The 10 Types of Blood Tests
Blood is a liquid connective tissue that circulates through the capillaries, veins, and arteries of living beings. Its red color in vertebrates is due to hemoglobin, a hemoprotein that’s a part of red blood cells and is responsible for transporting dioxygen (O2) to the rest of the body’s tissues. There are various types of blood tests that quantify the efficacy and physiological status of this fluid.
The blood test is one of the first tests performed in the case of any suspicion by a medical professional, as it can show immune, liver, and kidney problems and provides information on (almost) any disease. In the following paragraphs, we’ll show you what types of analytics exist on this front and what their usefulness is at a medical level. Keep reading!
What are blood tests and what are they for?
The National Cancer Institute (NCI) defines blood testing as “a type of test performed on a blood sample to measure the amount of certain substances in plasma or count different groups of cells.” Sometimes this methodology is used to detect signs of disease, but in other cases, it’s part of a routine procedure to check the individual’s health status.
According to the National Library of Medicine of the United States, these are some of the uses of the general blood test:
- A supportive method for diagnosing specific diseases, infections, and conditions. This blood test doesn’t serve to give an answer on its own, but it’s very useful on certain fronts.
- Evaluate chronic conditions that require routine testing, such as diabetes (blood glucose content) and high cholesterol.
- Check that a treatment is working in the short and long term.
- Evaluate the functional status of one or more organs simultaneously. Above all, special emphasis is placed on the function of the liver, kidneys, heart, and thyroid gland.
- Finding out if the immune system is having trouble treating an infection.
Every healthy person should undergo a blood test every year. This is usually accompanied by the relevant physical examination, generally indicated by the company responsible for the patient’s work environment. Unlike what’s believed in some cases, you don’t have to be sick to request an analysis every 12 months.
How is the sample obtained?
Before exploring the types of blood tests, we’re interested in showing roughly how the sample is obtained. The Salud Mapfre portal exemplifies the general process in the following list:
- Go to your assigned health center and ask for a blood test. In most cases, they’ll give you an appointment at the same hospital for a few days later.
- The blood test should be performed after 8-12 hours of fasting, so the sample is always obtained first thing in the morning. Don’t eat breakfast until afterward.
- During the extraction, you’ll be asked to remain seated or lying down (to avoid possible bruising from fainting).
- You mustn’t move during the extraction. Before beginning the procedure, the medical professional will need to locate a vein in the arm for the puncture (almost always the one located on the inside of the elbow joint).
- Once the puncture site has been chosen, the medical professional will place an elastic band over it to promote the filling of the vein.
- The puncture site is disinfected with gauze and alcohol.
- Blood is drawn with a disposable hypodermic needle. Usually, 1 cubic centimeter of blood is sufficient, although sometimes a larger sample is required.
- After the puncture, a sterile dressing and light pressure should be applied until the bleeding stops. This prevents possible infections. If you feel good, you can go home as soon as you finish.
This procedure doesn’t take longer than 1-2 minutes, but then it’s necessary to send the sample to a laboratory. Therefore, the results are usually not ready until at least 24-48 hours later. In addition, your GP must interpret them before making a diagnosis or determining your general health status.
It takes no more than a couple of minutes to get a blood sample.
What are the types of blood tests?
There are several types of blood tests whose distinction goes beyond the puncture and collection of the sample. Below, we’ll show you in detail which are the most important.
1. Complete blood count (CBC)
The complete blood count is the most widely used type of blood test. In it, a set of laboratory tests are used to obtain information on the number, composition, and proportion of the various cellular elements in the blood.
Among them, the following stand out:
- Red blood cells: These are responsible for transporting oxygen to all body tissues thanks to the hemoglobin they contain. There are an estimated 5 million red blood cells per cubic millimeter of blood, 1000 times more than the proportion of white blood cells in the same sample.
- White blood cells: White blood cells or leukocytes are the cells that keep the immune system afloat. Neutrophils represent 62% of adult white blood cells, eosinophils 2.3%, basophils 0.4%, lymphocytes 30%, and monocytes 5.3%.
- Platelets: A platelet is a small, nucleus-less vertebrate blood cell that’s shaped like an oval or round disc and is involved in blood clotting. The normal platelet count is between 150,000 and 400,000 units per cubic millimeter of blood.
- Hemoglobin: Besides the red blood cell count, it’s important to discover the amount of hemoglobin they have. The standard value for adults is between 11.5-14.5 grams/deciliter in women and 13.5-17.0 grams/deciliter in men.
- Hematocrit: Represents the ratio of red blood cells to the amount of blood plasma (non-cellular liquid part). In women, the percentage ranges from 36-46%, while in men it’s 41-53%.
Beyond these general parameters, the red cell indices can also be consulted in the CBC. For example, the mean corpuscular volume (MCV) is obtained by dividing the hematocrit by the number of red blood cells, while the average corpuscular hemoglobin (HCM) is the result of dividing the value of the hemoglobin concentration by the number of red blood cells.
All these parameters are more or less detailed, but they’re used with a specific objective: Controlling the individual’s general state of health. The complete blood count is very useful to detect anemia, autoimmune diseases, immune disorders due to lack of cells, and blood cancers, among many other alterations.
2. Basic metabolic panel (BMP)
As indicated by the Rady’s Children medical portal, the basic metabolic panel is one of the types of blood tests used to detect glucose and calcium levels in the blood, monitor the functioning of the kidneys and assess the electrolyte balance of the body.
Here are the normal values and significance for each:
- Glucose – A blood glucose level below 140 milligrams/deciliter or mg/dL (ideally between 70 and 100) is considered normal. This sugar is one of the major components in the process of obtaining energy within the cell, so its excess in the blood indicates a systemic failure. When the parameter is equal to or greater than 200 mg/dL and there are other criteria, a case of diabetes can be diagnosed.
- Calcium – Calcium is the most abundant mineral in the entire human body. It helps the formation and restoration of bones, but it’s also essential for the transmission of nerve impulses and the performance of movement. Normal blood calcium levels range from 8.5 to 10.2 mg/dL.
- Electrolytes: Sodium, potassium, carbon dioxide, and chloride are electrolytes that help maintain balance in the body. Abnormal levels usually indicate kidney failure, but can also be due to a heart problem or dehydration.
- Blood uric nitrogen (BUN) and creatinine: Both are waste products that are excreted in the urine when kidney function is adequate. Therefore, these values are used to suspect kidney infections, chronic kidney damage, polycystic kidney disease (PKD), and other conditions that affect these purifying organs.
It’s especially important that the patient stop eating (or drinking beverages other than water) 8 to 12 hours before the test. Otherwise, glucose and other nutrient levels may poorly reflect reality at the time of sample collection.
3. Liver function test
As the name implies, these types of blood tests are recommended when liver failure or damage is suspected. Their main purpose is to detect infections (such as hepatitis), monitor the progression of a disease (such as cirrhosis), determine if a treatment is effective, and quantify the possible side effects of taking medications.
Abnormal liver function test results don’t always indicate liver disease, but in most cases, they’re the initial indication that something’s wrong with the liver.
The Mayo Clinic shows us the values that are quantified in this type of analysis:
- Alanine aminotransferase (ALT): This enzyme is part of liver cells, so values above its normal concentration may indicate liver damage due to the destruction of hepatocytes (cytolysis). The normal range is 4 to 36 U/L (international units per liter).
- Alkaline Phosphatase (ALP): Alkaline phosphatase is a hydrolase enzyme responsible for removing phosphate groups from various types of molecules that’s also present in liver tissue. The normal range is 44 to 147 U/L.
- Albumin: This is one of the compounds that’s found in a large proportion in lymphocytes, being the main protein in the blood. Lower than normal albumin levels (below 3.4 g / dL) often indicate liver disease.
There are other compounds that are also capable of indicating the general state of liver health, such as bilirubin, gamma-glutamyl-transferase (GGT), lactate dehydrogenase (LD), and prothrombin. In any case, all the values are obtained in order to quantify the functionality or damage in the liver environment.
4. Complete metabolic panel (CMP)
The full metabolic panel is very similar to the BMP, but there are many more parameters included when creating the patient profile. It also shares several values with the liver function analysis, as in the CMP, we find some of the compounds already named: Albumin, ALP, and ALT, among others.
However, a new parameter is included in the complete metabolic panel: Total protein. The average value is between 6 and 8.3 grams per deciliter of blood (g/dL), although the results can vary greatly depending on gender, age, population, and the type of test used. Levels below normal are especially revealing and indicate malnutrition, malabsorption, and inflammatory conditions.
5. Thyroid panel
The thyroid is a butterfly-shaped glandular tissue located in the neck, in front of one of the cartilages of the larynx. It produces hormones essential for the functioning of the human body and regulates processes such as the rate of caloric burn, the rate of the heartbeat, body temperature, appetite, sleep, and mood.
The thyroid panel seeks to quantify the concentration of hormones produced in the thyroid in the blood. The main values are as follows:
- Triiodothyronine (T3): Normal values for this hormone range from 60 to 180 nanograms per deciliter (ng/dL) or 0.9 to 2.8 nanomoles per liter (nmol/L). Values above or below this range are indicative of hyper and hypothyroidism, respectively.
- Thyroxine (T4): Thyroxine is a hormone that increases the rate of chemical reactions in cells and helps control growth and development. A normal range is 0.9 to 2.3 nanograms per deciliter of blood (ng/dL).
- Thyroid Stimulating Hormone (TSH): This hormone is produced in the pituitary gland and, as its name suggests, stimulates the action of the thyroid. Normal values can range from 0.5 to 5 microunits per milliliter of blood (µU / mL).
As you can imagine, these types of blood tests are mostly used to detect hyper and hypothyroidism.
6. Other types of blood tests
We’ve shown you 5 types of blood tests in detail, but we want to emphasize as a last note that there are many more. In the following list, we’ll show you 5 varieties that are very useful as far as this methodology is concerned:
- Enzyme markers: Enzymes are specific proteins that play different roles at the body level. The excess or deficiency of certain enzyme complexes in the blood can be a sign of disease. Creatinine phosphokinase (CPK-1) levels are the main representatives on this front.
- Testing for sexually transmitted diseases (STDs): Some sexually transmitted pathogens reach the bloodstream, such as the human immunodeficiency virus (HIV). Levels of certain antigens and antibodies indicate infection in the patient.
- Coagulation tests: A low platelet count in the CBC may indicate a bleeding disorder, but there are accessory tests that further refine this profile. The fibrinogen activity test and prothrombin time are very useful in detecting these types of conditions.
- DHEA Sulfate Test: As the name suggests, this test measures the levels of dehydroepiandrosterone sulfate (DHEA) in the blood. Mainly, it’s used to check if the adrenal glands are working properly.
- C-reactive protein analysis: The level of this protein increases in the blood when there’s an active inflammatory process. Normal results are less than 10 mg/L.
The types of blood tests and their peculiarities
Here, we’ve shown you 5 types of blood tests in detail and another 5 more generally. Although the complete blood count and the basic metabolic panel are the most practiced, you must bear in mind that all the mentioned methodologies are useful in the field in which they’re applied.
An atypical result in the blood test (except for the detection of antibodies and antigens) isn’t always a cause for alarm. When interpreting the results of these tests, it’s important to have the help of a medical professional, as self-diagnosis is never an option.It might interest you...
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