Moderate COVID-19 disease is associated with reduced bone turnover.

SARS-CoV-2 infection has been associated with musculoskeletal manifestations, including a negative effect on bone health. Bone formation was found to be reduced in COVID-19 patients. The aim of this case-control study was to determine whether bone metabolism is coupled or uncoupled in COVID-19 patients with moderately severe disease, the latter expressed by the requirement of hospitalization but not intensive care treatment, no need for mechanical ventilation, and a C-reactive protein level of 16.0 [4.0; 52.8] mg/l in serum. Besides standard biochemical markers, serum levels of C-terminal telopeptide of type 1 collagen, tartrate-resistant acid phosphatase, osteocalcin, bone-specific alkaline phosphatase, sclerostin, dickkopf-1, and osteoprotegerin were evaluated in COVID-19-infected patients at the time of hospital admission, along with those of age- and sex-matched non-infected controls. The median age of the 14 female and 11 male infected patients included in the matched-pair analysis was 67 [53; 81] years. C-terminal telopeptide of type 1 collagen was significantly lower in COVID-19 patients (0.172 [0.097; 0.375]) than in controls (0.462 [0.300; 0.649] ng/ml; p=0.011). The patients' osteocalcin levels (10.50 [6.49; 16.26]) were also lower than those of controls (15.33 [11.85, 19.63] ng/ml, p=0.025). Serum levels of sclerostin and dickkopf-1 were significantly higher in infected patients relative to controls. The remaining parameters did not differ between cases and controls. A limitation of the study was that patients and controls were recruited from different hospitals. Nevertheless, due to the geographical proximity of the two centers, we assume that this fact did not influence the results of the study. Given this limitation, the investigation showed that bone metabolism is altered but remains coupled in patients with moderately severe COVID-19. Therefore, it is important to evaluate bone turnover markers and fracture risk in these patients during the post-infection period. This article is protected by copyright. All rights reserved.