Bone turnover markers do not predict stress fracture in elite combat recruits.

BACKGROUND: With bone resorption rates greater than formation, stress fracture pathogenesis plausibly involves bone remodeling imbalance. If this is the case, one would anticipate serum levels of bone turnover markers would be higher in patients with stress fractures than in those without. QUESTIONS/PURPOSES: We therefore asked whether: (1) bone turnover markers differ between soldiers who will or will not have stress fractures during basic training; (2) bone turnover markers change during basic training; and (3) serial bone formation or bone resorption markers differ between subjects with and without stress fractures during basic training?
METHODS: We performed serial determinations of serum bone formation (bone alkaline phosphatase [BAP] and procollagen type I amino-terminal propeptide [PINP]), and resorption (tartrate-resistant acid phosphatase [TRAP5b] and cross-linked collagen telopeptide [CTx]) biomarkers, measured at 2- to 4-week intervals (during 18 weeks) in 69 male soldiers in the Israeli Defense Forces during elite basic training. Twenty-two soldiers (32%) were diagnosed with stress fractures. The mean training week at diagnosis was 8.0±2.0 weeks.
RESULTS: We observed no differences in bone turnover markers between soldiers with and without stress fractures. During basic training, the mean values of all subjects for bone turnover markers (BAP, PINP, and CTx) changed in comparison to their mean levels at induction (43.9 versus 37.3 μg/L, 110.4 versus 78.0 μg/L, 1.4 versus 1.1 ng/mL, respectively). We found no changes in bone formation and resorption markers between subjects with and without stress fractures.
CONCLUSIONS: These specific bone turnover markers cannot be considered as either diagnostic or predictive tools for stress fracture detection in young male military recruits. LEVEL OF EVIDENCE: Level II prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.