Testa A, Beaud JM, Soulillou JP
Is interdialytic weight gain a nutritional parameter?
Am Soc Nephrol
J Am Soc Nephrol (abstract)
(Sep) 7:1527 1996
"Non-compliance" has traditionally been measured in part by assessment of
IDWG. Recently, "non-compliant" patients have been shown to have better
mortality rates. Higher BUN's, and higher creatinines are associated with
longer survival, presumably because these values are surrogates for higher
protein catabolic rates (PCR), which the National Cooperative Dialysis
Study showed long ago was an important determinant of mortality. IDWG is
often thought of as a marker of fluid intake, but since food, like people,
is mostly water, food intake correlates with IDWG too and may be the
predominant source of IDWG. Higher IDWGs could be associated with improved
mortality if protein intake is higher. This benefit would not be expected
if the source of the IDWG is higher fluid intake. Similarly, IDWG
attributed to sodium intake, with ensuing thirst and fluid intake, in the
form of low-protein foods, would not be expected to confer improved
mortality.
The authors divided 38 hemodialysis patients with 128 sessions, into 2
groups: group A gained less than 5% of dry body weight between treatments,
and group B gained more than 5%. In-line urea monitoring (with Baxter UM
1000) was used to measure urea kinetics. Group B had significantly higher
urea removal, Kt/V, pre-dialytic BUN, solute removal index. IDWG was an
independent variable that significantly correlated with nPCR. Surprisingly
pre-treatment BP did not differ between the 2 groups.
Comment: IDWG is therefore a "nutritional parameter" that
correlates positively with PCR. In retrospect this should have been
intuitively obvious. As dialysis adequacy improves, appetite improves and
PCR rises. IDWG follows. However, before we further remove dietary
restrictions (not potassium yet!) we need to consider that perhaps among
patients with higher PCRs those with lower IDWG are better off still. No
morbidity, mortality or hospitalization data are given here. And no IDWG
that's clearly excessive is delineated: one would expect a clinical
difference between 6% and 10%, for instance. Before accepting higher IDWGs
we need to know that more edema, higher BPs, higher ultrafiltration rates
with more hypotension and cramps, and more hospitalizations with
unscheduled treatments do not result. And we need to ensure adequated PCRs
in dialysis patients. (David S. Goldfarb, M.D., NYU School of
Medicine)
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Am Soc Nephrol
CRF by organ system :
Nutrition
Basic hemodialysis :
Complications (acute)