Background/Purpose: Inflammatory conditions can exert direct adverse effects on bone metabolism, via increased bone resorption with inadequate compensatory bone formation. COVID-19 has been associated with high levels of inflammation, particularly in patients with severe disease. However, data exploring the impact of COVID-related inflammation on mineral metabolism and skeletal health are scarce. We aimed to explore the relationship between parameters of bone metabolism during acute COVID-related hospitalization and subsequent follow up.

Methods: We carried out a pilot study to analyze serum and plasma samples collected from a subgroup of patients ≥60 years who were enrolled in a larger longitudinal cohort of patients hospitalized with COVID-19 in a single U.S. healthcare system during 7/2020-7/2021. Patients for whom biospecimens were collected during hospitalization were subsequently invited for an in-person follow up encounter at 6-9 months post-hospitalization. IL-6, intact PTH (iPTH), total 25-hydroxy vitamin D (25OHD) and Collagen Type I C-Telopeptide (CTx) were measured at baseline and 6-9 months. Descriptive statistics and Pearson correlation analysis were used to assess the relationship between IL-6 and biomarkers of bone metabolism and turnover.

Results: 12 patients were enrolled in this pilot study with a mean age of 72.6±8 years, and a mean BMI of 35.9±12 kg/m²; 66% were male. Median iPTH levels at the baseline and follow up were 55.2 (IQR 39.5-143.9) and 70.7 (IQR 50.4-111.3) pg/mL, respectively, with 50% of patients evidencing frankly elevated PTH levels both during hospitalization and 6-9 months later. Mean baseline and follow up 25OHD levels were 27±9.2 and 26.5±11.4 ng/mL (p=0.91); mean baseline and follow IL-6 levels were 7.3±3.9 and 5.3±3.2pg/mL (p=0.18) and mean baseline and follow up CTx levels were 0.297±0.189 and 0.467±0.439 ng/mL (p=0.23). Correlation analysis demonstrated a moderate negative correlation at baseline between IL-6 and 25OHD (r=-0.4) and CTx (r=-0.5), and moderate positive correlation between IL-6 and iPTH (r=0.4). There was also a moderate positive correlation between IL-6 and iPTH 6-9 months after hospitalization (r=0.5).

Conclusion: In this study, half of the patients enrolled had increased levels of iPTH both during hospitalization and 6-9 months later. Furthermore, we observed a consistent positive correlation between IL-6 and iPTH levels at both time points. Interestingly CTx levels were inversely correlated with IL-6 levels in our sample, despite elevated iPTH levels. Larger prospective studies are warranted to better elucidate the impact of COVID-19 on bone metabolism.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/relationships-among-parameters-of-mineral-metabolism-and-bone-turnover-during-acute-covid-related-hospitalization-and-subsequent-follow-up-a-pilot-study/