A total of 284 Covid-19 patients were screened and 54 patients who met the inclusion criteria were included in the study. Patients who applied to the Covid-19 outpatient clinics of Baku University Hospital between Jan 28 and Mar 10, those who had lower respiratory tract involvement in computed thorax tomography (thorax CT) and positive real-time reverse-transcriptase-polymerase chain reaction (RT-PCR) test in oro-nasopharyngeal swab were included in the study. Glutamine supplementation is routinely ordered by a physician in the intensive care unit with the consent of the patient or his family and is purchased and used by the patient's family. In this study, patients who consented to use glutamine were considered as the case group and other patients who did not use glutamine were considered as a control group. Twenty-seven Covid-19 patients (10 female, 48.5 ± 9.1) using L-Glutamine and 27 Covid-19 patients (12 female, 48.8 ± 4.6) with similar age, gender, and clinical status were included in the study.
Patients with kidney and liver dysfunction, alcoholism, malignancy, connective tissue diseases, cardiovascular diseases, diabetes mellitus, neurological and psychiatric problems (Parkinson's disease, cerebrovascular disease, delirium, bipolar disorder, depression), or severe disease that cannot be measured their weight or height were excluded from the study. The Sequential Organ Failure Assessment (SOFA) scoring was performed on all patients for evaluating the severity of the disease before the beginning of the study. The patients who had a point of quick SOFA (qSOFA) _2 were also not included in the study. When a patient was classified with or at risk of malnutrition at the beginning or in the following period of the hospital stay, we planned a nutritional care plan and excluded them from the study. The patients whose clinical courses and laboratory parameters worsened through all given treatments were evaluated as severe sepsis according to the criteria of SOFA. Firstly qSOFA was calculated with the blood pressure, respiratory rate, and mental status, if the qSOFA is 2 and/or bigger than 2, the patient was taken to the ICU. SOFA measures individual or aggregate organ dysfunction in six organ systems (respiratory, coagulatory, liver, cardiovascular, renal, and neurologic) in the ICU and mostly predict hospital mortality.
Diagnosis of Covid-19
Thorax CT screenings of all patients were taken at the time of hospital admission. As stated in the guidelines of the Azerbaijan Ministry of Health, an oropharyngeal sample was first taken with a swab, then a nasal sample was taken using the same swab, and placed in the same transport medium for diagnosis. Samples were tested by RT-PCR assay developed from the virus sequence.
Before giving the supplement, 2 cc blood samples were taken from both groups. Then for five days, the case group was given a glutamine supplement at the rate of 0.5 g / kg with a tablespoon of sugar, and the control group was given the same amount of sugar. At the end of the fifth day, blood samples were taken again to test for serum levels of IL1β, tumor necrosis factor-alpha, malondialdehyde, and total antioxidant and malondialdehyde capacity, then all data were analyzed. COVID-19 patients with certain diseases, such as heart and liver disease, and those who were unwilling to cooperate were excluded from the study.
To measure this cytokine, the sandwich ELISA method was used using the human ELISA kit manufactured by Diaclone Company with serial number 950.090.096.
To measure the total antioxidant capacity, RANDOX's RANSOM kit was used according to the recommended protocol by spectrophotometry using an Abbot autoanalyzer at 600 nm. The basis of this measurement is based on the incubation of a special substrate with peroxidase and hydrogen peroxide and the production of a radical substrate cation that produces a stable green-blue color that can be measured at a wavelength of 600 nm. The TAC value is in mmol / l.
To measure hs-CRP protein, Pars test diagnostic kit was used by immunoturbidimetric. According to the kit brochure, first 20 μl of serum with 200 μl of reagent 1 was placed at 37 ° C for 5 minutes, then 200 μl of reagent 2 containing mouse monoclonal and goat polyclonal antibodies against human CRP antibody was added. Absorption was measured at 30 and 90 seconds with the Abbot autoanalyzer at 500 nm in mg / l.
1-beta interleukins were measured by ELISA using Bender Med Systems kits (Vienna, Austria).
After discharging the patients before 5 days before the hospitalization period, according to the present project, the necessary recommendations regarding the use of supplements and placebo were provided to the parents and the patients were followed up to control them in terms of taking supplements.
Glutamine supplementation and nutritional status screening
The patient's nutritional status was investigated with the Nutritional Risk Screening (NRS- 2002) at the hospital admission time. NRS-2002 has two levels such as impaired nutritional status and severity of disease (such as low, moderate, or severe for both of them), with an adjustment for age _70 years. The nutrition status as considering the first level of this screening was evaluated by the variables; Body Mass Index (BMI), weight loss in the last 3 months, and decreased food intake in the last week. The severity degrees of disease as considering the second level of NRS-2002 was defined as absent, mild, moderate, or severe that was converted to a numeric score between 1 and 3 according to recommendations. A total score under 3 suggested no nutritional risk. To obtain all information a data collection sheet was used.
All given meals for this study patients were prepared based on the appropriate guidelines in COVID-19 and consisted of equal protein and calorie contents. To the case group, 10 g L-Glutamine available in powder forms (Resource Glutamine, Nestle) were given 3 times a day with meals.
In this study, a subjective index and an objective index for appetite measurement were considered. A visual analog scale (VAS) was used to quantify a subject's feelings on the desire to eat, hunger, prospective consumption, and fullness (for subjective parameters). To measure the food greasiness degree, food greasiness was added to the VAS. The scale 0–10 was adopted to evaluate the sensation before or after eating, and the higher the scale indicated the stronger the sensation. Based on their experience, the subjects were free to calibrate on each line that best matched how they were.
This study is a case-control study for evaluating the glutamine effect on serum levels of some inflammatory factors and oxidative stress and appetite in COVID-19 patients with respiratory infections. A sample size of n ¼ 29 per group is required to provide 80% power to detect a difference in the mean levels with a significance of 0.05 (2-sided a).
The normal distribution of the data was tested using the one-sample Kolmogorov - Smirnov test. Continuous variables are presented as mean ± standard deviation. Categorical variables are presented as counts. The statistical comparisons were performed using the two-sided Student’s t-test. Categorical variables were compared using the Chi-square test or Fisher exact test for small samples. Values of p _ 0.05 were considered to be statistically significant. The statistical analyses were performed using SPSS 20.0 software (SPSS, Chicago, IL, USA) for Windows.