TNFRSF11B and COVID-19: There was no correlation between the serum OPG level or DEXA (T-score %) and the serum level of ACE-2, unlike the correlation between the OPG level in the serum and DEXA (T-score %), which was statistically highly significant with a strong negative linear correlation (P-value = 0.001), as shown in Table 2. There was a significant inverse relationship between OPG levels in the serum of post-COVID-19 patients and their DEXA (T-score %) measurement (Figure 1).