The coronavirus disease of 2019 (COVID-19) is an emerging coronavirus that affects people's respiratory systems (Severe acute respiratory syndrome coronavirus) and can the rapidly growing COVID-19 pandemic represents a significant global challenge, It can be considered that lipocalin-2 was highly associated with the severity of COVID-19. Therefore, it may be a useful biomarker for diagnosing disease severity in COVID-19 patients. lipocalin-2  was initially identified as a secreted protein from human neutrophils. Alveolar type II cells that have been damaged primarily express this substance. To verify lipocalin-2's potential as a diagnosing biomarker for COVID-19 patients, Lipocalin-2 levels in the blood were examined in this pilot investigation. To examine the relationship between serum lipocalin-2 levels and the severity of COVID-19 infection to see if this protein may be utilized as a disease indicator. This study was done in a case-control study with One hundred and twenty patients (79 males, 41 females) with COVID-19 who participated in the research. The COVID-19 patients were divided into three groups based on the severity of the illness: critical disease (n = 30), severe disease (n = 30), and mild/moderate disease (n = 60), with (n = 60) healthy volunteers serving as the control group (35 males, 25 females). Between January 2022 and May 2022, the patients were obtained from Al-Amal hospitals and the AL-Shefaa centre in AL- Najaf City, Iraq., All of the patients' fundamental clinical and demographic data were collected along with blood samples. Enzyme-linked immunosorbent tests were used to measure the blood's level of LCN2 (ELISA). The levels of total cholesterol, triglycerides, and High-Density lipoprotein were assessed using colorimetric methods. Ichroma was tested for serum ferritin, D-dimer, and CBC by Swelab. ran a statistical study to see if they were related to the severity of the disease.
    Higher lipocalin-2 levels were observed in the patient group, particularly in cases of mild/moderate (1.32±0.30) (P. 0.001), severe(2.16±0.42) (P. 0.001), and critical(4.71±1.01) (P. 0.001) comparing cases to healthy controls (0.86±0.51) respectively, groupings. ( SPO₂ %, Hb, TC, HDL, LDL, and lymphocyte) levels were found to significant negative correlation with one another in the COVID-19 patient group, with p-values=0.001 for each of these relationships. Moreover, a significant positive correlation between (TG, VLDL-C, WBCs, neutrophil, platelet,  N/L ratio, D-dimer, Ferritin, and CRP, p.value=0.001 for each one of them ) levels with lipocalin-2 in the COVID-19 patients group. a cut-off value of    1.215   (ng/mL) for lipocalin-2  predicted severe COVID-19 with a sensitivity of 81.7 % and a specificity of  80.2 % (AUC:   0.9, 95%CI   0.852-0.949  ; p<0.0001).