Laboratory diagnostics – What is the significance of the individual values?
Troponin, NT-per BNP, creatine kinase and, of course, blood fats (cholesterol): We explain what it can mean if one of these values is increased.
What blood tests to take for cardiac screening? Cholesterol, Troponin, NT-per BNP – which test?Everyone knows the laboratory expression from his family doctor. A lot of values, but what does it mean if some values are increased or decreased? What values are important for the heart? Ultimately, all laboratory parameters must always be seen in the context of complaints and other examination results. Your treating physician will explain and interpret the laboratory values in the context.
Nonetheless: in findings reports, doctor’s letters or in the communication with medical staff, there are always concepts which we would like to explain here.
Cholesterol levels: What is total cholesterol, LDL, HDL? What are the values too high?
Cholesterol plays a central role in the body as the central building block of cell membranes and the starting material for the production of hormones, vitamins and bile acids. The cholesterol is largely produced in the body itself. The enzyme β-HMG-CoA reductase is important. This enzyme is inhibited in the treatment with so-called statins, thus reducing the production of body-borne cholesterol. The transport in the body from the liver happens via the LDL cholesterol. Since this transport plays a central role for the deposits in tissue and blood vessels, the LDL is also called “bad” cholesterol. The HDL cholesterol is important for the return to the liver. Therefore, it is also called “good” cholesterol. Why exactly deposits in the vessels comes, is not fully clarified. Disorders in cholesterol metabolism, or defects of receptors (e.g., LDL receptor) are considered to be the cause of the development of atherosclerosis. According to today’s teaching, there is no upper limit for all patients. If there are risk factors for arteriosclerosis or CHD (for example hypertension, overweight, etc.), the limit value for which measures should be taken in the sense of a primary prophylaxis (► arteriosclerosis) is lower than in comparison persons. And vice versa: If vessel changes are already known, or if there is a CHD, “normal” cholesterol values should also be treated. This is because the statins are apparently also based on an anti-inflammatory and antioxidant active component, which can inhibit or even reversibly prevent arteriosclerosis (pleiotropic effects of the statins).
Troponin I and Troponin T
The cardiac troponin (cTN) is a protein complex of the muscle fibers of the heart muscle, which is composed of several subunits. The subunits cTNI and cTNT are important for the diagnosis of heart damage (infarction, myocarditis). For the diagnosis of acute breast pain in acute coronary syndrome (ACS), the troponin is particularly important. It can now be assured with rapid tests in the emergency ambulance or chest pain unit.
Creatine Kinase (CK and CK-MB)
The creatine kinase is an enzyme that can supply energy reserves in body cells, especially in the muscles, in the short term. If elevated values are measured in the blood, this may indicate damage to the muscle. CK is particularly important in the diagnosis of myocardial infarction. The subform CK-MB increases very rapidly (faster than the troponin) in a heart attack. Therefore, the CK-MB is of particular importance in the early phase of an infarction for diagnosis. However, the total CK may also be increased under severe physical stress (e.g., sports), muscle inflammation or disease, but also medication (e.g., cholesterol lower / statins).
The height of the CK-MB value and the course give the treating physician a good orientation about the extent of the damage and the course of treatment. But: The CK-MB is very sensitive, i. When cardiac muscle damage arises, it is usually increased but is not as specific as e.g. The troponin. An increase does not necessarily mean that there is a heart attack. In some patients there are unclear increases in the duration of the CK, which do not have their own disease value. It is important to interpret the values in the context of other laboratory values and test results.
Creatinine – Marker of renal weakness, important before contrast agent investigations
The creatinine is a degradation product that is excreted continuously through the urine. When renal function is severely restricted, the creatinine level in the blood increases. Because x-ray contrast agents can damage the renal function, the determination of the creatinine value as an important value for renal function is important. Therefore, the creatinine value is determined beforehand in a planned examination with contrast medium (e.g., cardiac catheter, cardiac CT angiography).
NT-per BNP marker of heart failure
NT-proBNP is a small protein building block (polypeptide) that acts like a hormone. If the heart muscle is stretched during cardiac insufficiency (heart failure), it is released and caused that saline (NaCl) is excreted through the kidneys and thus fluid is withdrawn from the body. In addition, the smooth muscles in blood vessels are also relaxed and thus the blood pressure is lowered. The detection of NT-proBNP is very specific for the diagnosis of cardiac insufficiency. If it is normal, a heart weakness – e.g. As a cause of dyspnoea. Many doctors use the NT-proBNP also for the follow-up of a therapy with heart failure drugs.
Lipoprotein (a) – Risk Factor for Arteriosclerosis, Heart Attack and Stroke
In addition to cholesterol, lipoprotein (a) is now known as an additional, independent risk parameter. The lipoprotein (a) should be determined in patients with a risk constellation or already present vascular damage. Genetic disorders in fat metabolism can lead to marked changes in the vascular system even in younger years.