title: Can elevated serum TRACP-5b levels predict stress fractures? A cohort study.
abstract: OBJECTIVE
  Stress fracture is a common overuse injury in athletes and military conscripts. The reliable diagnosis of stress fractures is often difficult, however, because it is usually based solely on radiographic findings. Biochemical markers of bone resorption reflect bone degradation and may also reflect the rate of bone loss. The aim of the study was to examine whether elevated serum tartrate-resistant acid phosphatase isoform 5b (TRACP-5b) levels reflect enhanced bone remodeling and predict the occurrence of stress fractures in military conscripts.
  
  
  METHODS
  Randomly selected military conscripts [mean age, 19.8 (range 18-28) years; n = 820] were followed for 3 months. Baseline blood samples were drawn upon arrival to the service. Four subsequent samples were obtained from subjects that developed stress fractures and one sample each was obtained from two asymptomatic control subjects for each fracture case.
  
  
  RESULTS
  Plain radiography was used to diagnose stress fractures in 20 of the 820 conscripts (2.4%). Follow-up data were available for 14 subjects with 21 stress fractures and 28 control subjects. Subjects with proportionally increasing serum TRACP-5b levels had an 8-fold greater probability of stress fracture than controls. No statistically significant difference was detected.
  
  
  CONCLUSIONS
  Although assessing serum TRACP-5b levels appears to be a promising method to predict bone stress injuries, the present study failed to give a conclusive statement of its usefulness as a diagnostic tool.
authors.affiliation: Centre for Military Medicine, Lahti, Finland. j-p.ruohola@pp.inet.fi
authors.forename: J-P S
authors.initials: JP
authors.lastname: Ruohola
authors.forename: M
authors.initials: M
authors.lastname: Mulari
authors.forename: R I
authors.initials: RI
authors.lastname: Haataja
authors.forename: H K
authors.initials: HK
authors.lastname: Väänänen
authors.forename: H K
authors.initials: HK
authors.lastname: Pihlajamäki
mesh_terms: D000135:Acid Phosphatase / Q000097:blood*; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D017102:Fracture Healing / Q000502:physiology; D015775:Fractures, Stress / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008889:Military Personnel; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007527:Isoenzymes; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase