Abstract
Background: Leptin, the newly discovered ob gene product, is synthesized primarily in adipose tissue and circulates to all parts of the body. Injury elicits significant metabolic changes, and it is not known how these changes affect the circulating leptin levels. Methods: Plasma leptin levels were measured in postabsorptive normal subjects (n = 14, 5 men and 9 women) and severely injured (injury severity score [ISS], 34 ± 2), hypermetabolic (resting energy expenditure [REE]/basal energy expenditure [BEE], 1.31 ± 0.04), adult (39 ± 4 years; n = 28, 18 men and 10 women) trauma patients within 48 to 60 hours after injury when they were receiving no nitrogen or calories. The nutritional influence on plasma leptin in these patients was monitored during the subsequent 7 days of total parenteral nutrition (TPN). During TPN the patients were randomized to receive or not to receive recombinant human growth hormone (rhGH) supplementation (0.15 mg/kg/d). Results: Trauma significantly lowered plasma leptin levels, both in women (56%) and in men (68%). Gender dimorphism in plasma leptin levels was seen in normal subjects and in both fasted and fed trauma patients, and in all cases female patients had significantly higher levels. Body mass index showed significantly positive correlations with plasma leptin both in normal and injured subjects. One day of TPN restored normal levels of leptin, both in men and women. Adjuvant rhGH treatment did not show any significant changes over that seen with TPN alone. Conclusions: Decreased plasma leptin levels seen due to trauma may be partly related to the fasting conditions, because 1 day of refeeding restored normalcy. Leptin metabolism in trauma patients seemed to be not altered during rhGH supplementation, suggesting a relatively minor metabolic role of leptin. (Journal of Parenteral and Enteral Nutrition 22:340-346, 1998)
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