Liju,
Not only for trace elements but also for all other biomarkers expressed
as ratios with creatinine, age and sex adjusted reference intervals
should be given, where appropriate; it is well known that children and
older adults have difference creatinine levels than younger adults, as
well as some females relative to their male counterparts; the problem is
that labs in general have been slow in adapting age-stratified reference
intervals for creatinine ratio measurements because of the differences
in creatinine methodologies/assays. This is changing rapidly with
standardization and hopefully more labs will be determining or
establishing RI's for these ratios; I do support your move to do so for
your lab, especially as it relates to environmental/occupational
testing.
Regards,
Godfrey
-----Original Message-----
From: Clinical biochemistry discussion list
[mailto:[log in to unmask]] On Behalf Of Liju Yang
Sent: Friday, June 25, 2010 11:45 AM
To: [log in to unmask]
Subject: Age- and sex-adjusted urinary creatinine
Dear List Members,
For trace element (and some other analyte) testing on a random urine
sample, urinary creatinine concentrations have been commonly used to
adjust the effect of urinary dilution on element concentrations and the
result is reported as a ratio of analyte/creatinine (umol/mol
creatinine). However, children and elderly people have lower urinary
creatinine concentrations compared with adults, thus creatinine
adjustment increases their urinary analyte concentrations. See attached
articles.
We are considering introducing the age- and sex-adjusted urinary
creatinine concentration to improve the accuracy of the result. Just
wonder if other lab/centres out there have already done this. What's
your opinion about this approach? Are there any guidelines available?
Thank you.
Liju Yang, PhD, FCACB
Clinical Chemist
Clinical Immunology/Trace Elements Laboratory
University Hospital
London Health Sciences Centre
London, ON N6A 5A5
Tel. (519) 685 8500 ext. 35768
Fax. (519) 663 3980
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