What Is a Complete Blood Test? When Do We Need Them?

List of Some Other Blood tests necessary for diagnosis.

Whether you are going for a routine medical checkup or for any specific condition, you might have been suggested to go for a blood test. Routine blood testing is among the most essential methods to monitor your overall physical health. Regular testing can provide insight into your body’s changes over time and empower you to make informed decisions about your health. In this article, we will be covering the most prescribed blood tests.

What Are Blood Tests?

Blood tests are used to measure or examine blood cells, chemicals, proteins, and other components. Blood testing usually referred to as bloodwork, is one of the most popular forms of laboratory procedures. Blood tests are often part of a routine examination. Also, blood tests are used to:

  • For the diagnosis of bleeding and clotting issues.
  • Check your immune system’s ability to combat infections.
  • Monitor chronic medical problems, such as excessive cholesterol or diabetes.
  • Check the function of various organs including the liver, kidney, heart, and thyroids.
  • Aid in the diagnosis of certain diseases and disorders.
  • Determine if treatment for an illness is productive.
The procedure of Blood Testing:blood testing

A health care practitioner will get blood samples from patients. It is also known as blood draw. When blood is drawn from a vein, the procedure is known as venipuncture. One may feel a little pinch when the needle is inserted or removed. This often takes around five minutes. During venipuncture, you may have little discomfort or bruising at the site where the needle was inserted, but these symptoms often subside rapidly.

There are several kinds of blood testing. Common ones include the following,

1. Complete Blood Count.

One of the most often requested types of blood tests is the CBC. The complete blood count test examines the total number of all cell types in the blood. It also gives significant information on various factors associated with each blood cell type. Usually, it consists of the following:

  • White Blood cell count (WBC or leukocyte count): The body’s defense against infection is provided by white blood cells. These cells are less in number than RBCs but, when a person is infected with germs, the number of white blood cells rapidly increases. Measuring the number of white blood cells may help diagnose an infection or monitor how the body is responding to cancer therapy.
  • White Blood cell types (WBC differential): Neutrophils, lymphocytes, monocytes, eosinophils, and basophils are the primary kinds of white blood cells. This test also includes band neutrophils, which are immature neutrophils. Each cell type performs a unique function in the body’s defense. Too many or too few white blood cells may assist diagnose infections, allergic or toxic reactions to drugs or chemicals, and leukemia.
  • Red Blood Cells or RBC Count: Red blood cells transport oxygen from the lungs to the body. They transmit CO2 to the lungs for exhalation. If your red blood cell count is too low (anemia) body won’t get O2, or too high (polycythemia) there is a danger that the cells would clump together and obstruct small blood arteries (capillaries) This makes it difficult for your body’s red blood cells to transport oxygen.
  • Hematocrit (HCT, packed cell volume, PCV): This test evaluates the space (volume) occupied by red blood cells in the blood. The number is expressed as a percentage of red blood cells per unit of blood volume. A hematocrit of 38, for instance, indicates that 38 percent of the blood’s volume is composed of red blood cells.
  • Hemoglobin (Hgb): The molecule hemoglobin fills red blood cells. It transports oxygen and gives red blood cells their color. This lab test examines the quantity of hemoglobin in the blood. It is an excellent indicator of the blood’s ability to transport oxygen throughout the body.
  • Blood Indices. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) are the three red blood cell indices. MCV indicates the size of red blood cells. The MCH number represents the quantity of hemoglobin in a red blood cell on average. The MCHC measures the hemoglobin concentration in a typical red blood cell.
  • Red cell distribution width (RDW. A red cell distribution width (RDW) test evaluates the variations in the red blood cells’ volume and size (erythrocytes).
  • Platelet count: Platelets are the smallest form of blood cell (thrombocytes). They play a vital role in blood clotting. Insufficient platelets may cause uncontrollable bleeding. Too many platelets might cause a blood vessel clot. Platelets may cause artery hardening (atherosclerosis).
  • Mean platelet volume (MPV): Mean platelet volume is a measurement of the average volume of platelets. In conjunction with platelet count, MPV is used to identify certain illnesses. Even if the platelet count is normal, the MPV may be too high or low.

Following are the normal rages for both men and women (where applied)

blood test CBC

2. Blood Type Testing.

Blood typing is a process for determining the kind of blood a person has. The purpose of blood typing is to ensure the safety of blood donation and transfusion. It is also performed to determine whether you have Rh factor on the surface of your red blood cells. Before a transfusion or when determining a person’s blood type for donation, blood typing is performed. To guarantee that patients obtain the correct blood type following surgery or an accident, blood typing is a simple and rapid method.

Certain proteins in red blood cells determine blood type and are totally hereditary. Blood is often categorized using the ABO blood type method. Four primary blood types include:

  • Type A
  • Type B
  • Type AB
  • Type O

If a person obtains red blood cells containing antigens that are not previously present in their system, their body will reject and fight the new red blood cells, according to the American Red Cross.

Blood types are further classified based on the Rh factor:

  • Rh-positive: Individuals with Rh-positive blood have Rh antigens on the red blood cell surface. Rh-positive individuals may receive either Rh-positive or Rh-negative blood.
  • Rh-negative: Individuals with Rh-negative blood are devoid of Rh antigens. People with Rh-negative blood can only accept Rh-negative blood transfusions.

The ABO and Rh blood grouping systems establish your entire blood type. There are eight kinds possible:

O-positive O-negative
A-positive A-negative
B-positive B-negative
AB-positive AB-negative

Your blood type may be identified within minutes. Once your blood type is determined, you are able to give blood and receive transfusions from donors with compatible blood types.

3. Differential Blood Tests.blood tesing

A differential blood test allows a physician to determine the number of white blood cells in the body. There are five types of white blood cells, and the test also indicates the quantity of each type. The findings give information on the state of an individual’s immune system and how it reacts to illnesses and other stressors.

They are required by a doctor for confirmation of a diagnosis, for mild conditions such as flu and urinary infections. Or they may be screening for a persistent problem like an autoimmune or bone marrow issue. A differential blood test may suggest white blood cell issues, but it’s not the only lab test physicians employ. For test purposes, blood is collected from an arm or finger vein for the test. The blood differential test may reveal defective or immature cells. It may also identify an infection, inflammation, leukemia, or an immune system problem. The following types of cells are considered in this lab test,

  • Eosinophils: Parasites can cause infections, and these are used to treat them. Eosinophils also control how the immune system responds to allergic reactions.
  • Monocytes: Monocytes and neutrophils are similar. Typically, they eliminate microorganisms that cause persistent illnesses. Additionally, monocytes contribute to the restoration of damaged tissues.
  • Neutrophils: Neutrophils are the most abundant white blood cells, according to the American Association for Clinical Chemistry. They are in charge of killing bacteria in damaged or sick tissue.
  • Basophils: The least common types of cells present with a small role in allergic reactions and with asthma attacks.
  • Lymphocytes: There are three distinct lymphocyte types. B lymphocytes produce antibodies to combat certain viruses, bacteria, as well as other foreign invaders. T lymphocytes aid in the identification of cells requiring an immune response. The third class of cells, natural killer cells, eliminate cancer cells and viruses.

The American Academy of Pediatric Dentistry suggests that healthy people have the following amounts of white blood cells:

Eosinophils:  1–4 %
Monocytes: 2–8%
Neutrophils: 40–60%
Basophils: 0.5–1.0%
Lymphocytes: 20–40%

4. Clotting Panel.

The purpose of blood clotting tests is to detect and evaluate bleeding disorders, as well as to monitor patients on warfarin or other anticoagulant medications. Clotting problems may cause serious bleeding (hemophilia) or excessive clotting (thrombophilia). Your doctor may prescribe coagulation testing if you have a clotting condition.

The clotting process stops excessive bleeding after a wound. However, the blood in your vessels should not clot. These clots may migrate via your circulation to your heart, lungs, or brain if they develop. This might result in a heart attack, a stroke, or even death. There are several coagulation tests available. The sections that follow have explanations for some of them.

During a coagulation blood test, a blood sample is submitted to the lab to detect any abnormalities in platelet or blood clotting agent levels. No special requirements are necessary for this blood test. The following results are obtained after testing.

coagulation blood test
Image Source:

5. Erythrocyte Sedimentation Rate (ESR)

The erythrocyte sedimentation rate (ESR) is a kind of blood test that evaluates the rate at which red blood cells (erythrocytes) settle to the bottom of a test tube containing a blood sample. This test’s blood sample is measured over the duration of one hour. (ESR) may be recommended by your doctor if they feel that your body is inflamed. A high rate of settling indicates excessive inflammation such as Rheumatoid arthritis, heart diseases, bowel problems, and vascular conditions.

Two methods are used to measure ESR level.

  • Westergren method: It’s the most common ESR technique. Blood is drawn into a Westergren-Katz tube to 200 millimeters (mm).
  • Wintrobe method: Wintrobe is identical to Westergren, except the tube is 100 mm long and narrower.

Normal ESR results are,

Normal ESR test results Abnormal ESR test results
Females under 50 between 0 and 20 mm/hr. greater than 20
Males under 50 between 0 and 15 mm/hr. greater than 15
Females over 50 between 0 and 30 mm/hr. greater than 30
Males over 50 between 0 and 20 mm/hr. greater than 20
Children between 0 and 10 mm/hr. greater than 10

6. Blood Tests for Inflammatory Markers.

Certain kinds of additional proteins are often produced from the site of inflammation and flow in the circulation if a section of the body is inflamed. Blood tests are used by healthcare providers to determine whether a patient is experiencing inflammation. The tests are not highly specific, and several disorders may alter blood test results. To determine the actual source of the issue, more investigation may be necessary.

Blood tests for Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), and Plasma Viscosity (PV) are often used to identify an increase in blood protein levels. In this manner, they serve as indicators of inflammation.

  • Plasma Viscosity (PV): The viscosity, or ‘thickness,’ of the blood may be evaluated using plasma viscosity measurements. Plasma (the liquid portion of the blood) viscosity is altered by the presence of proteins that may be generated naturally in response to infection or inflammation or abnormally in some disorders (paraproteins). Measuring the viscosity of blood may be used to indirectly identify and monitor inflammation, as well as help in the diagnosis and monitoring of a variety of diseases.
  • C-Reactive Protein (CRP): The c-reactive protein (CRP) test examines the amount of CRP in the blood. CRP is a liver-produced protein. It is released into the circulation as a result of inflammation. If you have been damaged or infected, inflammation is your body’s method of defending your tissues.
Erythrocyte sedimentation rate (ESR) The normal range is 0-22 mm/hr for men & 0-29 mm/hr for women
Plasma Viscosity (PV) The normal range for adults is 1.50-1.72 mPA
C-Reactive Protein (CRP) less than 3 to 10mg/L.

7. Enzyme Blood Testing.

This blood test measures the level of different enzymes present in a person’s blood. Enzymes are complex proteins that promote chemical processes in the body. They help digest food so the body can utilize it. They help to coagulate blood as well. Diseases of the musculoskeletal system, organ damage, and traumas may result in the release of enzymes from cells into the blood. The physician could refer to enzyme indicators as biomarkers (biological markers). This biomarker is a disease’s quantifiable indication (medical symptom).

The main forms of enzyme markers are

CPK isoenzymes:

The CPK isoenzymes test analyses the blood level of creatine phosphokinase (CPK). The heart, brain, and skeletal muscles all contain CPK enzymes. CPK levels fluctuate according to age, gender, and ethnicity.

Three varieties of CK enzymes exist:

CK-MM, mostly present in skeletal muscles
CK-MB, mostly present in the cardiac muscle
CK-BB is predominant in brain tissue.

In adults, a CPK level of 200 units per liter (U/L) or less is considered normal.

Cardiac Enzymes

After a cardiac attack, damaged heart enzymes progressively enter the circulation. Emergency department patients with heart attack symptoms are tested for blood proteins. CPK-2, also called CK-MB, may be checked. This particular marker increases significantly during a heart attack.

  • Peptides. may indicate cardiac strain due to heart failure. Healthcare professionals may do natriuretic peptides testing (NPs). Or, you may have A-, B-, or C-type atrial natriuretic peptide (ANP, BNP, or CNP) or N-terminal proBNP testing (NT-proBNP).
  • Troponin test. A troponin test determines the concentration of troponin in the blood. Troponin is a kind of protein that is present in the heart’s muscles. Troponin is not often present in the blood. When cardiac muscle injury occurs, the troponin protein is released into the circulation. As cardiac damage worsens, more troponin is released into the bloodstream. Young and healthy individuals often have little or no cardiac troponin in their blood. According to the American Heart Association (AHA), this is the optimal biomarker for detecting a heart attack.
  • Ischemia-modified albumin (IMA). It is symptomatic of myocardial ischemia. This problem with blood flow in the heart may be caused by coronary artery disease (CAD) or coronary spasm.
  • Myoglobin. This is a tiny oxygen-storing protein. It is measured irregularly. Myoglobin is occasionally tested with troponin to aid in the diagnosis of a heart attack. Additionally, it is not highly specific for detecting a heart attack.
Liver Enzymes:

Enzymes in the liver accelerate chemical processes in the body. Among these chemical processes are the production of bile and chemicals that aid in blood clotting, the digestion of food and toxins, and the defense against infection. Learn more about them in this article.

8. Procalcitonin (PCT)

A procalcitonin test examines the amount of procalcitonin in your blood. A high amount might be a symptom of a dangerous bacterial illness, such as sepsis. Sepsis is the body’s extreme reaction to infection. Sepsis develops when an infection in one region of your body, such as your skin or urinary system, moves into your bloodstream. This test may also assist with treatment efficacy, monitor the infection of bacterial origin, etc.

The procalcitonin reference value for adults is less than 0.1 ng/mL. Infection may be indicated by levels more than 0.25 ng/mL.

9. Interleukin 10

Interleukin 10 is a type of cytokine that stops inflammation and is very important in preventing inflammatory and autoimmune diseases. When IL-10 levels are high, they can make it harder for the host to respond to microbial pathogenesis and stop tissue damage and changes in blood flow from healing. Its result are also obtained via blood testing. Serum IL-10 levels in healthy adults ranged from 4.8 to 9.8 pg/ml.

10. Interleukin-6

Interleukin-6 (IL-6) is a protein that is generated by several cell types. It helps control immunological responses, making the IL-6 test a possible indicator of immune system activity. Inflammation, infection, autoimmune disorders, cardiovascular disease, and some malignancies may all cause an increase in IL-6 levels. This blood test measures the blood’s IL-6 concentration. This test is not often requested, but it can be used if a person has been identified with or has signs and symptoms of one of the above conditions. Less than 17.4 pg/mL is the normal range for this blood test.

It is possible to learn a lot about your health by having blood tested from your body. In other cases, however, it fails to provide sufficient insight into your health status. It’s possible that your doctor may still need to do further tests after reviewing the results of your blood work. To learn what other tests are carried out, jump up to this article here.

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Being a Doctor by profession, Aimen is passionate about helping people get better health in their lives. Aimen enjoys her research on Prime With Time subjects and strives to create better awareness of the problems and changes related to women's health.

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