|Year : 2019 | Volume
| Issue : 3 | Page : 104-108
Study of ischemia-modified albumin as a biomarker in critically ill patients with sepsis
Y Vishnu Rohit1, Raghu K2, M Shabnum3
1 MBBS Student, Narayana Medical College and Hospital, Chintareddypalem, Nellore, A.P, India
2 Head of Clinical Services, Department of Emergency Medicine, Narayana Medical College and Hospital, Chintareddypalem, Nellore, A.P, India
3 Department of Microbiology, Narayana Medical College and Hospital, Chintareddypalem, Nellore, A.P, India
|Date of Submission||16-Jul-2019|
|Date of Decision||03-Sep-2019|
|Date of Acceptance||19-Sep-2019|
|Date of Web Publication||30-Oct-2019|
Department of Emergency Medicine, Narayana Medical College and Hospital, Chintareddypalem, Nellore, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Background: Critical ill will be accessed by sequential organ failure assessment (SOFA) and acute physiology and chronic health evaluation. Circulating ischemia-modified albumin is generated under ischemic and oxidative conditions and it reflects the disease severity. Aims and Objectives: The objective of this study is to compare the sensitivity and rapidness of Ischemia Modified Albumin as a biomarker with that of an already established biomarker, C-Reactive Protein in patients identified as critically ill septic patients. Materials and Method: A group of 30 subjects were identified using qSOFA as patients suffering from sepsis and their blood samples were taken. These samples were tested for ischemia modified albumin, an inflammatory biomarker, and each sample was also assessed for CRP. Similarly, control patients were assessed for IMA and CRP as well. Results: The results showed that IMA and CRP were both significantly elevated in sepsis, with mean values of 103.77 ± 15.61 ABSU for IMA and 35.58 ± 19.82 mg/L for CRP. However, it was found that the test performed for serum IMA is a quicker and more cost-effective test than that of CRP. Conclusion: This methodology will lead to the usage of a cheaper and more effective diagnostic and prognostic tool for patients succumbed to sepsis.
Keywords: C-reactive protein, critically ill septic patient, ischemia-modified albumin
|How to cite this article:|
Rohit Y V, Raghu, Shabnum M. Study of ischemia-modified albumin as a biomarker in critically ill patients with sepsis. Saudi Crit Care J 2019;3:104-8
|How to cite this URL:|
Rohit Y V, Raghu, Shabnum M. Study of ischemia-modified albumin as a biomarker in critically ill patients with sepsis. Saudi Crit Care J [serial online] 2019 [cited 2019 Nov 12];3:104-8. Available from: http://www.sccj-sa.org/text.asp?2019/3/3/104/270095
| Introduction|| |
Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection  and is a frequent condition encountered in critically ill patients in the emergency room and in the intensive care units (ICUs) of hospitals. It is a debilitating and dangerous condition. In India, nearly a quarter of admissions to ICUs are due to sepsis.
Sepsis is a result of an infection which stimulates the host's defense to an extent where the host's own tissues are damaged. Initially, bacteria are phagocytized by macrophages which secrete pro-inflammatory cytokines activating the innate immunity of the body. White blood cells (WBC) (neutrophils) are recruited to the site of inflammation. The neutrophils and macrophages phagocytize the bacteria and kill them by a combination of several methods by enzymes or respiratory burst producing free radicals and killing the bacteria by lipid peroxidation, formation of cross-links, and damage to DNA.
Normally, these mechanisms are sufficient enough to eradicate the bacteria. However, the bacteria may escape and the inflammatory response might be amplified. Usually, sepsis is due to an exuberant response of inflammation, but it may also be caused due to a severe bacterial infection which causes a strong inflammatory response to match the infection, while also causing “collateral damage.”
In India, ICU mortality, hospital mortality, and 28-day mortality are around 56%, 63.6%, and 62.8%, respectively. The microbial profile of the infectious agents is highly variable. Most of the infections were caused by Gram-negative bacteria (72%). The other agents in descending order of causation are Gram-positive bacteria (12.6%), tropical parasites (7.2%), and fungi (6.2%). Due to this high mortality, it is essential to identify sepsis as early as possible and initiate lifesaving measures.
Sepsis is diagnosed primarily based on several physiological criteria observed in patients. In 1992, at the American College of Chest Physicians/Society of Critical Care Medicine (SCCM) Consensus Conference, the criteria according to the systemic inflammatory response syndrome (SIRS) were described as a clinical expression of the host response to inflammation. These criteria were updated, and sepsis was classified as two or more of the following plus the identification of a foci of infection: temperature >101°F (38.3°C) or <96.8°F (36.0°C); tachycardia >90 bpm; tachypnea >20 breaths/min or PaCO2<32 mmHg; hyperglycemia (blood glucose >140 mg/dL [>7.7 mmol/L]) in the absence of diabetes mellitus; acutely altered mental status; leukocytosis (WBC count >12, 000/μl); leukopenia (WBC count <4000/μl); or a normal WBC count with >10% immature forms. However, it was found that the SIRS criteria were found to have excellent sensitivity, yet a low specificity for sepsis patients and there were chances of missing out of diagnosing a sepsis case.
A 2016 task force convened by national societies including the SCCM and the European Society of Intensive Care Medicine described an easier method termed “quick Sequential Organ Failure Assessment (SOFA)” to facilitate easier identification of patients potentially at risk of dying from sepsis. It assesses 3 criteria and each one carries one point. These are hypotension systolic blood pressure (SBP <100 mmHg), tachypnea (>22 breaths/min), and altered sensorium Glasgow coma scale (GCS <15). A score of 2 points in patients with an identified infection indicates the patient is at high risk and may be septic.
In sepsis, blood samples are also sent to test for biomarkers. C-reactive protein (CRP) is an acute-phase pentameric protein of the pentraxin family of proteins found in blood plasma. The stimulus is usually inflammation due to inflammatory mediators (interleukin [IL-6], transforming growth factor-beta, and tumor necrosis factor-alpha). Its levels rise in response to IL-6 secretion by macrophages and T-cells in inflammation. CRP binds to the surface of dead and dying cells, including bacteria, and helps activate the complement system to facilitate the removal of cells. In healthy adults, the normal concentrations of CRP vary between 0.8 mg/l and 3.0 mg/l. The plasma half-life of CRP is 19 h, and it is constant. The only variable of CRP concentration is any stimulus which increases production from the liver. CRP is mainly used as a marker for inflammation, both in the diagnosis and evaluation of prognosis.
Albumins include a family of globular proteins, of which serum albumin is the major component of blood. The N-terminal end of the albumin protein is usually bound to transitional metals cobalt and copper. It has been theorized that oxidative stress produced by several mechanisms in these pathological conditions (free radicals, hypoxia, acidosis, etc.) causes a conformational change in the N-terminus causing the release of Co and Cu from albumin, leading to the formation of a new form of plasma protein called ischemia modified albumin (IMA). IMA is an emerging biomarker which has been detected in various pathological conditions involving oxidative stress. These include acute coronary syndromes such as myocardial infarction, diabetes mellitus, various liver conditions, chronic inflammatory disorders, rheumatoid arthritis, and other conditions.
As sepsis is a result of the massive activation of the host's inflammatory response, IMA levels should be elevated due to the development of a low pH state and also due to the generation of a high amount of free radicals as a physiological response. Sepsis is a catastrophic state which needs to be detected as early as possible to save the patient from debilitating conditions and death. There are studies which investigate the relationship of IMA and sepsis, as well as many studies involving other biomarkers in sepsis. However, there is a lack of comparison between IMA and existing, frequently used biomarkers like CRP.
Due to the high mortality rate of sepsis, IMA can be proven to be used as a quicker and more accurate method to diagnose and monitor the prognosis of sepsis cases.
The purpose of this study was to evaluate the use of IMA in sepsis. It was to be compared with an existing biomarker, CRP.
| Methodology|| |
The present study “STUDY OF ISCHEMIA-MODIFIED ALBUMIN AS A BIOMARKER IN CRITICALLY ILL PATIENTS WITH SEPSIS” had been carried out in Narayana Medical College and Hospital, Nellore from July 1, 2018, to October 1, 2018 for the duration of 3 months.
The patients who had been diagnosed with sepsis by an intensivist/clinician were admitted in Narayana Medical College and Hospital, Nellore, in the ICU were included in this study. The criteria for selecting the test population included identified SIRS and septic foci, along with a qSOFA score of 2 or above.
Ethical committee approval had been obtained from the Institutional Ethical Committee of Narayana Medical College and Hospital before commencement of the study.
Informed consent was obtained from all the study participants.
The study population includes 33 adult patients who had been diagnosed with sepsis by an intensivist/clinician. However, due to insufficiency of sample size, 3 samples were discarded and 30 samples were used. A control population of 30 age- and sex-matched patients have been included in this study, and a single blood sample has been obtained from them.
Patients with preexisting conditions such as impaired liver function and any hormonal dysfunction have been excluded from the study, as these conditions may alter the IMA levels. Also, pregnant women have been excluded.
A pro forma gathering simple patient variables had been used. The variables include age, patient ID, age, sex, SBP, diastolic blood pressure, respiratory rate, GCS score, respiratory rate, serum CRP, and serum IMA levels.
3 ml of a patient's random sample of venous blood was collected using standard BD vacutainers and taken immediately to the laboratory. Serum sample was separated by centrifugation at 4000rpm for 10 min. The samples were analyzed for CRP (quantitative) and IMA.
Testing for C-reactive protein
Serum CRP was measured using radiometric method using commercial CRP test kit by Radiometer Medical ApS © using AQT90 FLEX analyzer.
Testing for ischemia-modified albumin
IMA was measured by a method developed by Bar-Or et al. using a colorimetric assay based on the measurement of unbound cobalt after incubation of chemicals with the patient serum. This assay is based on the assumption that oxidative stress causes conformational changes in the human serum albumin that are demonstrated by reduced exogenous cobalt (II) binding. Reagents used for testing were 0.1% cobalt chloride, a chromogen dithiothreitol (DTT), and 0.9% NaCl.
To prepare the test solution, first, 50 μL of 0.1% cobalt chloride was added to 200 μL of serum, mixed, and incubated for 10 min at 37°C for sufficient cobalt-albumin binding.
50 μl of DTT, at 1.5 g/l, was added and mixed. After 2 min of incubation, 1.0 ml of 0.9% NaCl was added. A blank solution was prepared by the same procedure except by excluding DTT (the coloring agent). The absorbance of the colored/test sample was measured at 470 nm using a spectrophotometer and compared with the blank solution. The result was expressed in absorbance units (ABSU).
Data analysis was done using Microsoft Excel and Statistical Package for the Social Sciences (IBM SPSS Statistics 20.0; Chicago, IL, USA).
| Results|| |
Thirty-three patients who were clinically diagnosed with sepsis were included in this study. However, due to insufficiency in the sample collected, 3 samples were excluded and 30 samples were used. The mean age of the study population was 53.1 ± 20.26. The mean age of the controls was 56 ± 2.9. The ages ranged from 18 to 83 years.
[Figure 1] shows there were 17 males (56.67%) and 13 females (43.37%) diagnosed with sepsis.
[Figure 2] shows 10 patients in the 18–40 range (34%), four patients in the 41–60 range (13%), and 16 patients in the 61–83 range.
[Figure 3] shows the values of IMA in patients suffering from sepsis versus the control group. The mean value of IMA was 103.77 ± 15.61 ABSU. The controls showed a mean value of 69.8 ± 11 ABSU, P < 0.0001. The IMA levels in the study group were significantly higher than that of the control group by 33.97 ABSU.
[Figure 4] shows the values of CRP (mg/L) in patients suffering from sepsis versus the control group.
The mean value of CRP was 35.58 ± 19.82 mg/L. The controls showed a mean value of 4.8 mg/L, P < 0.0001. The CRP levels in the study group were also significantly higher than that of the control group by 30.78 mg/L.
| Discussion|| |
This study has evaluated the serum IMA levels and CRP levels in 30 patients diagnosed with sepsis through a physiological grading system, qSOFA. Similarly, a control group of 30 patients with similar age- and sex-matched patients were taken, and their blood was evaluated for IMA and CRP as well.
It was observed that there was a male preponderance for septicemia (82.97%) over female (19.14%). Such male predominance was observed in studies done by Shabnum et al. (78.37%), Kondle Raghu and Shabnum  (82.97%) in contrast to higher rates in females as reported by Jung et al. (females – 65.75%).
The distribution in ages had a wide variation, with 10 patients in the 18–40 range (34%), four patients in the 41–60 range (13%), and 16 patients in the 61–83 range (53%) which varied to the findings of Kondle Raghu and Shabnum. which showed 42.54% in the 18–40 range, 40.42% in the 41–60 range, and 17.31% in the 61–83 range.
It was found that the serum IMA levels in this study population were significantly higher than that of the control group, by a mean value of 33.97 ABSU. This was in contrast to the findings of Sahoo et al. which showed a mean elevation of 26.42 ABSU.
The CRP levels of the study population were also significantly higher than that of the control group, by a mean value of 30.78 mg/L. These findings were similar to that of Póvoa et al. which showed an elevation of 20.2 mg/L.
This shows that both serum IMA and CRP are nearly equally effective in the identification of sepsis. However, the test used for serum IMA is a simple test involving basic chemicals and can be done rapidly. The test for serum CRP is a more complicated test involving advanced machinery and techniques. The test for IMA can be done anywhere at subcenters as a quick and affirmative test to diagnose sepsis so cases can be sent to primary care centers due to the availability and low cost of the materials required.
The results have shown that IMA is elevated for sure in sepsis cases, but the prognostic utility as compared to CRP is undetermined as the follow-up data were not available. To demonstrate the prognostic use of this biomarker, a larger sample size and a larger design study are required.
The results agree with the already available literature which shows that IMA is elevated in inflammatory states, as sepsis is an exaggerated state of inflammation. As sepsis involves an overstressed host response, there is a generation of a large quantity of oxygen-free radicals and the generation of a hyperacidic state in the body. This causes the N – terminal of albumin to become a victim to biochemical alteration, resulting in its inability of binding to cobalt and other heavy metals. On therapy, due to control of the hosts' response, there will be a decrease in the free radicals and the homeostatic state of the body will be achieved, so a follow-up study taking values of IMA from blood samples taken throughout therapy can be done.
Sepsis remains as a major cause of admission to the ICU and has a high mortality rate. It is essential to identify and treat sepsis as soon as possible to avoid life-altering consequences in patients. While clinical identification remains to be a major diagnostic tool, a standard confirmatory biomarker is required to treat patients effectively, and to monitor the treatment as well. IMA has been shown to correctly identify sepsis, and on further study, it may be proven to be a gold standard biomarker. However, due to the variety of clinical states that have an exaggerated inflammatory response, the specificity of IMA for sepsis, and how to clinically correlate IMA values with sepsis, remains a field to be explored.
| Conclusion|| |
The findings of the study show that IMA can be used as a novel biomarker in the clinical setting for diagnosing and evaluating the progression of sepsis. It was more rapid, cost-effective, and easier to test for as compared to its another biomarker commonly used, CRP. This is significant as samples taken in subcenters and rural areas can be tested immediately for IMA and sepsis can be identified rather earlier. The patients can be shifted to a primary care center before the disease progresses to an uncontrollable state and avoid life-changing consequences, decreasing the patient mortality and reducing the hospital stay.
However, the limitation of this study was that the sensitivity of IMA in comparison to CRP in sepsis was not evaluated requiring further study. A multicenter study with case follow-ups is required to assess this. To determine its prognostic utility and sensitivity for sepsis, further evaluation is required.
Authors acknowledge to ICMR, Government of India for STS grant: ICMR,-STS- Reference ID: 2018-00060.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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