Background: We aimed to establish an acute treatment protocol to increase serum vitamin D, evaluate the effectiveness of vitamin D3 supplementation, and reveal the potential mechanisms in COVID-19. Methods: We retrospectively analyzed the data of 867 COVID-19 cases. Then, a prospective study was conducted, including 23 healthy individuals and 210 cases. A total of 163 cases had vitamin D supplementation, and 95 were followed for 14 days. Clinical outcomes, routine blood biomarkers, serum levels of vitamin D metabolism, and action mechanism-related parameters were evaluated. Results: Our treatment protocol increased the serum 25OHD levels significantly to above 30 ng/mL within two weeks. COVID-19 cases (no comorbidities, no vitamin D treatment, 25OHD <30 ng/mL) had 1.9-fold increased risk of having hospitalization longer than 8 days compared with the cases with comorbidities and vitamin D treatment. Having vitamin D treatment decreased the mortality rate by 2.14 times. The correlation analysis of specific serum biomarkers with 25OHD indicated that the vitamin D action in COVID-19 might involve regulation of INOS1, IL1B, IFNg, cathelicidin-LL37, and ICAM1. Conclusions: Vitamin D treatment shortened hospital stay and decreased mortality in COVID-19 cases, even in the existence of comorbidities. Vitamin D supplementation is effective on various target parameters; therefore, it is essential for COVID-19 treatment.

Bone turnover is reported to increase in favour of resorption in overt hyperthyroidism and the rate of resorption is associated with the levels of thyroid hormones. Hypothyroidism, on the other hand, was shown to cause no disturbance of calcium kinetics and found to associate lower trabecular resorption surfaces and increased bone cortical thickness. Similar studies are very rare in subclinical thyroid disorders and consequently we aimed to examine calcium and bone metabolism in subclinical thyroid disorders. Thirteen patients with subclinical hyperthyroidism secondary to untreated Graves' disease, 20 patients with subclinical hypothyroidism and 10 healthy subjects participated in this survey. Briefly calcium, phosphorus, and creatinine (Cre), urinary deoxypyridinoline (U-DPD) and serum osteocalcin (OC) were measured as biochemical markers for calcium metabolism. Concerning serum Ca and phosphorus levels, there were no differences between three of the groups, but urinary Ca excretion was higher in subclinical hyperthyroid patients compared to control and hypothyroid subjects. Hypothyroid patients had similar U-DPD levels with control subjects (p = 0.218). Serum OC and U-DPD were higher in subclinical hyperthyroid compared to control subjects (p<0.001 and p<0.001 respectively). We demonstrated a higher bone turnover and greater calcium excretion in subclinical hyperthyroid patients. Additionally, we found that subclinical hypothyroidism is not associated with disturbed calcium metabolism. As persistent increase in bone turnover is responsible for accelerated bone loss, patients with Graves' disease may have increased risk for osteoporosis.

Objective The risk of primary ovarian insufficiency (POI) increases in association with autoimmune conditions. Adequate intake of vitamin D (vit D) and trace elements is required for the immune system to function efficiently. The aim of this study was to evaluate vit D, zinc, and copper blood levels in women with POI who had given birth to at least one child and in women with normal menstrual cycles. Methods This was a cross-sectional, case-control study involving 63 participants divided into two groups: the study group, which is composed of 35 women with POI, and the control group, which is composed of 28 women with normal menstrual cycles. Serum concentrations of zinc, vit D, and copper were determined for each participant. Results Women with POI had significantly higher serum copper levels and copper-to-zinc ratio but significantly lower serum vit D and zinc levels when compared with the healthy control group. Serum follicle-stimulating hormone levels were inversely correlated with zinc and vit D levels and positively correlated with the copper-to-zinc ratio and copper levels. Vit D levels were inversely correlated with follicle-stimulating hormone levels, copper-to-zinc ratio, and copper levels and positively correlated with zinc levels. Conclusions Most women with POI are deficient in vit D. Zinc, copper, and vit D seem to correlate with hormonal status in the participants. The present study may generate hypotheses for future studies that will investigate the possible mechanisms behind alterations in trace elements and vit D deficiency in women with POI and whether these changes could be used to screen for the risk of developing POI.

Objectives. Our aim was to determine the effect of chronic regular exercise on ischemia-modified albumin (IMA) levels and oxidative stress in type 2 diabetes mellitus (DM). Design and methods. Sixty patients with type 2 DM were randomly divided into two groups as exercise (17 M, 13 F) and non-exercise (12 M, 18 F) groups, each consisting of 30 patients. The exercise group underwent a 3-month aerobic regular exercise consisting of moderate-intensity power walking. The non-exercise subjects remained sedentary throughout the study period. Serum total antioxidant status (TAS), total oxidant status (TOS), and IMA levels of the groups were determined at baseline and 3 months later. Results. There was no significant change in TOS and IMA levels of exercise group but TAS levels were significantly increased (p < 0.05). Also, postexercise systolic (p < 0.001) and diastolic (p < 0.05) blood pressures of the exercise group were significantly lower than the baseline values. In addition, there was no significant change in TAS and TOS levels of the non-exercise group; however, IMA levels were significantly increased (p < 0.01). Conclusion. We have shown, for the first time, that exercise prevents increase in IMA levels in type 2 DM which might have resulted from increased levels of TAS and reduces the risk of ischemia in these patients. These findings show that chronic exercise is beneficial in the prevention of oxidative stress in patients with type 2 DM as documented by decreased IMA levels.