Relation between serum creatinine and body mass index in elite athletes of different sport disciplines

Objectives: To document the relation between serum creatinine concentration and body mass index in elite athletes from five different sports, and to study potential differences among athletes performing different sports with different features and requirements. Methods: Before the start of the competitive season, serum creatinine was measured in 151 elite athletes from five different sports: rugby (n = 44), soccer ( n = 27), alpine skiing ( n = 34), sailing ( n = 22), cycling ( n = 24). Pearson's correlation analysis was used to evaluate the relation between serum creatinine and body mass index (BMI). Analysis of variance and unpaired Student's t test were used to compare creatinine concentration and BMI in different sport disciplines. Results: In the whole group of athletes, a positive correlation between serum creatinine and BMI was found (r = 0.48, p<0.001). Significant differences in creatinine concentration and BMI were found between athletes competing in different sports: their mean (SD) values were respectively 1.31 (0.12) mg/dl and 28.83 (2.41) for rugby players, 1.27 mg/ dl (0.10) and 23.10 (1.01) for soccer players, 1.15 (0.11) mg/ dl and 25.8 (1.50) for skiers, 1.08 ( 0.11) mg/ dl and 26.93 (2.36) for sailors, and 0.91 (0.07) mg/ dl and 21.33 (1.21) for cyclists. Conclusions: There is a correlation between creatinine concentration and BMI in elite athletes competing in different sports characterised by different kinds of training, competitive season, and involvement of aerobic and anaerobic metabolism. Interpretation of creatinine concentrations in male athletes should consider professional status as well as the specific sport performed. All athletes should be monitored with consecutive creatinine assessments, using as the baseline the concentration determined before the start of training and the competitive season, but taking into consideration the specific sport performed and the BMI until equations that include creatinine and factors that affect its concentration are used.