Laboratory tests are tests that are performed by analyzing samples of blood, urine, stool, and body tissues from the body. Care health requires interaction of various disciplines to prevent and cure diseases, in this sense, the laboratory is a contribution to achieve this objective. These tests alone do not diagnose disease, they must be used in conjunction with the patient's medical history. Through this procedure, anemia to infection can be detected, even if the patient does not feel any symptoms of the disease.
Purposes of laboratory tests
Table of Contents
- The main purpose of doing this type of examination is to help specialists and doctors confirm or rule out diseases.
- It is an essential tool for physicians in order to obtain reliable results.
- The doctor may establish a prognosis of the patient's health.
- Detect some kind of complications.
- When there are groups or communities at epidemiological risk, these tests become an essential tool to quickly detect the diagnosis and cure.
The routine tests are described as panels or profiles, used to detect organ function, as appropriate. For example, monitoring through the liver profile, kidney profile, lipid profile, thyroid profile, etc. Other routine tests are those that search for a diagnosis by establishing a pattern of abnormalities such as tumor, hormonal, fertility, drug and hemoglobin electrophoresis markers.
The doctor is in charge of defining the laboratory tests through which the patient's health and chemical status will be monitored, either through blood, urine, feces or body fluids.
Types of lab tests
At present the exams recommended annually are:
- Hemogram: its purpose is to count the elements of the blood, such as red white cells and platelets. These values are of great importance in the development of the immune health system. In patients with Dengue it is very characteristic to see a decrease in white blood cells (leukopenia) and platelets (thrombopenia).
- Urinalysis: this analysis is performed through a few milliliters of human waste (urine), it is a key analysis to detect problems with the urinary system such as infection, diabetes, kidney malfunction, kidney stones, among others.
- Parasitic stool: this test can detect parasites in stool, especially in children. A simple test, through which you can determine the causes of diarrhea in the case of parasites or hidden blood in the stool. Other tests such as cultures (stool cultures) can help with the finding and thus the doctor determine the appropriate treatment.
- Lipid profile: a high risk factor for cardiovascular diseases and arteriosclerosis is high cholesterol. The importance of this analysis lies in evaluating coronary risk factors.
- Liver function: this reflects laboratory examination elevated bilirubin levels equal jaundice (colored yellow skin) may be due to liver problems. The normal value of bilirubin in the blood is 1.3mg / dl, this level increases when there is a destruction of red cells or the liver is not able to excrete the normal amount produced.
- Basic metabolic panel: through this test you can evaluate the levels of glucose, electrolytes (sodium, potassium, carbon dioxide and chlorine). Diabetes is a common disease due to the high level of glucose in the blood, it can trigger a series of fatal disorders in the body, such as diseases of the kidneys and heart.
Thyroid profile: with this test the thyroid gland can be evaluated and in this way confirm or rule out hyperthyroidism. The tests are total T4, free T4, TSH, and T3.
- Pregnant exams: a woman could be pregnant by having a delay in her menstrual period. A blood or urine test can determine whether the suspicions of pregnancy are true. The blood test determines if the woman is pregnant six to eight days after ovulation.
Specialists use two types of laboratory tests to determine pregnancy:
- Qualitative blood test.
- Qualitative hCC blood tests.
During the first trimester of pregnancy, maternal blood laboratory tests help determine the risks of certain defects that the fetus may present. There are two maternal serum (blood) tests, which allow the measurement of two substances that are found in the blood of all pregnant women:
- Determination of plasma protein associated with pregnancy (PAPP-A its acronym in English), these abnormal values are associated with an increased risk of chromosomal abnormality since it is a protein produced by the placenta during the first months of pregnancy.
- Human chorionic gonadotropin (hCG) is a hormone produced by the placenta during the first months of pregnancy and an abnormality in its values also produces a risk of chromosomal abnormalities.
During the second trimester of pregnancy, specifically between weeks 15 and 20, several blood tests also called multiple markers should be included. Among them: Detection of alpha-fetoprotein (AFP) with this test the level of alpha-fetoprotein is calculated, which is a protein produced by the liver of the fetus and is present in the amniotic fluid (that covers the fetus) and passes through the placenta to the mother's blood. Its abnormal values could indicate Down syndrome and other chromosomal abnormalities.
Which tests should be done on an empty stomach
It is very important to respect the fast for the practice of some blood tests, in some cases not even water can be ingested, as it can interfere with the results. Some of the tests that should be performed on an empty stomach are:
- Cholesterol: although for some specialists fasting is not mandatory in this type of test, it is advisable to go 12 hours without eating food to obtain reliable results.
- Glycemia: in this test it is recommended to have at least 8 hours fasting for adults and 3 hours for children.
- TSH levels: it is advisable to fast for at least 4 hours.
- PSA levels: 4 hours fasting is required.
- Lipid tests: this test measures the level of triglycerides, a fat found in the blood and in all cells of the body, so it is recommended to fast between 8 and 12 hours.
During the fast you should not ingest coffee, sodas, any drink that can pass into the bloodstream and alter the results of the tests performed.
It is important to note that every patient who is to undergo surgery and anesthesia must be evaluated with a series of preoperative laboratory tests and cardiovascular evaluations, including:
- Hematocrit and hemoglobin, red blood cell count to rule out chronic anemias.
- Coagulation tests and platelet count are performed to rule out clotting disorders that could increase the risk of bleeding at the time of surgery.
- Blood glucose is suggested to rule out high blood sugar levels and the risk of infections in the operative wound.
- Renal function. (urea nitrogen and plasma creatinine) is performed to verify normal kidney function in the patient.
Most common tests in pediatrics
Pediatricians avoid subjecting children to tests that may be uncomfortable for both them and their parents, so they only perform tests that really cannot be obtained otherwise. Some of these tests are:
- Hemogram. Leukocytes, red blood cells and platelets.
- Coagulation, prothrombin time, cephalic and fibrinogen.
- Hormones, thyroid function, sex hormones, cortisol, etc.
- Liver function, level of AST and ALT transaminases, bilirubin.
- Lipid profile, analyzes the main lipids in the blood, triglycerides, cholesterol.
- Elevation of the ESR, the speed of globular cleavage, of the C-reactive protein, indicates the existence of an infectious or inflammatory process.
Table of normal values of laboratory tests in children
Red blood cell count: it is expressed in HE x 1012 / L erythrocytes and also called red blood cells, they are the most important cells in the blood and their function is to transmit oxygen throughout the body through the lungs and eliminate carbon dioxide that is not necessary.
Hemoglobin HB is a substance that is part of red blood cells and its function is to transport oxygen from the lungs to all tissues of the human body.
Hematocrits Hto. It is a test that is responsible for measuring the amount of red blood cells found in the blood, the hematocrit levels indicate if there are problems with anemia and other medical conditions.
HB (g / dl) Hto%
R born 14.0-19.0 42-60
1 month 10.2-18.2 29-41
6 months 10.1-12.9 34-40
1 year 10.7-13.1 35-42
5 years 10.1-14.7 35-42
6-11 years 11.8-14.6 34-47
12-15 years 11.7-16.0 35-48
