0220 Adiponectin is a novel plasma protein which is secreted by adipose tissue and circulates in human plasma at high concentrations. It has been shown that adiponectin has a strong relationship with fat mass, plays a role in regulation of glucose and lipid metabolism and is negatively correlated with glucose, insulin, and BMI. While it has been well established that adiponectin levels increase in amenorrhea associated with anorexia nervosa, it is not known whether amenorrheic athletes present with altered plasma adiponectin levels. PURPOSE: To examine plasma levels of adiponectin in amenorrheic and eumenorrheic athletes. METHODS: Blood samples were obtained in a fasted state (12hr) during the early follicular phase (days 2–6) of two consecutive menstrual cycles in eumenorrheic athletes or on day 1 of two consecutive 30-day periods in amenorrheic athletes. Body composition was determined by DEXA. Adiponectin levels were analyzed by ELISA and compared using independent ttests. RESULTS: Amenorrheic (n = 8) and eumenorrheic (n = 22) athletes were similar (p>0.05) with respect to age (24.9±0.9 yrs), height (164.2±0.01 cm), weight (57.5±1.1 kg), lean body mass (42.1±0.9 g), age of menarche (12.5±0.3 yrs) and VO2 max (44±0.9 ml/kg/min). The amenorrheic group approached significantly lower (p<0.06) percent body fat (19.4±1.22.4 vs 24.5±1.4), fat mass (10.4±1.4 vs 13.8±1.0 g), and BMI (20.4±0.6 vs 21.7±0.4) when compared to the eumenorrheic athletes, respectively. Body weight did not change (p>0.05) across the measurement period in either group. BMI was significantly correlated (r = −0.598, p<0.001) to adiponectin corrected for fat mass in both groups. After adjustment for fat mass, adiponectin levels were higher (p = 0.011) in the amenorrheic athletes (1029.8 ± 154.05 μg/L) compared to the eumenorrheic (502.2 ± 38.9 μg/L) athletes. CONCLUSION: Plasma adiponectin levels are disproportionately high in amenorrheic athletes compared to eumenorrheic athletes with similar body weights. These results are consistent with elevated adiponectin levels observed in association with amenorrhea in anorexia patients. Future studies should determine whether adiponectin has a unique association with menstrual status, or reflects a chronic adaptation to low energy availability. Funded by Arthur Thornton Cardiopulmonary Fund.