Plasma leptin association with body composition and energy expenditure in sickle cell disease

Objective: To examine the association between fasting plasma leptin concent rations and the hypercatobolic state observed in sickle cell disease (SCD). Methods: Plasma leptin concentration and resting energy expenditure (REE) w ere measured in 37 SCD patients (10 men, 12 boys 14 to 18 years-old seven w omen, and eight girls 14 to 18 year-old) and in 37 age, Sender 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-1) were significantly lower in SCD patients than in non-SCD contr ols (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 plas ma 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 com pared with males (slope=0.699 and 0.382 log ng/mL per 10 kg FM, respectivel y: p=0.013). SCD patients an average demonstrated a higher REE, adjusting f or FFM (p<0.0001). Log plasma leptin and FM were not statistically signific ant predictors of REE after adjustment for FFM and SCD, Conclusions: Once corrected for body composition mean plasma leptin concent ration was significantly lower among female SCD patients than among non-SCD matched controls. Although REE was higher in SCD patients, there is no sim ple association between leptin and REE in SCD.