Plasma Leptin Association with Body Composition and Energy Expenditure in Sickle Cell Disease
Maciej S. Buchowski, PhD, Lorenza A. Simmons, BS, Kong Y. Chen, PhD, Paul J. Flakoll, PhD, FACN, Beverly G. Mellen, PhD, and Ernest A. Turner, MD
Center for Nutrition (M.S.B., L.A.S.) and Comprehensive Sickle Cell Center (E.A.T.) at Meharry Medical College, 1005 D.B. Todd Blvd. and Departments of Medicine (K.Y.C., M.S.B.), Surgery (P.J.F.), and Preventive Medicine (B.G.M.) at Vanderbilt University Medical Center, 21st Avenue South, Nashville, Tennessee
Objective: To examine the association between fasting plasma leptin concentrations and the hypercatabolic state observed in sickle cell disease SCD.
Methods: Plasma leptin concentration and resting energy expenditure (REE) were measured in 37 SCD patients (10 men, 12 boys 14 to 18 years-old, 7 women, and 8 girls 14 to 18 years-old) and in 37 age, gender and fat mass (FM) matched controls. Body composition was measured hydrostatically, REE by whole room-indirect calorimeter, and plasma leptin using an RIA kit.
Results: Plasma leptin concentration and leptin normalized for body fat (ng/dL*kg FM-l) were significantly lower in SCD patients than in non-SCD controls (4.00±3.23 vs. 9.94±14.69, p=0.021 and 0.406±0.260 vs.0.643±0.561, p=0.024, respectively). A positive linear association between log plasma leptin and FM was observed in both males and females, adjusting for age and SCD status. The strength of this association was greater in females compared with males (slope=0.699 and 0.382 log ng/mL per 10 kg FM, respectively; p=0.013). SCD patients on average demonstrated a higher REE, adjusting for FFM (p<0.0001). Log plasma leptin and FM were not statistically significant predictors of REE after adjustment for FFM and SCD.
Conclusions: Once corrected for body composition, mean plasma leptin concentration was significantly lower among female SCD patients than among non-SCD matched controls. Although REE was higher in SCD patients, there is no a simple association between leptin and REE in SCD.