CK–MB is one of three separate forms (isoenzymes) of the enzyme creatine kinase (CK). CK–MB is found mostly in heart muscle. It rises when there is damage to heart muscle cells.
Como a amostra é obtida para o exame?
NOTA: Se exames médicos em você ou em alguém importante para você o deixam ansioso ou constrangido, ou se você tem dificuldade de lidar com eles, leia um ou mais dos seguintes artigos: Lidando com dor, desconforto ou ansiedade durante o exame, Conselhos sobre exames de sangue, Conselhos para ajudar crianças durante exames médicos, e Conselhos para ajudar idosos durante exames médicos.
Outro artigo, Siga essa amostra, fornece uma visão da coleta e do processamento de uma amostra de sangue e de uma amostra de cultura da garganta.
É necessário algum preparo para garantir a qualidade da amostra?
Como o exame é usado?
CK–MB levels, along with total CK, are tested in persons who have chest pain to diagnose whether they have had a heart attack. Since a high total CK could indicate damage to either the heart or other muscles, CK–MB helps to distinguish between these two sources.
If your doctor thinks that you have had a heart attack and gives you a “clot-dissolving” drug, CK–MB can help your doctor tell if the drug worked. When the clot dissolves, CK–MB tends to rise and fall faster. By measuring CK–MB in blood several times, your doctor can usually tell whether the drug has been effective.
Quando o exame é pedido?
CK-MB is usually ordered along with total CK in persons with chest pain to determine whether the pain is due to a heart attack. It may also be ordered in a person with a high CK to determine whether damage is to the heart or other muscles.
Increased CK-MB can usually be detected in heart attack patients about 3-4 hours after onset of chest pain. The concentration of CK-MB peaks in 18-24 hours and then returns to normal within 72 hours.
Although CK-MB is a very good test, it has been largely replaced by troponin, which is more specific for damage to the heart.
O que significa o resultado do exame?
If the value of CK-MB is elevated and the ratio of CK–MB to total CK (relative index) is more than 2.5–3, it is likely that the heart was damaged. A high CK with a relative index below this value suggests that skeletal muscles were damaged.
Há mais alguma coisa que eu devo saber?
Severe injury to skeletal muscle can be significant enough to raise CK–MB levels above normal, but such injury doesn’t usually cause a high relative index. Strenuous exercise may also increase both CK and CK-MB.
Sometimes persons who are having trouble breathing have to use their chest muscles. Chest muscles have more CK–MB than other muscles, which would raise the amount of CK–MB in the blood.
Persons whose kidneys have failed can also have high CK–MB levels without having had a heart attack. Rarely, chronic muscle disease, low thyroid hormone (T3, T4, TSH) levels, and alcohol abuse can increase CK–MB, producing changes similar to those seen in a heart attack.
What does heart attack mean?
Heart attack means that some of the muscle in your heart has died. The medical term for this is myocardial infarction (MI). Most commonly, a heart attack starts with a kind of heavy pressure or pain in the chest, often extending into the neck or left arm. You may have trouble catching your breath, or you may feel weak and break into a cold sweat.
A heart attack usually occurs when one of the blood vessels (called coronary arteries) that bring blood to your heart muscle is blocked. This can happen when a blood clot forms in a blood vessel that is already partially blocked. The partial blockage, which develops over many years, is most often caused by too much fat layered in the wall of the blood vessel (this is often called hardening of the arteries—the medical term for this is atherosclerosis).
If I have chest pain, does that mean I am having a heart attack?
Many other problems can cause chest pain, and it is not always possible to tell just from the type of chest pain whether or not you are having a heart attack. Many people have chest pain from straining the muscles in their chest, and chest pain can occur with some lung problems. Chest pain can be a warning sign of hardening of the arteries of the heart (coronary artery disease or CAD). Chest pain that occurs during exercise, hard work, or at times of stress, lasts for a few minutes and goes away with rest is called angina. If the pain lasts longer than just a few minutes, especially if it occurs when you are resting, seek immediate medical attention.
What are the other heart attack tests?
Doctors may use more than one test to determine if a person who has chest pain is having a heart attack. Troponin is generally considered the most accurate test, and CK-MB is also highly accurate in detecting damage to the heart, even when there is no other evidence of a heart attack. Myoglobin and creatine kinase almost always rise in patients with a heart attack, but they are less specific other conditions can also produce an increase in these two tests.
What if I’m not sure I’m having a heart attack?
If you have prolonged chest pain, especially if it does not go away with rest— or if you have been told you have angina and the drugs you were prescribed do not ease the pain—seek immediate medical attention. Many people who have had a heart attack die without ever having tried to call an ambulance or get to an emergency room.