BIOELECTRICAL-IMPEDANCE ANALYSIS TO IMPROVE ESTIMATES OF CREATININE CLEARANCE IN RENAL TRANSPLANT RECIPIENTS

The creatinine clearance is commonly accepted as the best parameter to asses
the kidney function. There are many different mathematical formulas to make an
estimation of the creatinine clearance. Most of them are based on the
measurement the serum creatinine concentration. The evaluation and availability
of various formulas taken with the fact that none of these formulas is adequate
for all patient populations can lead to confusion and misunderstanding in daily
practice when estimating kidney function.
In renal transplant recipients formulas that predict creatinine clearance (such
as the Cockcroft-Gault) derived from patients with chronic renal failure and
standardized against measured creatinine clearance are not accurate.
In these patients the relationship between serum creatinine and creatinine
clearance is more variable and dependent on factors (e.g. disease states) that
alter muscle mass and muscle catabolic rate.
Preceding research has shown that variables as age, sex, ethnicity, height and
weight explain a significant part of the variability of the kidney function.
It*s has been commonly accepted that these variables have a direct influence on
kidney function and are used combined with serum creatinine to estimate the
creatinine clearance. However these variables are also predictors of skeletal
muscle mass, the biggest source of creatinine, the clearance of which is used
to estimate the creatinine clearance .
Skeletal muscle mass can be predicted by the use of demographic variables but a
more accurate estimation method uses bioelectrical impedance analysis (BIA).
BIA is an easy non-invasive and convenient method to assess a patient*s total
body composition, including muscle mass. By measuring the total body
composition an accurate estimation of the muscle mass can be made

This study is aimed at the development of a noninvasive method which leads to a
more accurate and precise estimation of the creatinine clearance when compared
with the Cockroft-Gault, MDRD or Nankivell formulas and taking the 24-hour
urine creatinine clearance as a reference in renal transplant recipients.
Using the formulas mentioned above (also see Methods) combined with bio
impedance measurements, we hypothesize that bio impedance will prove to have
additional value as a predictor of the muscle mass of a patient. This may lead
to a better prediction of the creatinine clearance than with currently used
methods.

Observational study

participants will have 4 electrodes (2 to hand, 2 to foot) placed for every BIA
measurement, after which a read-out takes place. The burden and risks can be
considered to be very small.