachricht-----
Von: Clinical biochemistry discussion list [mailto:[log in to unmask]] Im Auftrag von Webster Craig
Gesendet: Mittwoch, 17. August 2011 15:29
An: [log in to unmask]
Betreff: GTT
is anyone else collecting GTT samples onto ice as per this WHO recommendation
"Glucose should be measured immediately after collection by near-patient testing, or if a blood sample is collected, plasma should be im- mediately separated, or the sample should be collected into a container with glycolytic inhibitors and placed in ice-water until separated prior to analysis. "
http://www.who.int/diabetes/publications/Definition%20and%20diagnosis%20of%20diabetes_new.pdf
Best Wishes
Craig
Craig Webster
Consultant Clinical Scientist
Birmingham Heartlands Hospital
Birmingham
B95SS
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