PharmPK Discussion - Creatinine Clearance & IBW in Patients that are "Small"

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On 25 Feb 1997 at 12:35:54, Marc.A.Semprebon.-at-.Hitchcock.ORG (Marc A. Semprebon) sent the message


     I am always running into non-pediatric patients, usually elderly, but
could be any age group, who do not fit (naturally!) the standard 5 feet tall +
scenario OR have ABW that are <45.5 kg or 50 kg for male or female,
respectively.  Someone recently (and of course I can't find the formula!) had a
CrCl calculation encorporating serum albumin for patients with low values, but
this is NOT the patient population I am looking for (though some may fit into
this category).  Any suggestions?

Marc Semprebon, RPh
DHMC
Lebanon, NH  03756

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On 26 Feb 1997 at 16:20:32, Nick Holford (n.holford.at.auckland.ac.nz) sent the message


>
>      I am always running into non-pediatric patients, usually elderly, but
> could be any age group, who do not fit (naturally!) the standard 5 feet
>tall +
> scenario OR have ABW that are <45.5 kg or 50 kg for male or female,
> respectively.  Someone recently (and of course I can't find the formula!)
>had a
> CrCl calculation encorporating serum albumin for patients with low
>values, but
> this is NOT the patient population I am looking for (though some may fit into
> this category).  Any suggestions?

At least part of the problem you appear to be having may be helped by
using a suitable model for size. This may help particularly with smaller
than average people e.g.

CL =CLstd x (Wt/Wtstd)^3/4

where CLstd is the CL in a 'standard' size person with weight Wtstd. You
can use total body weight, ideal body weight.

See this for details:
Holford NHG. A size standard for pharmacokinetics. Clin Pharmacokin
1996;30:329-332

PS Does ABW mean average body weight?

--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, Private Bag 92019, Auckland, New Zealand
email:n.holford.-a-.auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556
http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.html

[db ABW == actual body weight ?]

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On 27 Feb 1997 at 10:34:24, djtippey.-at-.dbtech.net (Del & Jackie Tippey) sent the message


Thanks for the info. I'm going to check it out.
>
>PS Does ABW mean average body weight?
>
It's an acronym for actual body weight.
>
-DT-
Del Tippey R.Ph., M.S.S.M.
DCH Regional Medical Center
801 University Blvd. E.
Tuscaloosa,AL 35405
1-205-759-7310
djtippey.aaa.dbtech.net

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