IRCT20091012002582N23 IRCT 2021-05-18 Tabriz University of Medical Sciences The effect of selenium administration on complete blood count in elderly patients admitted to critical care unit The effect of selenium administration on complete blood count in elderly patients admitted to critical care unit 2021-05-22 anticipated 60 Complete https://irct.ir/trial/55716 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Randomization description: Initially, the blocks (n=4) with different arrangements of A and B will be defined. Considering the different probable arrangements of A and B, blocks will be numbered from 1 to 6. To enroll the initial 4 patients into the study, one of the arrangements will be selected using the random digit table and the patients will be assigned into the A and B groups accordingly. For the next 4 patients, the arrangement pattern will be selected again and the patients will be assigned to the groups and this cycle will be repeated to achieve our intended sample size. The unpredictability of assignment and balancing the number of patients across the two groups during or at the end of the study are the main advantages of this method. Notably, the patients will be assigned into the study based on the ICU date of admission and nobody will be able to assign the patients to the specific group of interest, Blinding description: The aim of double-blinding is the avoidance of patients and researchers from being informed about the study intervention, so enrollment of patients in groups will not be recognized. The patients will be assigned into the study based on the ICU date of admission and determined series by randomization process ( based on blocks) and the researcher will not be aware of the patient's assignment in the intervention and control groups. The informed consent will be obtained from the patient's next of kin and they will thoroughly be informed about the study but they will be blind about the group in which their patient will be included. 3 Other infectious disease. Intervention 1: Intervention group: Patients in the intervention group will receive bollus administraion of IV selenium (3000 µg) (produced by Biosyn company, Germany) during 3 hours at the beginning, and then they will receive 1500 µg /day during one hour for 10 days. Intervention 2: Control group: Patients in control group will receive normal saline as the same volume and speed for 10 days. No - There is not a plan to make this available Justification or reason for not sharing IPD is No more information