-(ED 3287)
Uniformisation of units in clinical chemistry in Belgium
Editorial
Uniformisation of units of
measurement in clinical chemistry
in Belgium starting December 2012
Cammaert P1, Martens F2, Van de Walle P3, Braekevelt B4, Verstraete AG5
1
Labo Van Poucke, Kortrijk, 2Laboratory AZ Groeninge, Kortrijk, 3Institute of Public Health,
department Quality of Medical Laboratories, 4Laboratory OLV van Lourdes, Waregem,
5
Laboratory of Clinical Biology, Ghent University Hospital and Department of Clinical Chemistry,
Microbiology and immunology, Ghent University, Belgium
Correspondence and offprint requests to: Alain Verstraete E-mail: [email protected]
Key words: clinical chemistry, laboratory medicine, uniformisation
In Belgium various units are in use for several parameters
in clinical chemistry (example of calcium in Table 1). The
actual situation has historical roots. Results of analyses performed on the blood of patients in different laboratories
using different units can cause interpretation errors. Using
different units in this era of continuous exchange of laboratory data amongst practitioners and hospitals is no longer
justified. It is important to have a uniform application of units
on a local or national scale in order to avoid confusion
amongst practitioners and patients. The Belgian government
encourages laboratory data exchange by promoting the
e-Health platform. One of the conclusions of the Perl Task
Force concerning this initiative was: “The applications of
eHealth to avoid the unnecessary repetition of examinations.”
This is a first, necessary step towards the ultimate goal of harmonisation of results and reference values.
In the world many countries like the UK, the Netherlands
and Scandinavian countries use the SI (système international)
units, while Belgium, the US and others use traditional units.
Table 1: units in use for calcium in Belgian laboratories
(based on the results from the national external
quality evaluation)
Units
% of Belgian
laboratories that
use them
Reference values
Factor to
mmol/L
mg/L
 7%
88 – 104
× 0.025
mg/dL
58%
8.8 – 10.4
× 0.25
mEq/L
18%
4.40 – 5.20
× 0.5
mmol/L
17%
2.20 – 2.60
×1
doi: 10.2143/ACB.67.0.2062000
In the scientific journals, there is no consensus either. This
journal’s instructions to authors mentions that authors of articles must express all measurements in SI units and that the
authors may include conventional units in parentheses if they
desire. According to the European Association of Science Editors Guidelines for Authors and Translators of Scientific Articles
to Be Published in English, the SI units are generally preferred.
Early on, many journals switched to SI units, but they backtracked somewhat, and this is still reflected in the International
Committee of Medical Journal Editors Uniform Requirements
for Manuscripts Submitted to Biomedical Journals: Writing and
Editing for Biomedical Publication, which state that “Journals
vary in the units they use for reporting hematologic, clinical
chemistry, and other measurements. Authors must consult the
Information for Authors of the particular journal and should
report laboratory information in both local and SI Units. Editors
may request that authors add alternative or non-SI units, since
SI units are not universally used. Drug concentrations may be
reported in either SI or mass units, but the alternative should be
provided in parentheses where appropriate.” (1)
The New England Journal of Medicine tried to impose the
use of SI units in all publications in 1987, but it had to reverse
course in 1992 (2). Nowadays, in e.g. the New England Journal of
Medicine and Clinical Chemistry, the guidelines for publication
ask to mention SI units between brackets when traditional units
are used but in accordance with the Uniform Requirements, however, manuscripts containing only SI units will not be returned for
that reason (3, 4). In Clinical Chemistry electrolytes are expressed
in SI units and hsCRP in mg/L (4). In the journals of the Endocrine
Society, results should be expressed in metric units and SI units
must be added in parentheses. In particular cases i.e. growth hormone, there is an international consensus (5).
In Belgium all attempts for an overall introduction of the
SI units in the past have failed and such a huge changeover
is not feasible.
Acta Clinica Belgica, 2012; 67-?
1
2
Uniformisation of units in clinical chemistry in Belgium
Under the auspices of the Commission of Clinical Biology
at the Scientific Institute of Public Health, the working group
Clinical Chemistry has made a list of “preferable units”.
The most important starting points are:
– on the basis of a general consensus 16 parameters (Table 2)
keep their traditional units e.g. mg/dL for creatinine, urea,
uric acid, …
–In the case where several units are in use for the same
parameters expression in SI units is encouraged. For about
35 parameters the numerical value remains the same. Only
the unit changes e.g. Sodium expressed in mEq/L becomes
mmol/L. This is already implemented in the great majority
of labs.
For 9 parameters (Table 3) the numerical value changes
while converting to another unit. This national uniformisation
is planned for the first week of December 2012.
Depending on the kind of units actually in use by a given
laboratory 0 to 9 units and values have to be changed. Special
Table 2: Parameters that keep the old units
Analyte
Units
Total bilirubin
mg/dL
Direct bilirubin
mg/dL
Creatinine
mg/dL
Glucose
mg/dL
Uric acid
mg/dL
Iron
µg/dL
Cholesterol
mg/dL
HDL-cholesterol
mg/dL
Triglycerides
mg/dL
Urea
mg/dL
AST (aspartate aminotransferase)
U/L
ALT (alanine aminotransferase)
U/L
GGT (gamma-glutamyltrasferase)
U/L
LDH (lactate dehydrogenase)
U/L
Alkaline phosphatase
U/L
Amylase
U/L
Table 3:New uniform units from December 2012
Parameter
Unit
Calcium
mmol/L
Phosphorus
mmol/L
Magnesium
mmol/L
CRP (C-reactive protein)
mg/L
Total protein
g/L
Albumin
g/L
IgA
g/L
IgM
g/L
IgG
g/L
Acta Clinica Belgica, 2012; 67-?
attention is needed for CRP and calcium. Due to a conversion
from mg/dL to mg/L the numerical value of CRP will rise with
a factor 10 in about 50% of the labs in Belgium. For calcium,
physicians, pharmacists, nurses, lab technicians and patients
will have to deal with other reference and critical values.
This important switch in units has been prepared since a
few years and Extensive information on this subject is available on the website of the department Quality of Medical
Laboratories (6). This website contains a road map for laboratories, a risk analysis and conversion tables.
This is only a first step. The final goal is that laboratory
results and reference values should be harmonised in the
whole country or even in the European Union. In the Netherlands, initiatives for harmonising reference values in haematology were already taken 15 years ago (7). For several
regions in the Netherlands, uniform reference values have
been set (8). In the UK, Pathology Harmony is an initiative
working towards harmonisation in UK pathology laboratories which was established in January 2007 (9). By 31st March
2013 units for reporting full blood count should be standardised including the Haemoglobin level and MCHC as g/L in
the UK. In 2010, the American Association for Clinical Chemistry has launched the Global Harmonization Initiative that
will bring together a variety of stakeholders in the lab community to systematically select and prioritise harmonisation
projects (10).
The authors realise that this switch in units will not be
easy for the clinicians but they hope that with the careful
preparations and good communication between the laboratory and the requesting physicians, this first step towards
harmonisation of the units and reference values in Belgium
can be taken.
References
1. International Committee of Medical Journal Editors. Uniform Requirements for
Manuscripts Submitted to Biomedical Journals: Writing and Editing for Biomedical Publication. http://www.icmje.org/urm_full.pdf (Accessed September
1 2012).
2. Campion EW. A retreat from SI units. N Engl J Med 1992; 327: 49.
3. Author Center, New Manuscripts. http://www.nejm.org/page/author-center/
manuscript-submission (Accessed Aug 30, 2012).
4. Clinical Chemistry Policy on Reporting of Concentration Units. Clin Chem 2011;
57: 788.
5. Trainer PJ, Barth J, Sturgeon C, Wieringa G. Consensus statement on the standardisation of GH assays. Eur J Endocrinol 2006; 155: 1-2.
6. Uniformisering eenheden. https://www.wiv-isp.be/ClinBiol/bckb33/uniformisation-des-unites/_n/uniformisering.htm (Accessed September 1 2012).
7. Pronk-Admiraal CJ, Van Alphen-Jager JM, Herruer MH. Uniformity in hematological reference values to be used in a vast region. Ned Tijdschr Klin Chem 1997;
22: 192-194.
8. Regio-overzichten uniforme referentiewaarden. http://www.nvkc.nl/klinische_
chemie/referentiewaarden.php (Accessed July 20 2012).
9. Pathology Harmony. http://www.pathologyharmony.co.uk (Accessed July 20
2012).
10. Greg Miller W, Myers GL, Lou Gantzer M, Kahn SE, Schonbrunner ER, Thienpont
LM, et al. Roadmap for harmonization of clinical laboratory measurement procedures. Clin Chem 2011; 57: 1108-1117.