Definitions

Here are some words that you may want to familiairize yourself with. Some have been taken from the Riley’s Children’s hospital website, and the others Aegis.com.  

These are from http://www.aegis.com/pubs/step/1993/step5104.html:

CD4 Percentage: In a healthy adult, helper T-cells account for between 32% and 68% of the total number of lymphocytes (which includes B-cells and other types of T-cells). The CD4 percentage is sometimes a more reliable measurement than the CD4 count because it tends to vary less between measurements. For example, one person’s CD4 count may vary between 160 and 240 over a period of several months while their CD4 percentage remains constant at, say, 15%. The reason for this is that the CD4 count isn’t actually a direct count of CD4 cells, but rather a calculation based on the results of three other tests (the CD4 percentage, the lymphocyte percentage, and the WBC count), each of which can vary slightly each time it’s measured. Occasionally the CD4 count may be relatively high while the CD4 percentage is low (less than 21%). In this situation, many healthcare providers would consider the immune system to be significantly impaired based on the CD4 percentage.

CD8 Count, CD8 Percentage, T-cell Ratio: CD8 cells, also called suppressor T-cells, play a role in fighting viral infections such as HIV. A healthy adult usually has between 150 and 1,000 CD8 cells per cubic millimeter. In contrast to CD4 cells, people with HIV often have elevated numbers of CD8 cells, the significance of which is not well understood. Lab reports may also list the T-cell ratio, which is the number of CD4 cells divided by the number of CD8 cells. Since the CD4 count is usually lower and the CD8 count higher than normal, the ratio is usually low in people with HIV. A normal T-cell ratio is usually between 0.9 and 6.0. The expected response to effective combination anti-HIV treatment is an increase in CD4 count, a decrease in CD8 count, and an increase in the T-cell ratio.

 This is from: http://www.thebody.com/content/art14477.html

 The ratio of CD4 cells to CD8 cells is often reported. This is calculated by dividing the CD4 value by the CD8 value. In healthy people, this ratio is between 0.9 and 1.9, meaning that there are about 1 to 2 CD4 cells for every CD8 cell. In people with HIV infection, this ratio drops dramatically, meaning that there are many times more CD8 cells than CD4 cells.

Because the CD4 counts are so variable, some health care providers prefer to look at the CD4 percentages. These percentages refer to total lymphocytes. If your test reports CD4% = 34%, that means that 34% of your lymphocytes were CD4 cells. This percentage is more stable than the number of CD4 cells. The normal range is between 20% and 40%. A CD4 percentage below 14% indicates serious immune damage. It is a sign of AIDS in people with HIV infection. A recent study showed that the CD4% is a predictor of HIV disease progression.


WHAT DO THE NUMBERS MEAN?

The meaning of CD8 cell counts is not clear, but it is being studied.

The CD4 cell count is a key measure of the health of the immune system. The lower the count, the greater damage HIV has done. Anyone who has less than 200 CD4 cells, or a CD4 percentage less than 14%, is considered to have AIDS according to the US Centers for Disease Control.

CD4 counts are used together with the viral load to estimate how long someone will stay healthy. See Fact Sheet 125 for more information on the viral load test.

 This is from: http://www.aids.org/factSheets/124-T-Cell-Tests.html

 Lymphocyte subsets – The category of lymphocyte subsets includes absolute counts and percentages of CD4 and CD8 cells as well as other parameters. Usually the number and percent of B cells is included and the number and percent of all lymphocytes (except those called “natural killer” or NK cells). Lymphocytes are broken down mainly into T and B cells. T cells are further divided into CD4(+) cells and CD8(+) cells. It is well known that HIV infection causes a slow, progressive decline in the number and percent of CD4(+) cells in most individuals. There are exceptions. Some individuals progress in their disease very rapidly and others don’t seem to progress much at all after more than 12 or 13 years of infection. Normal CD4 counts are 400-1500. The role of CD8 cells is less clearly understood. Early on in the epidemic, high CD8 cell counts caused inversion of the CD4:CD8 ratio and was thought to adversely affect illness. Now it is generally believed that elevated CD8 cell counts are advantageous in the HIV positive individual as it’s thought to indicate the body’s ability to keep HIV somewhat constrained. Normal CD8 cell counts in an HIV negative individual are 275-780. How CD8 cells are beneficial is still being investigated.

Amylase – an enzyme produced in the pancreas and salivary glands. Increases in the blood amylase may be an indication of pancreatitis.

Anemia – a decrease in the normal amount of red blood cells or hemoglobin. People with anemia may feel tired and fatigue easily.

Antibodies – a substance produced by the body to fight germs.

Antiretrovirals – the group of medications used to treat HIV/AIDS.

Burkitt’s lymphoma – a type of cancer found in the T and B cells of the immune system.

Candidiasis – yeast or fungal infection that can occur anywhere in the body. On the skin appears as a raised red rash; in the mouth looks like curdled milk.

Cat Scratch Disease – an illness caused by a cat scratch that results in swollen lymph glands, fever, and chills.

Coccidiodomycosis – an opportunistic infection of the lungs caused by a fungus that normally lives in the soil. Infection occurs when strong winds disrupt the soil and then the unseen spores are breathed into the lungs. This fungus is usually found in the southwestern United States (California, Arizona, and Texas). People with CD4 counts that are very low are more likely to develop infection with this fungus.

CD4 Cell (AKA T4 cell) – the part of the immune system that is attacked by HIV. People who are infected with HIV often have too few CD4 cells. CD4 cells play an important role in the way the immune system works.Also called T- helper cell, helper cell.

Compliance – following health care team’s instructions. It is extremely important to take each and every dose of medication as prescribed. Anyone taking less than 100% of their medications can develop resistance of the virus against that medication and possibly other medications as well.

Confidential – private. Confidential information can be shared ONLY WITH YOUR PERMISSION.

Cross Resistance – resistance to other medications from the same class of drugs.

Cryptococcosis – the most common cause of meningitis in people with AIDS. Usually found in people with extremely low CD4 counts. Symptoms include fever, headache, nausea, and vomiting. The infection can spread to other parts of the body. The yeast that causes this infection is found in the soil. People become infected when the soil is disturbed and the unseen spores are breathed into the lungs.

Cryptosporidium – an organism that enters the gut and causes diarrhea, pain, and weight loss.

Cytomegalovirus (CMV) – a virus that can affect many parts of the body and cause a variety of infections including pneumonia, diarrhea, and retinitis (eye infections).

Disclosure – giving information to others. Information regarding HIV status can ONLY be given with permission from the patient or guardian.

Discrimination – when someone is treated differently than others based on their HIV status.

Dysplasia (cervical) – changes from normal in the cells lining the cervix or uterus. These changes are not cancerous but can often lead to cancer.

Encephalitis – inflammation of the brain which can lead to seizures and death.

Encephalopathy – a condition that occurs in the brain that affects its development. In children, encephalopathy may result in developmental problems such as cerebral palsy.

Extrapulmonary – occurring outside the lungs.

Gammaglobulin – medication made from blood products that may be given after exposure to chicken pox or measles in an effort to avoid or lessen the disease.

Gastrointestinal Tract – the tube that extends from the mouth to the anus in which the movement of muscles and the release of hormones and enzymes digests food. Includes the mouth, esophagus, stomach, duodenum, small intestine, large intestine, rectum, and anus.

HAART – stands for highly activated antiretroviral therapy.

Helper Cell – a type of T cell that helps in the immune response. The HIV attacks these cells in the body.

Hepatitis – inflammation of the liver that can be caused by a viral infection or can be caused by other things including certain types of antiretroviral medication.

Heterosexual – a person sexually attracted to persons of the opposite sex.

Histoplasmosis – the most common fungal infection in the states of the Mississippi Valley (including Indiana). The yeast that causes this infection is found in the soil. People become infected when the soil is disturbed and the unseen spores are breathed into the lungs. It may spread outside the lungs to other parts of the body.

Homosexual – a person sexually attracted to persons of the same sex.

Immune System – the part of the body that fights germs and helps to prevent infection. It includes white blood cells and CD4 cells.

Kaposi’s Sarcoma – the most common form of cancer in people with HIV. Rarely occurs in children. This type of cancer affects the blood vessels. It appears as purple, pink, or red spots, patches, or raised areas on the skin. These “lesions” usually are found on the face, neck, chest, or back but can also occur in the internal organs.

Lipase – an enzyme in the body that measures the function of the pancreas. Elevations in lipase may indicate pancreatitis.

Lipodystrophy – a condition caused by antiretrovirals. It causes loss of fat tissue in certain areas of the body and fat accumulation in others.

Listeria – a bacteria usually found in contaminated food. Listeria can cause death in people with weakened immune systems.

Lymphoid Interstitial Pneumonitis (LIP) – a lung disease that may develop in children with HIV infection. This condition can cause permanent damage to the lungs. It is diagnosed by x-ray.

Lymphoma – a form of cancer that occurs in the T and B cells of the immune system. Not often seen in children but does sometimes occur.

Malabsorption – the process that occurs when food nutrients are not absorbed by the body.

Meningitis – inflammation in the brain caused by a virus or bacteria. Symptoms include high fever, headache, loss of appetite, and severe neck
pain. In infants, symptoms typically include irritability, fever, and poor feeding.

Metabolism – the process that occurs when the body generates energy. HIV can cause the body to work harder and to use more calories for energy. People with high viral loads usually have an increase in metabolism and usually have a hard time taking in enough calories to keep up with the body’s needs.

Monotherapy – treatment with only one medication. Rarely used in the treatment of HIV.

Mutate – to change in form. This happens when HIV changes itself to become resistant to medications.

Mycobacterium Avium Complex (MAC) – a condition caused by a type of bacteria that enters the body through the gut and other organs. Symptoms
include fever, weight loss, abdominal pain, loss of appetite, diarrhea, fatigue, and anemia.

Nutritionist – a person who specializes in diet and nutrition. Often called a dietitian.

Opportunistic Infections – an infection that occurs because of a weakened immune system. May be difficult to treat.

Pancreatitis – Inflammation of the pancreas. Some of the antiretroviral medications can have this condition as a side effect. This condition needs to be closely monitored.

PCR – a test that measures the amount of HIV in the body (also caused viral load).

Peripheral Neuropathy – a condition that affects the nerves of the body especially those of the legs and feet. Symptoms may include numbness, weakness, burning, or loss of reflexes. These symptoms should be immediately reported to the health care team.

Pneumocystis Carinii Pneumonia (PCP) – a lung infection that causes fever, dry cough, and difficulty breathing. This can be a very serious infection. In people with very low CD4 counts, medicine may be given to try and avoid this infection.

Progressive Multifocal Leukoencephalopathy (PML) – a serious life threatening opportunistic infection that affects the brain. It is rarely seen in children.

Prophylaxis – measures that are taken to prevent disease.

Resistance – in the treatment of HIV/AIDS, the virus may develop certain ways of avoiding the effects of medication and make the medication no longer work. The virus can then continue to multiply in the body.

Retrovirus – a type of virus. HIV is one.

Roadblocks – something that blocks or prevents you from a task such as taking medication.

Salmonella – a bacteria that can cause “food poisoning” and fever from contaminated foods.

Sexually Transmitted Diseases – an illness or infection transmitted during sexual contact. Includes HIV, chlamydia, genital herpes, genital warts, gonorrhea, syphilis, and yeast infections.

Shingles – an infection caused by the same virus that causes chicken pox (herpes zoster). After a case of chicken pox, the virus stays in the body and will later appear as shingles. This can occur when the immune system is weakened. Shingles is an extremely painful condition that causes inflammation of the nerves.

Superinfection – re-infection with a second strain or type of an illness.

Sushi – raw fish usually served with cold rice.

Thrush – yeast infection of the mouth. Usually looks like patches of white. Can be painful and does require treatment with a prescription medication.

Toxoplasmosis – an infection that enters the brain and causes flu-like symptoms such as fever, headache, seizures, and swollen lymph glands. Symptoms may last several weeks.

Tuberculosis – a highly contagious infection that attacks the lungs and other parts of the body. A skin test can be done to indicate infection.

Viral Load – the amount of HIV in the body.

Wasting – rapid weight loss.

CD4 Percentage: In a healthy adult, helper T-cells account for between 32% and 68% of the total number of lymphocytes (which includes B-cells and other types of T-cells). The CD4 percentage is sometimes a more reliable measurement than the CD4 count because it tends to vary less between measurements. For example, one person’s CD4 count may vary between 160 and 240 over a period of several months while their CD4 percentage remains constant at, say, 15%. The reason for this is that the CD4 count isn’t actually a direct count of CD4 cells, but rather a calculation based on the results of three other tests (the CD4 percentage, the lymphocyte percentage, and the WBC count), each of which can vary slightly each time it’s measured. Occasionally the CD4 count may be relatively high while the CD4 percentage is low (less than 21%). In this situation, many healthcare providers would consider the immune system to be significantly impaired based on the CD4 percentage.

CD8 Count, CD8 Percentage, T-cell Ratio: CD8 cells, also called suppressor T-cells, play a role in fighting viral infections such as HIV. A healthy adult usually has between 150 and 1,000 CD8 cells per cubic millimeter. In contrast to CD4 cells, people with HIV often have elevated numbers of CD8 cells, the significance of which is not well understood. Lab reports may also list the T-cell ratio, which is the number of CD4 cells divided by the number of CD8 cells. Since the CD4 count is usually lower and the CD8 count higher than normal, the ratio is usually low in people with HIV. A normal T-cell ratio is usually between 0.9 and 6.0. The expected response to effective combination anti-HIV treatment is an increase in CD4 count, a decrease in CD8 count, and an increase in the T-cell ratio.

 

This is from: http://www.thebody.com/content/art14477.html

 

The ratio of CD4 cells to CD8 cells is often reported. This is calculated by dividing the CD4 value by the CD8 value. In healthy people, this ratio is between 0.9 and 1.9, meaning that there are about 1 to 2 CD4 cells for every CD8 cell. In people with HIV infection, this ratio drops dramatically, meaning that there are many times more CD8 cells than CD4 cells.

Because the CD4 counts are so variable, some health care providers prefer to look at the CD4 percentages. These percentages refer to total lymphocytes. If your test reports CD4% = 34%, that means that 34% of your lymphocytes were CD4 cells. This percentage is more stable than the number of CD4 cells. The normal range is between 20% and 40%. A CD4 percentage below 14% indicates serious immune damage. It is a sign of AIDS in people with HIV infection. A recent study showed that the CD4% is a predictor of HIV disease progression.


WHAT DO THE NUMBERS MEAN?

The meaning of CD8 cell counts is not clear, but it is being studied.

The CD4 cell count is a key measure of the health of the immune system. The lower the count, the greater damage HIV has done. Anyone who has less than 200 CD4 cells, or a CD4 percentage less than 14%, is considered to have AIDS according to the US Centers for Disease Control.

CD4 counts are used together with the viral load to estimate how long someone will stay healthy. See Fact Sheet 125 for more information on the viral load test.

 

This is from: http://www.aids.org/factSheets/124-T-Cell-Tests.html

 

Lymphocyte subsets – The category of lymphocyte subsets includes absolute counts and percentages of CD4 and CD8 cells as well as other parameters. Usually the number and percent of B cells is included and the number and percent of all lymphocytes (except those called “natural killer” or NK cells). Lymphocytes are broken down mainly into T and B cells. T cells are further divided into CD4(+) cells and CD8(+) cells. It is well known that HIV infection causes a slow, progressive decline in the number and percent of CD4(+) cells in most individuals. There are exceptions. Some individuals progress in their disease very rapidly and others don’t seem to progress much at all after more than 12 or 13 years of infection. Normal CD4 counts are 400-1500. The role of CD8 cells is less clearly understood. Early on in the epidemic, high CD8 cell counts caused inversion of the CD4:CD8 ratio and was thought to adversely affect illness. Now it is generally believed that elevated CD8 cell counts are advantageous in the HIV positive individual as it’s thought to indicate the body’s ability to keep HIV somewhat constrained. Normal CD8 cell counts in an HIV negative individual are 275-780. How CD8 cells are beneficial is still being investigated.

The next set of terms are taken from http://rileychildrenshospital.com/parents-and-patients/living-with-hiv/hiv-appendixb.jsp

Amylase – an enzyme produced in the pancreas and salivary glands. Increases in the blood amylase may be an indication of pancreatitis.

Anemia – a decrease in the normal amount of red blood cells or hemoglobin. People with anemia may feel tired and fatigue easily.

Antibodies – a substance produced by the body to fight germs.

Antiretrovirals – the group of medications used to treat HIV/AIDS.

Burkitt’s lymphoma – a type of cancer found in the T and B cells of the immune system.

Candidiasis – yeast or fungal infection that can occur anywhere in the body. On the skin appears as a raised red rash; in the mouth looks like curdled milk.

Cat Scratch Disease – an illness caused by a cat scratch that results in swollen lymph glands, fever, and chills.

Coccidiodomycosis – an opportunistic infection of the lungs caused by a fungus that normally lives in the soil. Infection occurs when strong winds disrupt the soil and then the unseen spores are breathed into the lungs. This fungus is usually found in the southwestern United States (California, Arizona, and Texas). People with CD4 counts that are very low are more likely to develop infection with this fungus.

CD4 Cell (AKA T4 cell) – the part of the immune system that is attacked by HIV. People who are infected with HIV often have too few CD4 cells. CD4 cells play an important role in the way the immune system works.Also called T- helper cell, helper cell.

Compliance – following health care team’s instructions. It is extremely important to take each and every dose of medication as prescribed. Anyone taking less than 100% of their medications can develop resistance of the virus against that medication and possibly other medications as well.

Confidential – private. Confidential information can be shared ONLY WITH YOUR PERMISSION.

Cross Resistance – resistance to other medications from the same class of drugs.

Cryptococcosis – the most common cause of meningitis in people with AIDS. Usually found in people with extremely low CD4 counts. Symptoms include fever, headache, nausea, and vomiting. The infection can spread to other parts of the body. The yeast that causes this infection is found in the soil. People become infected when the soil is disturbed and the unseen spores are breathed into the lungs.

Cryptosporidium – an organism that enters the gut and causes diarrhea, pain, and weight loss.

Cytomegalovirus (CMV) – a virus that can affect many parts of the body and cause a variety of infections including pneumonia, diarrhea, and retinitis (eye infections).

Disclosure – giving information to others. Information regarding HIV status can ONLY be given with permission from the patient or guardian.

Discrimination – when someone is treated differently than others based on their HIV status.

Dysplasia (cervical) – changes from normal in the cells lining the cervix or uterus. These changes are not cancerous but can often lead to cancer.

Encephalitis – inflammation of the brain which can lead to seizures and death.

Encephalopathy – a condition that occurs in the brain that affects its development. In children, encephalopathy may result in developmental problems such as cerebral palsy.

Extrapulmonary – occurring outside the lungs.

Gammaglobulin – medication made from blood products that may be given after exposure to chicken pox or measles in an effort to avoid or lessen the disease.

Gastrointestinal Tract – the tube that extends from the mouth to the anus in which the movement of muscles and the release of hormones and enzymes digests food. Includes the mouth, esophagus, stomach, duodenum, small intestine, large intestine, rectum, and anus.

HAART – stands for highly activated antiretroviral therapy.

Helper Cell – a type of T cell that helps in the immune response. The HIV attacks these cells in the body.

Hepatitis – inflammation of the liver that can be caused by a viral infection or can be caused by other things including certain types of antiretroviral medication.

Heterosexual – a person sexually attracted to persons of the opposite sex.

Histoplasmosis – the most common fungal infection in the states of the Mississippi Valley (including Indiana). The yeast that causes this infection is found in the soil. People become infected when the soil is disturbed and the unseen spores are breathed into the lungs. It may spread outside the lungs to other parts of the body.

Homosexual – a person sexually attracted to persons of the same sex.

Immune System – the part of the body that fights germs and helps to prevent infection. It includes white blood cells and CD4 cells.

Kaposi’s Sarcoma – the most common form of cancer in people with HIV. Rarely occurs in children. This type of cancer affects the blood vessels. It appears as purple, pink, or red spots, patches, or raised areas on the skin. These “lesions” usually are found on the face, neck, chest, or back but can also occur in the internal organs.

Lipase – an enzyme in the body that measures the function of the pancreas. Elevations in lipase may indicate pancreatitis.

Lipodystrophy – a condition caused by antiretrovirals. It causes loss of fat tissue in certain areas of the body and fat accumulation in others.

Listeria – a bacteria usually found in contaminated food. Listeria can cause death in people with weakened immune systems.

Lymphoid Interstitial Pneumonitis (LIP) – a lung disease that may develop in children with HIV infection. This condition can cause permanent damage to the lungs. It is diagnosed by x-ray.

Lymphoma – a form of cancer that occurs in the T and B cells of the immune system. Not often seen in children but does sometimes occur.

Malabsorption – the process that occurs when food nutrients are not absorbed by the body.

Meningitis – inflammation in the brain caused by a virus or bacteria. Symptoms include high fever, headache, loss of appetite, and severe neck
pain. In infants, symptoms typically include irritability, fever, and poor feeding.

Metabolism – the process that occurs when the body generates energy. HIV can cause the body to work harder and to use more calories for energy. People with high viral loads usually have an increase in metabolism and usually have a hard time taking in enough calories to keep up with the body’s needs.

Monotherapy – treatment with only one medication. Rarely used in the treatment of HIV.

Mutate – to change in form. This happens when HIV changes itself to become resistant to medications.

Mycobacterium Avium Complex (MAC) – a condition caused by a type of bacteria that enters the body through the gut and other organs. Symptoms
include fever, weight loss, abdominal pain, loss of appetite, diarrhea, fatigue, and anemia.

Nutritionist – a person who specializes in diet and nutrition. Often called a dietitian.

Opportunistic Infections – an infection that occurs because of a weakened immune system. May be difficult to treat.

Pancreatitis – Inflammation of the pancreas. Some of the antiretroviral medications can have this condition as a side effect. This condition needs to be closely monitored.

PCR – a test that measures the amount of HIV in the body (also caused viral load).

Peripheral Neuropathy – a condition that affects the nerves of the body especially those of the legs and feet. Symptoms may include numbness, weakness, burning, or loss of reflexes. These symptoms should be immediately reported to the health care team.

Pneumocystis Carinii Pneumonia (PCP) – a lung infection that causes fever, dry cough, and difficulty breathing. This can be a very serious infection. In people with very low CD4 counts, medicine may be given to try and avoid this infection.

Progressive Multifocal Leukoencephalopathy (PML) – a serious life threatening opportunistic infection that affects the brain. It is rarely seen in children.

Prophylaxis – measures that are taken to prevent disease.

Resistance – in the treatment of HIV/AIDS, the virus may develop certain ways of avoiding the effects of medication and make the medication no longer work. The virus can then continue to multiply in the body.

Retrovirus – a type of virus. HIV is one.

Roadblocks – something that blocks or prevents you from a task such as taking medication.

Salmonella – a bacteria that can cause “food poisoning” and fever from contaminated foods.

Sexually Transmitted Diseases – an illness or infection transmitted during sexual contact. Includes HIV, chlamydia, genital herpes, genital warts, gonorrhea, syphilis, and yeast infections.

Shingles – an infection caused by the same virus that causes chicken pox (herpes zoster). After a case of chicken pox, the virus stays in the body and will later appear as shingles. This can occur when the immune system is weakened. Shingles is an extremely painful condition that causes inflammation of the nerves.

Superinfection – re-infection with a second strain or type of an illness.

Sushi – raw fish usually served with cold rice.

Thrush – yeast infection of the mouth. Usually looks like patches of white. Can be painful and does require treatment with a prescription medication.

Toxoplasmosis – an infection that enters the brain and causes flu-like symptoms such as fever, headache, seizures, and swollen lymph glands. Symptoms may last several weeks.

Tuberculosis – a highly contagious infection that attacks the lungs and other parts of the body. A skin test can be done to indicate infection.

Viral Load – the amount of HIV in the body.

Wasting – rapid weight loss.

 

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  1. Thank you for this great post and the definitions contained within it, it really helped me to learn a lot!

    Like

  2. My brother recommended I might like this blog.
    He was totally right. This publish truly made my day. You can not believe just how a lot time I had spent for this info!
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