Mendley SR, Majkowski NL
Dietary intake does not improve with increased Kt/V in
chronic pediatric PD patients
Am Soc Nephrol
J Am Soc Nephrol (abstract)
(Sep) 7:1522 1996
There has been an ongoing controversy for many years as to whether
prospective increases in
peritoneal clearance increase dietary protein intake. The correlation seen
between clearance and
intake in cross-sectional studies has been confounded by arguments about
mathematical coupling A few
small prospective studies in adults have been done with most, but not all,
showing some increase in
protein catabolic rate when clearance is raised. In this study, Mendley et
al look at five children
and use a crossover technique with each child receiving usual PD with a
weekly KT/V of 1.7 and
intensive PD with a weekly KT/V of 2.1, for four months each in random order.
At the end of each
four month period at least four measurements are made of dietary protein and
caloric intake using 3
day diet logs as well as measurement of nitrogen output by the Kjeldahl
method for assessment of
protein intake. Normalization was to ideal rather than actual body weight.
The investigators found that mean dietary protein intake for the entire study
was 1.6 grams/kg/day
and caloric intake was 44 kcal/kg/day. Both were unaffected by alterations
in KT/V.
Comment: This is a fascinating study. It is probably methodologically
the best to look at
this issue to date, in either adults or children. It's findings that protein
and caloric intake are
independent of clearance are similar to those of Harty et al in adult
patients but in conflict with
those of other investigators. However, most studies in this area are not
methodologically ideal.
One possibility to explain the findings is that the correlation between
clearance and protein intake
may only exist at KT/V values < 1.7/week. There has been some evidence in
the adult population
of a flattening of the curve relating clearance to protein intake as KT/V
gets higher. The "break
point" may be as low as 1.7 in adults as well as children. It is also
notable that the level of
protein and calorie intake is much higher in these patients than in adults.
This may simply reflect
the fact that children eat more per body weight than adults, but it might
also reflect lesser
degrees of comorbidity in a
pediatric population. This sort of study needs to be done in an adult
population. (Peter G. Blake, M.D., Victoria Hospital, London,
Ontario)
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Am Soc Nephrol
CRF by problem area :
CRF in infants and children
Basic peritoneal dialysis :
Chronic PD regimens, adequacy, modeling