Reza Morovat wrote:
> There have been a few articles that have suggested no effect on
> serum creatinine by creatine supplements (see e.g. Clin. Chem.
> 2000; 46: 295-7).
Changes in creatinine have been found after creatine
supplementation.
JM Schedel, H Tanaka, A Kiyonaga, M Shindo, and Y Schutz
Acute creatine ingestion in human: consequences on serum creatine
and
creatinine concentrations.
Life Sci, October 29, 1999; 65(23): 2463-70.
They found an 18% increase in serum creatinine after a single 20g
creatine dose. This is four times the usual daily maintainance dose.
This only involves the conversion of a small percentage of the
creatine to creatinine.
> I have one question which is separate to all this but still on
> the subject of creatinine and creatine: A low pH, such as that
> which you find in urine, can convert creatine to creatinine
> (increasing urinary creatinine in vitro by up to 20% in 24 hours
> in one report - though I guess that's probably an extreme case).
> Should we worry about this when measuring creatinine clearance
> using 24-h urines that have been sitting around for a while?!
When looking at stability of urine spiked with creatine I found that
50% of the creatine was lost overnight. None of the suggested
preservatives I found in the literature had any effect. Refrigerating
the sample only reduced the loss slightly. Only freezing seemed to
work.
The clinical trial I was doing this work for was abandoned so I have
not completed the work.
So I think it likely that creatine supplementation would affect urinary
creatinine.
Mike Collins
Mike Collins MLSO3
Clinical Biochemistry & Immunology
The General Infirmary at Leeds,
Old Medical School, Thoresby Place,Leeds LS1 3EX, UK
[log in to unmask] [log in to unmask]
44 (0) 113 392 2915
http://www.leedsteachinghospitals.com
.
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