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Aim. The authors aimed at studying creatinine concentrations in elite male athletes of rugby, alpine ski and cyclism, characterized from different Body Mass Index (BMI) to evaluate modifications during the competitions season. Methods. Creatinine was measured by Jaffe method in 44 toplevel athletes (18 rugbyists, 13 skiers, and 13 cyclists) before the start of training and competitions and during the competitions season, three times for rugbyists and skiers, and two times for cyclists.
Results. Creatinine concentrations were related to body mass and were significantly different among the groups of athletes of the three sports. Analysis of variance showed significant differences among groups of athletes practising different sports (P<0.0001). The analysis for repeated measures demonstrated significant differences for rugby (P<0.005) and ski (P<0.02), but not for cycling (P=0.25).
Conclusion. The interpretation of the creatinine concentrations in athletes should take in account the kind of sport practised, the BMI, and also the possible variations during the season. The reference intervals used for general population can not be used for athletes.
Key words: Creatinine - Sports - Body Mass Index.
The concentration of creatinine in serum is since long the most widely used and commonly accepted measure of renal function in clinical medicine.1
However, the use of serum creatinine as an indirect marker of glomerular filtration rate has been criticized because it is also affected by age, gender, race, diet, body mass. It was recentiy suggested that more precise estimation of glomerular filtration rate can be obtained using specific equations that take into account the influence of many other factors potentially affecting serum creatinine concentration.2
The common reference range for creatinine in the general population is 0.7-1.3 mg/dL (62-1 15 µp???/L) for adult males, by using Jaffe reaction in automated systems.3 Reference values used for the general population, including serum creatinine level, are routinely applied to athletes, although it should cause some potential misinterpretations, owing to modifications of die parameters because of physical exercise.
In sports medicine, creatinine is widely used for evaluating general healtii status of athletes, and its urinary level is used for validating antidoping tests.
Few papers have been published concerning the creatinine values in athletes, before and/or during competitions, and no data were found concerning the stability of creatinine concentrations during a whole...