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Does anyone have knowledge/references;
When does the gender difference in CLcreatinine (Cockcroft Gault) renal
function seen in adults appear during the aging process?
Especially over the ranges of < 2yrs, 2-12 yrs, 12-18 yrs.
Thanks,
Dave
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The following message was posted to: PharmPK
Dave,
David Benziger wrote:
>
> Does anyone have knowledge/references;
>
> When does the gender difference in CLcreatinine (Cockcroft Gault)
renal
> function seen in adults appear during the aging process?
>
> Especially over the ranges of < 2yrs, 2-12 yrs, 12-18 yrs.
The sex factor in C&G accounts for differences in muscle mass per kg of
total body weight. My guess is that male and female ratio of muscle
mass to TBW develops at puberty.
Nick
--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New
Zealand
email:n.holford.at.auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556
http://www.health.auckland.ac.nz/pharmacology/staff/nholford/
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Hi Dave,
It would seem reasonable to assume that the gender difference in the
C-G equation (i.e. female CLcreat = 0.85 * the calculated male value)
occurs soon after puberty when male muscle mass per Kg body weight
would typically begin to exceed that of females (i.e. relatively higher
serum creatinine concentrations would then be expected in males at
least until "old age").
For infants less than one year CLcreat is calculated as 0.45 x length
(cm)/serum creatinine (mg/100 ml). In children, between 1 and 12 years
of age the equation is the same except that 0.55 (instead of 0.45)
appears in the numerator.
Regards,
Peter
Peter W. Mullen, PhD, FCSFS
KEMIC BIORESEARCH
Kentville
Nova Scotia, B4N 4H8
Canada
Tel.: 902-678-8195 Fax: 902-678-2839 Email: pmullen.at.kemic.com
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The following message was posted to: PharmPK
Hi Dave
from my (poor) memory, the Cockcroft & Gault paper was one gender
only and its intent was not necessarily to be used in the way that has
resulted over a number of years now. It does not measure CrCl in the
classical sense of UV/P (corrected for surface area) but tries to show
a correlation and ability to calculate it via other formulae. I don't
know of larger studies proving how good this is in normal, mixed
gender populations.
clinically, the paper demonstrates deteriorating function vs age in
the population studied. However, looking at large populations,
deteriorating clearance demonstrable as clinically significant relies
on a large amount of glomerular dysfunction due to the high redundancy
present physiologically by having two kidneys. So interpretation or
extrapolation to general deteriorating function vs age/gender seems
difficult.
There are many quoted reference ranges for CrCl in children & adults -
I cannot remember seeing a childs ref range broken down into gender,
nor into the age ranges you list - others may know of them:
one example would be:- (Jacobs et al 3rd ed)
children 70-140mL/min/1.73m^2
adults:male 85-125mL/min/1.73m^2
adults:female 75-115mL/min/1.73m^2
(Intra-individual variation is about 15%)
I have seen ref ranges for serum creatinine broken down further eg:-
M(1-6y) 35 - 71 umol/L
F(1-6Y) 35 - 71 umol/L
M(7-18y)53 - 123umol/L
F(7-18y)44 - 106umol/L
(Paediatric Reference Ranges,Soldin & Hicks, AACC Press,1995)
an interesting subject - in previous studies I have been involved in,
we conducted both C&G and classical CrCl via serum/24h urine & SA, and
the interpretation was very different. It does depend on the model and
study intent, but in general its fair to say that C&G makes me
nervous!
best wishes
John
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