Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients

This study compared vitamin D [25(OH)D] plasma levels with different health related scores, inflammatory markers, markers of cellular damage and coagulation and lung radiological findings during COVID-19 illness. Patients with low 25(OH)D plasma levels had compromised biochemical and clinical findings reflected by profound immunological involvement. Vitamin D insufficiency and deficiency were common in COVID-19 affected patients; only about 8% of the study cohort had normal 25(OH)D plasma levels. Patients with more severe COVID-19 disease had lower 25(OH)D plasma levels regardless of age.

Fifty-two patients hospitalized in Rome, Italy with polymerase chain reaction (PCR) confirmed COVID-19 infection and with different degrees of lung involvement. 

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• Of the 52 patients enrolled in the study, 52% were women (n=27 female and 25 male) with a median age of 68.4 years (range, 29–94 years). 
• If plasma 25(OH)D was <25 nmol/L, the patient was assigned to Group 1 (mean value 14.13±6.0 nmol/L), and if plasma 25(OH)D >25 nmol/L to Group 2 (53.85±22.0 nmol/L).  
• Twenty-two of the patients were assigned to Group 1 [42.3% (22/52)] and 30 to Group 2 [57.7% (30/52)]. 
• The mean ages of the patients in Group 1 and Group 2 were 77.5±16 years and 68.9±18 years, respectively. 
• Patients in Group 1 with very low plasma 25(OH)D levels had elevated D-dimer values, a higher B lymphocyte cell count, a reduction in CD8+ T lymphocytes with a low CD4/CD8 ratio, more serious clinical findings (e.g., organ dysfunction) and more lung involvement. 

Major limitations of this study include: 

• The small sample size (n=52), 
• Lack of a healthy (non-COVID infected) control group, and 
• Its single-center setting, which does not allow generalization to other populations. 

The data underline a relationship between 25(OH)D plasma levels and different serum markers of disease. Without more data, however, it is difficult to argue if 25(OH)D supplementation can play a role in fighting the severity of the disease or reducing its mortality.

• Vitamin D serum levels were measured at admission to the hospital (Sant’Andrea Hospital in Rome, Italy) during the acute phase of the disease and prior to starting any kind of therapy.  
• At the same time, different markers of inflammation [(high-sensitivity C-reactive protein (hs-CRP) and procalcitonin (PCT)], cellular damage (hypersensitive troponin I, creatine kinase myocardial band and lactate dehydrogenase) and coagulation (prothrombin time, fibrinogen and D-dimer) were assessed. 
• Lymphocyte phenotypes were assessed by flow cytometry.  
• Chest computed tomography (CT) scans were performed on all patients and the results were quantified using the pulmonary inflammation index (PII), a modified semi-quantitative scoring system used to quantitatively assess pulmonary involvement in all patients according to lung lesion distribution and size. 

Ricci, A., Pagliuca, A., D’Ascanio, M., Innammorato, M., De Vitis, C., Mancini, R., Giovagnoli, S., Facchiano, F., Sposato, B., Anibaldi, P., Marcolongo, A., De Dominicis, C., Laghi, A., Muscogiuri, E. and Sciacchitano, S. (2021) ‘Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients’, Respir Res, 22(1), pp. 76.