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Whole-Body Protein Metabolism in Chronic Heart Failure: Relationship to Anabolic and Catabolic HormonesFrom the Department of Medicine, University of Vermont, Burlington, Vermont Correspondence: Michael J. Toth, PhD, Health Science Research Facility 126 B, 149 Beaumont Ave., University of Vermont, Burlington, VT 05405. Electronic mail may be sent to michael.toth{at}uvm.edu.
Background: Patients with chronic heart failure frequently
experience profound wasting during the course of the disease, a condition
termed cardiac cachexia. Although protein is the primary structural and
functional component of most tissues, few studies have examined the effect of
heart failure on protein metabolism. Moreover, no study has assessed the
relationship of protein turnover to hormonal alterations thought to promote
cachexia. Thus, our goal was to determine if whole-body protein metabolism is
altered in heart failure patients and to assess the relationship of protein
kinetics to circulating levels of anabolic and catabolic hormones.
Methods:We measured whole-body protein metabolism using
13C-leucine, body composition, and circulating anabolic and
catabolic hormone levels in 10 patients with chronic heart failure and 11
elderly controls. Results: No differences in leucine rate of
appearance, oxidation, or nonoxidative disposal were noted between heart
failure patients and controls. However, in a subgroup of patients
characterized by increased resting energy expenditure for their metabolic body
size (n = 4;
Journal of Parenteral and Enteral Nutrition, Vol. 30, No. 3,
194-201 (2006) This article has been cited by other articles:
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20% above that predicted from fat-free mass), leucine rate of
appearance (mean ± SE; 146 ± 6 µmol/min), an index of protein
breakdown, tended to be higher compared with patients with normal resting
energy expenditure (n = 5; 120 ± 8 µmol/min) and controls (127
± 4 µmol/min; p = .06). Alterations in anabolic/catabolic
hormone balance did not explain increased protein breakdown in this subgroup,
and no correlations were found between hormone levels and protein breakdown in
the heart failure group as a whole. In contrast, increased circulating
interleukin-6 soluble receptor (r = 0.829; p < .01) and
reduced insulin-like growth factor-I (r =–.751; p <
.05) levels were related to greater rates of leucine oxidation in heart
failure patients. Conclusion: Our results demonstrate that, although
increased protein turnover is not a generalized feature of heart failure,
there is a subgroup of patients characterized by resting hypermetabolism and
increased protein breakdown. Moreover, hormonal alterations related to the
heart failure syndrome were related to increased protein oxidation. 
