There are several types of blood tests and each one is used to evaluate different parameters. Blood tests are used to evaluate the functioning of organs and glands such as pancreas, liver and kidneys, detect diseases such as cancer, anemia and diabetes, evaluate cholesterol levels, glucose, uric acid, among many other indications.
Blood tests, cholesterol, triglycerides, blood glucose, uric acid, urea, creatinine, HIV and PSA are among the most commonly used blood tests.
Blood count
The blood count is used to blood cells, ie leukocytes (white blood cells), red blood cells (red blood cells) and platelets. The test is used to aid in the diagnosis and follow up on diseases such as anemia, leukemia, infections and inflammation, immunity problems, among others.
Blood Cells
RBCs, also called red blood cells or erythrocytes, carry the oxygen through the bloodstream.
When the level of red blood cells is high, the blood can get "thicker" and impair the functioning of other blood cells. On the other hand, if there is a reduction in the number of red blood cells, it may be a sign of bleeding or anemia.
Leukocytes
Leukocytes or white blood cells are part of the immune system of the body. They are defense cells that protect the body against diseases, inflammation and infections.
If the blood count detects high levels of leukocytes (leukocytosis), it can be an indication of some infectious process, cancer (leukemia), heart attack or even death of some tissue of the body.
Leukopenia is characterized by a low number of leukocytes (leukopenia) and can have several causes, such as viral infections, cancer treatment, mercury ingestion, typhoid, measles, hepatitis, rubella, among others.
Platelets
Platelets act in the blood clotting. The analysis of these cells in the blood count is used to check the blood's ability to coagulate when there are bleeds and to detect the causes of an increase or decrease in the number of these cells.
HIV
The blood test to detect the HIV virus, which causes AIDS, detects antibodies produced by the body to fight the virus. When the test result is "non-reactive", no antibodies against the virus were found in the subject's blood. So the result in this case is "negative" for HIV.
However, the fact that the result is negative does not mean that the person does not have the disease. The results false negatives occur primarily in the early stage of the disease or in the period of the immunological window of HIV.
Learn more at: What is the immunological window of HIV?
When the test result is positive, it is customary to perform another blood test to confirm the diagnosis. This examination is more accurate because it does not detect antibodies, but genetic material of the virus.
Cholesterol
The cholesterol blood test looks at 3 types of cholesterol VLDL, LDL and HDL. The first two are considered "bad cholesterol", while HDL is known as "good cholesterol."
Once LDL and VLDL (bad cholesterol) levels are high, fat plaques may form inside the arteries that can obstruct blood flow, increasing the risk of strokes and heart attack.
HDL is considered "good cholesterol" because it does not form fat plaques and can remove LDL from the circulation.
Learn more at: What is the difference between VLDL, LDL and HDL cholesterol?
Triglycerides
Triglycerides are fats which are also produced by the body. Triglyceride testing is important in assessing the risk of cardiovascular diseases, since when their levels are high there may also be formation of fat plaques on the inner wall of the arteries, just as it does with cholesterol.
If triglycerides, as they are also known, are very high, there may even be inflammation of the pancreas.
It may also interest you: What are triglycerides?
Glycemia
The blood glucose test is used to glucose (sugar) in the bloodstream, being used to diagnose diabetes and other metabolic changes.
When glycemia is above the reference values (hyperglycemia), it can be a sign of diabetes. Already the hypoglycemia is characterized by the low amount of glucose in the circulation and in most cases it is a side effect of treatments with insulin or oral hypoglycemic agents.
Uric acid
Uric acid is a metabolic product of purines, a substance present in cells and part of their genetic material.
An excessive intake of beef and alcoholic beverages may increase uric acid levels and may cause gout episodes. If uric acid is high, it can also lead to kidney stone formation.
Urea
Urea is a product of protein metabolism. It is produced in the liver and eliminated in the urine. The urea blood test helps to evaluate the functioning of the kidneys, since high levels of urea may indicate that the kidneys have lost the ability to adequately filter blood, leading to a build-up of urea in the circulation.
However, the urea test is not very accurate for assessing renal function, since urea may be elevated according to the individual's diet and hydration level, as well as infections, liver diseases, pregnancy, among other diseases and conditions.
When the urea test results are below the reference values, it can be a sign of malnutrition, low protein intake, liver failure, gestation, other diseases and conditions.
Since blood urea levels may be high or low in a variety of situations, it is common to order this test together with the creatinine test, which is more accurate in assessing kidney function.
Creatinine
Creatinine is the result of the degradation of a substance present in muscles. The more muscle mass the person has, the greater the amount of creatinine in the circulation.
A good part of the creatinine is filtered in the kidneys, so this blood test is used to evaluate the filtration capacity of the kidneys. If renal function is reduced, the results will show elevated creatinine levels.
It may also be of interest to you: What are the creatinine reference values?
PSA
The PSA blood test is to detect diseases or prostate, such as cancer, infections, enlargement of the gland and traumas.
PSA is the acronym for Prostate Specific Antigen. It is produced in the prostate and is normally present in the bloodstream. When there is a change in the gland, PSA levels become high.
PSA examination associated with rectal examination is the most effective way of detecting prostate cancer in the initial stages.
Learn more at: What are the benchmarks of PSA?
All blood tests should be interpreted by the doctor who requested them, along with the signs and symptoms presented, the medical history and other tests when necessary.
