IMA
At a Glance
Why Get Tested?
To help rule out myocardial ischemia in a person with chest pain
When to Get Tested?
When you have had chest pain for a few minutes to a few hours and your doctor wants to better determine if you have had or are having a heart attack
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
This test measures the amount of ischemia-modified albumin present in the blood. Albumin is a protein produced by the liver. Making up about 60% of the protein in the blood, albumin helps regulate blood vessel fluid levels and transports compounds throughout the body. When myocardial ischemia, a decrease in blood flow and oxygen supply to the heart, occurs it changes some of the albumin molecules. Within a few minutes, and persisting for several hours, ischemia decreases albumin's ability to bind to metals such as cobalt. The discovery of this property led to the development of a test that measures the amount of ischemia-modified albumin by measuring the reduction in metal binding.
Myocardial ischemia may be caused by the partial or complete blockage of a blood vessel or by a narrowed or constricted blood vessel. A blockage can decrease or prevent blood flow to the heart. It can cause a heart attack (myocardial infarction, MI) and permanently damage or kill heart muscle cells.
Temporary myocardial ischemia may be seen with angina, an episodic condition associated with the gradual narrowing of one or more blood vessels and with arterial spasms. Angina is triggered when the body cannot respond adequately to increased oxygen demands, and it usually resolves with rest. In some cases, angina can become unstable, occurring at rest or becoming more severe, and can escalate to cause a heart attack. Both unstable angina and MI are collectively known as acute coronary syndrome (ACS). Symptoms vary but may include chest pain and pressure that occurs at rest or persists despite rest, shoulder pain, neck pain, nausea, and shortness of breath.
People with these symptoms are typically evaluated in the emergency room. There, the doctor must try to rapidly differentiate ACS from other conditions with similar presentations and try to distinguish between the various causes of ACS. To do this, he may order cardiac biomarkers, tests such as troponin and myoglobin, to detect damage to the heart, and an electrocardiogram (ECG) to look for heart damage. If these tests are clearly abnormal, then the person is started on treatment for MI.
If the tests are not definitive, then determining whether someone is experiencing temporary angina, is at a significant risk of having a heart attack in the near future, or if they can be safely sent home can be a challenge. Researchers are looking for tests that can help guide the doctor's decision-making in this situation. The ischemia-modified albumin test is a potential candidate for this role.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
Ischemia-modified albumin (IMA) is a fairly new test that has been FDA approved to help rule out cardiac ischemia in people with chest pain whose diagnosis is not clear. It is a cardiac biomarker that is meant to be ordered along with or following a troponin test and an ECG.
If the troponin test, which may take several hours to start to increase after an MI, is negative and the ECG is not definitive, then the ischemia-modified albumin test may add valuable information about whether cardiac ischemia is occurring. IMA may be ordered along with a myoglobin test in the first few hours of chest pain to try to stratify the person's risk of having a heart attack in the near future.
When is it ordered?
IMA may be ordered along with or following a troponin, ECG, and sometimes a myoglobin test when someone has chest pains that began within the last few hours and the doctor wants more information about whether the symptoms may be ischemia-related.
What does the test result mean?
Ischemia-modified albumin is a marker of decreased oxygen availability. Studies have shown IMA to be sensitive for ischemia but not very specific, which means that it can be elevated with ischemia in other areas of the body. Its primary value is in its negative predictive value.
When IMA is not present in a person who has been having chest pain for a few minutes to a few hours, then it is unlikely that ischemia has occurred. When IMA and myoglobin are negative, an ECG is normal, and a troponin is negative at initial and repeat testing, then it is unlikely that the person's chest pain has or will result in a heart attack in the near future.
If someone has been experiencing chest pains for several hours, then the IMA test may not be as valuable because it may have already risen and fallen back to normal or near normal levels by the time the blood sample is collected.
Is there anything else I should know?
Research and current studies are evaluating whether a significantly elevated IMA may be useful as a positive indicator that myocardial ischemia is occurring. Increases in IMA have also been seen with ischemia that is occurring in other parts of the body, such as the skeletal muscles and gastrointestinal tract.
The IMA test is not widely used at present. Although it is regarded as a promising cardiac biomarker, its ultimate clinical utility has yet to be determined. Many physicians are adopting a wait-and-see attitude. They want to see more data accumulated on its use and on the factors, such as underlying diseases and decreased albumin levels, that may affect or interfere with its interpretation.
Common Questions
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Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 640-641.
Schreiber, D. and Miller, S. (Updated 2009 July 8). Use of Cardiac Markers in the Emergency Department. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/811905-overview through http://emedicine.medscape.com. Accessed October 2009.
Talwalkar, S. et. al. (2008). Ischemia Modified Albumin, a Marker of Acute Ischemic Events: A Pilot Study. Annals of Clinical & Laboratory Science 38:132-137 [On-line abstract]. Available online at http://www.annclinlabsci.org/cgi/content/abstract/38/2/132 through http://www.annclinlabsci.org. Accessed October 2009.
Christenson, R. Editor (© 2007). LMPG, Biomarkers of Acute Coronary Syndromes and Heart Failure. The National Academy of Clinical Biochemistry [On-line information]. PDF available for download at http://www.aacc.org/SiteCollectionDocuments/NACB/LMPG/ACS_PDF_online.pdf through http://www.aacc.org. Accessed October 2009.
Sources Used in Previous Reviews
Anwaruddin, S. et. al. (2005 January 10). Ischemia-Modified Albumin Improves the Usefulness of Standard Cardiac Biomarkers for the Diagnosis of Myocardial Ischemia in the Emergency Department Setting. Medscape, from Am J Clin Pathol 123(1):140-145, 2005 [On-line journal]. vailable online at http://www.medscape.com/viewarticle/496984?src=search through http://www.medscape.com.
Wu, A. (2003 June). The ischemia-modified albumin biomarker for myocardial ischemia. Medical Laboratory Observer, Clinical Issues Vol. 35, No. 6 [On-line journal]. Available online at http://www.mlo-online.com/articles/mlo0603cliniss.htm through http://www.mlo-online.com.
Titus, Karen. (March 2004) The Latest on IMA Levels, High and Low. CAP Today. [[On-line journal]. Available online at http://www.cap.org/apps/docs/cap_today/feature_stories/0304IMA.html through http://www.cap.org.
Faix, J. (2005 December 1). Conference Report Highlights of the XIX International Congress of Clinical Chemistry. Medscape Pathology 2005;1(2) [On-line information]. Available online at http://www.medscape.com/viewarticle/516609?src=search through http://www.medscape.com.
Sinha, M. et. al. (2004). Role of "Ischemia Modified Albumin," a new biochemical marker of myocardial ischaemia, in the early diagnosis of acute coronary syndromes. Emerg Med J 2004; 21:29-34 [on-line journal]. Available online at http://emj.bmjjournals.com/cgi/content/full/21/1/29 through http://emj.bmjjournals.com.
Roy, D. et. al. (2004). Ischemia-Modified Albumin Concentrations in Patients with Peripheral Vascular Disease and Exercise-Induced Skeletal Muscle Ischemia. Clinical Chemistry. 2004;50:1656-1660 [On-line journal]. Available online at http://www.clinchem.org/cgi/content/full/50/9/1656 through http://www.clinchem.org.
(2005 Feberuary). Clearing a path for new cardiac markers. CAP Today, Feature Story [On-line journal]. Available online at http://www.cap.org/apps/docs/cap_today/feature_stories/0205Cardiac.html through http://www.cap.org.
Morrow, D. et. al. (2004). Chapter 1 Acute Coronary Syndromes, Biochemical Markers of Ischemia [pp 26-28] NACB LMPG: Biomarkers of Acute Coronary Syndrome and Heart Failure (Draft Guidelines) [On-line information]. PDF available for download at http://www.nacb.org/lmpg/biomark/card_biomarkers_chp1.pdf through http://www.nacb.org.
