Glossary

Health Terms beginning with "I"

Iatrogenic

Any condition, such as medication side effects, that has been caused by a physician or surgeon or by medical treatment or diagnostic procedures.

Ibandronate

A biphosphonate drug for the prevention and treatment of osteoporosis in postmenopausal women.

Ideology

Strongly held beliefs that guide a person's behavior.

IgA nephropathy

A kidney disorder caused by deposits of the protein immunoglobulin A (IgA) inside the glomeruli (filters) within the kidney. The IgA protein damages the glomeruli, leading to blood and protein in the urine, to swelling in the hands and feet and sometimes to kidney failure.

Imipramine

A type of antidepressant prescribed to treat cataplexy, hypnagogic hallucinations and sleep paralysis.

Immune globulin

A preparation of antibodies that can be given before or after a person is exposed to hepatitis A virus (HAV), offering short-term protection.

Immune system

The body's defense against invaders such as bacteria and viruses, the immune system continually knocks out invaders from our bodies. It uses a multipronged front of white blood cells, specific proteins called antibodies and other inflammatory proteins, including histamines, to attack invading substances.

Immunocompromised

A condition whereby the immune system has become weakened or compromised.

Immunomodulating agents

Drugs from this class often are used in autoimmune diseases like Sjögren's. These medications act very slowly, so they don't bring about immediate relief. As with corticosteroids (see separate entry), immunomodulating agents are generally used when there is internal organ involvement or vasculitis. Drugs from this class include hydroxychloroquine sulfate, an antimalarial drug; methotrexate, a folic acid inhibitor; and cyclophosphamide, a potent cytotoxic drug.

Immunosuppressants

These drugs are used to restrain the overly active immune system. This class includes methotrexate, azathioprine and cyclophosphamide, which can all be highly effective, but they also can prove extremely toxic and often have severe side effects. Close monitoring and lab tests (including liver-function tests) are advisable.

Immunosuppressive drugs

These drugs, which suppress the immune system, are often prescribed for scleroderma.

Immunotherapy

A series of injections containing doses of the substance that is believed to be causing allergic symptoms. Given over a period of time in increasing doses, these shots can help you build up a tolerance and become less sensitive to a particular substance.

Impaired glucose tolerance

Blood glucose (sugar) levels higher than normal but not high enough to be called diabetes. People with IGT may or may not develop diabetes.

Impedance analyzer

A portable instrument used to transmit a non-invasive, low frequency electrical current through electrodes placed on the patient's hand and foot to measure body fat composition. The change in voltage between the electrodes is measured, and the patient's body composition is calculated.

Impotence

A man's inability to achieve or sustain a penile erection.

Incisional biopsy

With a scalpel, your healthcare professional will take a wider and deeper sample of all your skin layers and then suture the wound with stitches. Incisional biopsies remove a portion of the tumor and excisional biopsies remove the entire tumor.

Incisional biopsy and excisional biopsy

A sample of all of the skin layers that is wider and deeper than the skin lesion. Incisional biopsies remove a portion of the tumor, and excisional biopsies remove the entire tumor.

Incontinence

Involuntary loss of urine that results in hygienic or social problems.

Indication

A specific disease or condition.

Individual coverage

Not to be confused with an individual policy; individual coverage is when only one individual—and not a spouse, family or children—is covered under a policy.

Individual policy

A single policy (covering an individual or a spouse and/or family) bought independent of a group.

Induction

A technique used to guide you into a hypnotic state.

Infarct

Area of dead or dying tissue, resulting from being cut off from the blood supply.

Infarction

A sudden loss of blood supply to tissue, causing the formation of an infarct.

Infertility

The lack of conception after one year of frequent unprotected intercourse. It affects approximately 15 percent of reproductive-aged couples. There can be multiple causes of infertility in men and women.

Inflammation

A typical reaction of tissues to injury or disease. It is marked by four signs: swelling, redness, heat and pain.

Inflammatory bowel diseases (IBD)

Long-lasting diseases that cause irritation and ulcers in the GI tract—the most common disorders are ulcerative colitis and Crohn's disease. Sometimes IBD is confused with irritible bowel syndrome (IBS).

Inflammatory carcinoma

The most aggressive breast cancer. It accounts for 1 to 4 percent of all cases. Skin over the breast appears acutely inflamed and swollen, because skin lymph vessels are blocked by cancer.

Influenza

An acute and highly contagious viral disease characterized by sudden onset, fever, weakness, severe aches and pains and progressive inflammation of the respiratory mucous membrane.

Informed consent

The process by which participants receive information about a clinical trial's risks and benefits and decide, based on that information, whether they wish to participate. Participants who opt to join the trial sign an informed consent document to signify their understanding of the risks and benefits.

Inhibited sexual desire disorder

Another name for hypoactive sexual desire disorder, which is persistent, recurrently reduced or absent sexual fantasies or thoughts and desire for sexual activity that cause distress or interpersonal difficulties.

Inhibitory neurotransmitters

Nerve-signaling chemicals that decrease activity in neurons.

Injectable chorionic gonadotropin

An injectable drug (APL, Pregnyl and Profasi) that produces effects similar to those of luteinizing hormone. It is often prescribed, in combination with urofollitropin and menotropins, for infertility that is not responsive to clomiphene.

Injectable human chorionic gonadotropin (HCG)

An injectable drug (APL, Pregnyl and Profasi) that produces effects similar to those of luteinizing hormone. It is often prescribed, in combination with gonadotropins, for infertility that is not responsive to clomiphene.

Insomnia

Trouble falling asleep, waking up in the middle of the night and having trouble getting back to sleep, or waking too early in the morning and staying awake.

Institutional Review Board (IRB)

Groups of scientists, doctors, nurses, clergy and consumers at health care facilities who review a specific protocol and decide whether or not it is scientifically sound, safe for participants and has potential benefit. Designed to protect participants who take part in studies, IRBs review and must approve the protocols for all clinical trials. They check to see that the study is well designed, does not involve undue risks and includes safeguards for participants.

Instruction directive

As part of a living will, a legal document that describes what type of care you would like if you are unable to decide for yourself in the future.

Insulin

A hormone that helps the body use glucose (sugar) for energy. The beta cells of the pancreas (in areas called the islets of Langerhans') make the insulin. When the body cannot make enough insulin, a person with diabetes must inject insulin made from other sources, i.e., beef, pork, human insulin (recombinant DNA origin or pork-derived, semisynthetic).

Insulin resistance

Many people with noninsulin-dependent diabetes produce enough insulin, but their bodies do not respond to the action of insulin. This may happen because the person is overweight and has too many fat cells, which do not respond well to insulin. Also, as people age, their body cells lose some of the ability to respond to insulin. Insulin resistance is also linked to high blood pressure and high levels of fat in the blood. Another kind of insulin resistance may occur in people who take insulin injections. They may have to take very high doses of insulin every day (200 units or more) to bring their blood glucose (sugar) down to the normal range. This is also called insulin insensitivity.

Insulin sensitizer

A new class of drugs that improves the body's ability to use insulin and reduce blood levels of insulin. Drugs in this class include metformin (Glucophage), pioglitazone (Actos) and rosiglitazone (Avandia). Since high levels of insulin stimulate testosterone production, these drugs may be effective in treating polycystic ovarian syndrome (PCOS) symptoms, including infertility.

Intensity

The level of exertion during exercise; a healthy person should aim for an intensity that increases their heart rate to between 70 percent and 85 percent of maximum.

Intensive management

A form of treatment for insulin-dependent diabetes in which the main objective is to keep blood glucose (sugar) levels as close to the normal range as possible. The treatment consists of three or more insulin injections a day or use of an insulin pump; four or more blood glucose tests a day; adjustment of insulin, food intake and activity levels based on blood glucose test results; dietary counseling; and management by a diabetes team.

Interdental cleaners

Special, small brushes, picks or sticks that are used to clean between the teeth.

Interferon

A naturally occurring antiviral substance that is used to treat hepatitis B or C virus. It can cause considerable side effects including flu-like symptoms. Hair loss, depression and tiredness also are experienced with long-term use.

Intermittent claudication

A circulatory condition that results in pain, cramping or numbness in one or both legs that starts when walking and stops when resting. The pain is caused by lack of oxygen in the leg muscles, usually because of a narrowing or blockage of arteries that carry blood and oxygen to the legs.

Interpersonal therapy

A type of psychotherapy that focuses on symptoms and current issues that may be causing problems. It typically concentrates on relationships.

Interstitial cystitis (IC)

A disorder that causes the bladder wall to become swollen and irritated, leading to scarring and stiffening of the bladder, decreased bladder capacity, and, in rare cases, ulcers in the bladder lining. IC is also known as painful bladder syndrome.

Interstitial nephritis

Inflammation of the kidney cells that are not part of the fluid-collecting units, a condition that can lead to acute renal failure or chronic renal failure.

Intimidate

To induce fear or a sense of inferiority. Abusers often use intimidation to gain control over their victims.

Intracerebral hemorrhage

When a vessel within the brain leaks blood into the brain.

Intractable epilepsy

Epilepsy in which a person continues to experience seizures even with the best available treatment.

Intracytoplasmic Sperm Injection (ICSI)

A form of artificial reproductive technology (ART) used when there are problems with the sperm or the couple is known to have a fertilization factor. With ICSI, an embryologist manipulates a single egg by directly injecting sperm into the cytoplasm of the egg. ICSI is highly specialized and not all centers have the equipment to perform it.

Intradermal tests

A diagnostic test for allergies that administers the allergen into the dermal layer of the skin rather than the surface layer.

Intramural fibroids

Fibroids confined within the uterine wall that may cause symptoms similar to fibroids in other parts of the uterus.

Intraocular pressure

The pressure of the fluid inside the eye.

Intrauterine device (IUD)

A long-acting device about the size of a quarter inserted into the uterus that helps to prevent pregnancy for five to ten years, depending on the type.

Intravenous

Administered by injection into the veins.

Intravenous pyelogram

A test in which a dye that is visible on an x-ray is injected into a vein. As the dye enters the kidneys, ureters and bladder, the x-ray is taken.

Intravenous pyelography

A test in which a dye that is visible on an x-ray is injected into a vein. As the dye enters the kidneys, ureters, and bladder, the x-ray is taken.

In utero

Describes a fetus while it is still developing in the uterus.

Invasive cervical cancer

The later stage of cervical cancer when the disease has spread deep into the cervix or other organs.

Invasive lobular carcinoma

Occurs at the ends of the ducts or in the lobules and accounts for less than 2 percent of cases.

Invasive Paget's disease

A rare breast cancer in the ducts beneath the nipple. It starts with an itchy, eczema-like rash around the nipple.

Investigator

A researcher.

In vitro fertilization (IVF)

Eggs are removed from the ovary via transvaginally guided ultrasound and aspiration after being stimulated with one or more fertility drugs to ensure that enough eggs are available for retrieval. Eggs and sperm are combined in a petri dish in a laboratory, which is placed in an incubator to encourage fertilization. When fertilization occurs, the resulting embryo is transferred back to the uterus during another procedure several days later.

Iridology

This diagnostic approach is based on the notion that each organ has a corresponding location within the eye's iris. Changes indicate a change in the organ function.

Iridotomy

A surgical procedure for angle-closure glaucoma using a laser to make a tiny hole in the iris to improve the flow of the aqueous humor to the drainage meshwork.

Iris

The colored part of the eye containing muscles that control opening and closing of the pupil.

Irritable bowel syndrome (IBS)

A common disorder of the intestines that leads to abdominal discomfort or pain and changes in bowel habits. The person with IBS seems to have a colon that is more sensitive and reactive than usual.

Ischemia

A loss of blood flow to tissue, caused by an obstruction of the blood vessel, usually in the form of plaque stenosis or a blood clot.

Ischemic stroke

Ischemia (loss of blood flow) in the tissues of the brain. Ischemic strokes account for the vast majority of strokes and are the result of blood clots blocking an artery, depriving a part of the brain of oxygen.

Isometrics

A form of exercise that increases muscular strength and endurance by putting pressure against stable resistance, often using your own body weight, such as push-ups.