Critically ill patients are exposed to different stressors which may generate Systemic Inflammatory Response Syndrome (SIRS). This situation hinders the assessment of micronutrients status, such as vitamin D or Zinc (Zn), potentially affecting patients' treatment and recovery. The aim of the present study was to assess the evolution of circulating 25-Hydroxyvitamin D (25-OH-D) levels after seven days of Intensive Care Unit (ICU) stay and the influence on changes in plasma and erythrocyte Zn levels, as well as other parameters related to phosphorus-calcium metabolism. A prospective analytical study was conducted on 65 critically ill patients (42% women) aged 31-77 years with SIRS. Total 25-OH-D levels were measured in plasma samples by liquid chromatography-tandem mass spectrometry, and Zn content was analyzed by flame atomic absorption spectrometry. Both 25-OH-D and 25-OH-D3 levels were directly associated with erythrocyte Zn concentration at follow-up (p = 0.046 and p = 0.011, respectively). A relationship between erythrocyte and plasma Zn was also found at this follow-up point. No such clear associations were found when considering 25-OH-D2. Different disturbances in levels of phosphorus-calcium metabolism parameters were found, suggesting a relationship between the changes of 25-OH-D3 levels and parathormone (p = 0.019) and phosphorus (p = 0.005). The findings of the present study suggest an interaction between vitamin D and Zn, in which the correct status of these micronutrients could be a potentially modifiable factor and a beneficial approach in the recovery of critically ill patients.
Keywords: Intensive Care Unit; Systemic Inflammatory Response Syndrome; Zinc; critically ill patient; vitamin D.