Iron metabolism and lymphocyte characterisation during Covid-19 infection in ICU patients: an observational cohort study

Abstract

Background: Iron metabolism and immune response to SARS-CoV-2 have not been described yet in intensive care patients, although they are likely involved in Covid-19 pathogenesis. Methods: We performed an observational study during the peak of pandemic in our intensive care unit, dosing Ddimer, C-reactive protein, troponin T, lactate dehydrogenase, ferritin, serum iron, transferrin, transferrin saturation, transferrin soluble receptor, lymphocyte count and NK, CD3, CD4, CD8 and B subgroups of 31 patients during the first 2 weeks of their ICU stay. Correlation with mortality and severity at the time of admission was tested with the Spearman coefficient and Mann-Whitney test. Trends over time were tested with the Kruskal-Wallis analysis. Results: Lymphopenia is severe and constant, with a nadir on day 2 of ICU stay (median 0.555 10 9 /L; interquartile range (IQR) 0.450 10 9 /L); all lymphocytic subgroups are dramatically reduced in critically ill patients, while CD4/CD8 ratio remains normal. Neither ferritin nor lymphocyte count follows significant trends in ICU patients. Transferrin saturation is extremely reduced at ICU admission (median 9%; IQR 7%), then significantly increases at days 3 to 6 (median 33%, IQR 26.5%, p value 0.026). The same trend is observed with serum iron levels (median 25.5 μg/L, IQR 69 μg/L at admission; median 73 μg/L, IQR 56 μg/L on days 3 to 6) without reaching statistical significance. Hyperferritinemia is constant during intensive care stay: however, its dosage might be helpful in individuating patients developing haemophagocytic lymphohistiocytosis. D-dimer is elevated and progressively increases from admission (median 1319 μg/L; IQR 1285 μg/L) to days 3 to 6 (median 6820 μg/L; IQR 6619 μg/L), despite not reaching significant results. We describe trends of all the abovementioned parameters during ICU stay. Conclusions: The description of iron metabolism and lymphocyte count in Covid-19 patients admitted to the intensive care unit provided with this paper might allow a wider understanding of SARS-CoV-2 pathophysiology.

Associations of blood essential and toxic metal(loid)s with both disease severity and mortality in patients with COVID-19: a retrospective study

“…Serum iron level was reported as a potential predictor of COVID-19 severity and mortality [29]. Decreased serum iron level could predict the transition of COVID-19 from mild to severe and critical illness [30,29], which was in agreement with our ndings. Zinc is one of the micronutrients that could be consumed to reduce the intensity of SARS-CoV-2 infection and perhaps lessen the respiratory tract infection through the antiviral actions [7].…”

Current State of Evidence: Influence of Nutritional and Nutrigenetic Factors on Immunity in the COVID-19 Pandemic Framework

“…Regarding the COVID-19 context, iron metabolism is clearly disrupted in SARS-CoV-2 infected patients, especially in subjects hardest hit by the disease [122], consequently anemia [123] or hyperferritinemia are typical manifestations of hospitalized COVID-19 patients. Therefore, optimal iron status may be crucial for better disease prognosis.…”

A Review on the Serum Electrolytes and Trace Elements Role in the Pathophysiology of COVID-19

“…Also, the level of iron elevated in pulmonary fibrosis and iron chelators may inhibit pulmonary fibrosis [36]. On the other hand, it has been reported that COVID-19 patients with acute respiratory distress syndrome have low serum levels of Iron and intubation them [37]. The iron concentration 24 mcg/dl was reported in an 80-year-old patient with COVID-19 [38].…”

“…Iron is needed for some reactions and cellular functions like RNA/DNA synthesis and repairs [10] High level of iron may increase viral infections [36], although it has reported that COVID-19 patients have low serum level of iron [37]…”