Relationship between tartrate‐resistant acid phosphatase 5b and stress fractures in female athletes

Background Approximately 10% of female athletes have a history of stress fractures, which most commonly occur between the ages of 16 and 17 years old. Purpose We investigated whether tartrate‐resistant acid phosphatase 5b (TRACP‐5b), which is a bone resorption marker, can serve as a valid predictor of stress fractures in female athletes in their teens and 20s. Methods Three hundred and sixteen elite female athletes were recruited between 2013 and 2015. Serum TRACP‐5b and various hormones were examined in blood samples. The serum TRACP‐5b level was compared between athletes with and without stress fractures within 3 months after the initial collection of their blood samples. Results The 316 athletes were divided into two age groups: 13–19 years old and 20–29 years old. Thirty‐six athletes (11.4%) experienced new stress fractures within 3 months after the initial collection of their blood samples. The median serum TRACP‐5b level was significantly higher in teenage athletes with new stress fractures than in teenage athletes without new stress fractures. In univariate logistic regression analysis, the Z‐score of serum TRACP‐5b was a significant predictive factor of stress fractures in teenage athletes only (odds ratio: 1.87; 95% CI: 1.31–2.66; P