ABOUT BLOOD TESTS

 What is a complete blood cell count (CBC)?

A CBC count is a measurement of size, number, and maturity of the different blood cells in the blood sample. A CBC can be used to find problems with either the production or destruction of blood cells. Variations from the normal number, size, or maturity of the blood cells can be used to mean there is an infection or disease process. Often with an infection, the number of white blood cells will be elevated. Many forms of cancer can affect the production of blood cells. For instance, an increase in the immature white blood cells in a CBC can be associated with leukemia. Blood diseases, such as anemia and sickle cell disease, will cause an abnormally low hemoglobin.

COMMON BLOOD TESTS

Overview:

Regular blood testing is one of the most important ways to keep track of your overall physical well-being.
Getting tested at routine intervals can allow you to see the way your body changes over time and empower you to make informed decisions about your health.

How often should I get routine blood work?

Your doctor will typically recommend that you get routine blood work at least once a year, around the same time as your yearly physical.

But this is the bare minimum. There are several major reasons you may want to get blood tests more often than that:

You’re experiencing unusual, persistent symptoms. These could include anything from fatigue to abnormal weight gain to new pain.

You want to optimize your health. Knowing levels of various blood components, such as HDL and LDL cholesterol, can allow you to tweak your diet or fitness plan to minimize unhealthy habits (that you may not even realize are unhealthy). This can also maximize the nutrients you put in your body and more.

You want to reduce your risk of disease or complications. Regular blood tests can catch the warning signs of almost any disease early. Many heart, lung, and kidney conditions can be diagnosed using blood tests.

Talk to your doctor first if you want to get certain tests more often than once a year.

What are some routine tests and others I should ask about?

Some of the most common routine tests are:

• complete blood count (CBC)
• chemistry (basic metabolic) panel
• thyroid panel
• nutrient tests for levels of vital nutrients, such as iron or B vitamins

Some other tests that you may want include:

• enzyme markers if you’re at risk for cancer or other conditions like liver cirrhosis, stroke, or celiac disease
• sexually transmitted disease (STD) tests if you have multiple sexual partners or a new partner

Why do some blood tests require fasting?

Everything you eat and drink contains vitamins, proteins, and other nutrients that can cause the related levels in your blood to temporarily spike or drop.

Fasting for 8–12 hours helps ensure that blood test results are free from these variables, making your test results as accurate as possible.

Some common tests that may require fasting include:

• cholesterol tests
• blood sugar tests
• liver function tests
• kidney function tests
• basic metabolic panel
• glucose tests

How long does it take to get results?

Results may take anywhere from a few hours to a few days to become available. Here’s an overview of how long some common tests may take:

• complete blood count (CBC): 24 hours
• basic metabolic panel: 24 hours
• complete metabolic panel: 24–72 hours
• lipid panel: 24 hours.

This can depend on the specific lab where you get tested or how many tests you get done at once. If you order multiple tests, you may not get the complete results until all of the tests are completed.

Sometimes a lab will only release results to your doctor, who reviews them and then releases them to you.

Who orders my blood tests?

Your doctor typically orders blood tests for you during a physical, checkup, or an appointment intended for a specific condition.

Blood testing is usually partially or fully covered by insurance. Ordering tests through your medical provider ensures that you’re not paying too much. Your doctor can also advise you on how to choose testing facilities that are reliable, well-managed, or convenient for you.

It’s possible to order your own blood tests without a doctor or even health insurance, but it’s not recommended. You may end up paying the full cost by not going through an insurance plan, which can be expensive.

And some blood testing facilities may not give you accurate results. One infamous case of this is Theranos, a Palo Alto, California, biotechnology firm shut down in 2018 when an investigation uncovered lies and fraud around the accuracy of its private blood testing technology.

BLOOD AND BLOOD COMPONENTS

What are the components of blood?

Plasma: The liquid component of the blood in which the following blood cells are suspended.

Red blood cells (erythrocytes): 

These carry oxygen from the lungs to the rest of the body.

Red blood cells at work: Hemoglobin is the protein inside red blood cells. It carries oxygen. Red blood cells also remove carbon dioxide from your body, bringing it to the lungs for you to exhale.

Red blood cells are made in the bone marrow. They typically live for about 120 days, and then they die.

White blood cells (leukocytes): 

These help fight infections and aid in the immune process. Types of white blood cells include:

• 

  Lymphocytes
• Monocytes
• Eosinophils
• Basophils
• Neutrophils

Platelets (thrombocytes): These help in blood clotting.

Platelets, or thrombocytes, are small, colorless cell fragments in our blood that form clots and stop or prevent bleeding. Platelets are made in our bone marrow, the sponge-like tissue inside our bones. Bone marrow contains stem cells that develop into red blood cells, white blood cells, and platelets.

Where are blood cells made?

Blood cells are made in the bone marrow. The bone marrow is the spongy material in the center of the bones that makes all types of blood cells.

There are other organs and systems in our bodies that help regulate blood cells. The lymph nodes, spleen, and liver help regulate the production, destruction, and function of cells. The production and development of new cells in the bone marrow is a process called hematopoiesis.

Blood cells formed in the bone marrow start out as stem cells. A stem cell (or hematopoietic stem cell) is the first phase of all blood cells. As the stem cell matures, several distinct cells evolve. These include red blood cells, white blood cells, and platelets. Immature blood cells are also called blasts. Some blasts stay in the marrow to mature. Others travel to other parts of the body to develop into mature, functioning blood cells.

What are the functions of blood cells?

The main job of red blood cells, or erythrocytes, is to carry oxygen from the lungs to the body tissues and carbon dioxide as a waste product, away from the tissues and back to the lungs. Hemoglobin (Hgb) is an important protein in the red blood cells that carries oxygen from the lungs to all parts of our body.

The main job of white blood cells, or leukocytes, is to fight infection. There are several types of white blood cells and each has its own role in fighting bacterial, viral, fungal, and parasitic infections. Types of white blood cells that are most important for helping protect the body from infection and foreign cells include the following:

• Neutrophils
• Eosinophils
• Lymphocytes
• Monocytes
• Basophils 

White blood cells help heal wounds not only by fighting infection but also by ingesting matter, such as dead cells, tissue debris, and old red blood cells.

Protect you from foreign bodies that enter the blood stream, such as allergens.

Are involved in the protection against mutated cells, such as cancer.

The main job of platelets, or thrombocytes, is blood clotting. Platelets are much smaller in size than the other blood cells. They group together to form clumps, or a plug, in the hole of a vessel to stop bleeding.

INTRODUCTION

What is Blood?

Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.

Functions of Blood:

• Supply of oxygen to tissues (bound to hemoglobin, which is carried in red cells)

• Supply of nutrients such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins (e.g., blood lipids))

• Removal of waste such as carbon dioxide, urea, and lactic acid

• Immunological functions, including circulation of white blood cells, and detection of foreign material by antibodies

• Coagulation, the response to a broken blood vessel, the conversion of blood from a liquid to a semisolid gel to stop bleeding

• Messenger functions, including the transport of hormones and the signaling of tissue damage
• Regulation of core body temperature

• Hydraulic functions.

Blood Components:

There are four basic components that comprise human blood: plasma, red blood cells, white blood cells and platelets.