Laboratory markers of bone metabolism in relation to adaptive reserves and musculoskeletal disorders

BACKGROUND: The functions of many bone metabolism markers are crucial to the body’s adaptive responses to stress.

AIM: This work aimed to study laboratory markers of bone metabolism in relation to the state of adaptive reserves and musculoskeletal disorders in employees of the Federal Fire Service of the State Fire Service of the Ministry of Emergency Situations of the Russian Federation.

METHODS: A total of 105 male employees of the Federal Fire Service of the State Fire Service of the Ministry of Emergency Situations of the Russian Federation (mean age, 34.7 ± 0.4 years) were under regular medical checkup. For laboratory assessment, participants were divided into three groups according to the state of the musculoskeletal system and into three groups according to years of professional experience. Serum levels of parathyroid hormone, insulin, and dehydroepiandrosterone sulfate were measured using an Immulite XPi closed-type immunochemiluminescent analyzer (Siemens, USA). Serum cortisol levels and urinary deoxypyridinoline were determined using an Access 2 closed-type immunochemiluminescent analyzer (Beckman Coulter, USA). Serum osteocalcin concentration was measured by enzyme-linked immunosorbent assay (IDS N-MID Osteocalcin). The dehydroepiandrosterone sulfate/cortisol ratio was calculated to assess adaptive reserves objectively, along with the HOMA-IR insulin resistance index and the osteocalcin/insulin index.

RESULTS: Mean values of all studied parameters in all groups were within reference ranges. A decrease in osteocalcin levels (10.89 ± 0.56 ng/mL) was observed in individuals with moderate musculoskeletal disorders compared with the mean level in healthy participants (17.21 ± 1.33 ng/mL). In individuals with a professional experience of 5 years or less, the mean osteocalcin level (18.50 ± 2.15 ng/mL) was comparable to the median of the reference range (19.8 ng/mL) and differed from the lower concentration observed in individuals with a professional experience of 15 years or more. Osteocalcin concentrations were significantly higher in individuals with active depletion of adaptive reserves compared with those whose adaptive reserves were preserved. A decrease in the osteocalcin/insulin index was noted with increasing professional experience and in individuals with musculoskeletal disorders.

CONCLUSION: The results of comprehensive laboratory testing of employees of the Federal Fire Service of the State Fire Service of the Ministry of Emergency Situations of the Russian Federation indicate the absence of pathological changes in bone metabolism markers (exceeding population reference ranges) that are relevant for the diagnosis of clinically manifested musculoskeletal disorders. Nevertheless, the findings confirm the involvement of the musculoskeletal system in multisystem stress adaptation and support the relevance of further investigation of osteocalcin and the osteocalcin/insulin index for early diagnosis of musculoskeletal diseases and for maintaining tolerance to occupational stress in individuals engaged in hazardous professions.