Baume, N., Avios, L., Cauderay, M. Dvorak, J., Mangin, P., & Saugy, M. (2004). C13-labeled Nandrolone excretion in trained athletes: Effect of exercise. Medicine and Science in Sports and Exercise, 36(5), Supplement abstract 1157.

This study evaluated the effect of exercise on urinary excretion of Nandrolone metabolites. Ss (N = 36) were divided into two groups. One group (N = 24) was given two oral does of 25 mg of radio-labeled C13-Nandrolone (to differentiate it from endogenous Nandrolone). The remaining Ss (N = 12) were given placebos. Eight exercise efforts were performed over three weeks, two taking place before the treatments. Each S collected a spot urine sample before and after exercise and five days following the treatment.

The elimination pattern of exogenous Nandrolone showed that the 19-norandrosterone (NA) to 19-noretiocholanolone (NE) ratio was not appropriate for diagnosing the type of excretion (endogenous production or exogenous application) because of the large variability and distribution within the group. Each individual displayed different kinetics and metabolism of the substances. Consequently, measured values of Nandrolone metabolites after exercise are particularly unreliable for they do not reflect the true presence of endogenously or exogenously stimulated production.

Implication. The effect of exercise on the excretion of Nandrolone metabolites is much more complex and unpredictable than previously thought. Nandrolone testing through urinary analyses should not be used to infer anything about an exercising athlete's source of Nandrolone metabolites.

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