Health Library

Galactose-1-phosphate uridyltransferase is a blood test that measures the level of a substance called GALT, which helps break down milk sugars (lactose/galactose). Low levels of this substance cause a condition called galactosemia.

Galactosemia is a condition in which the body is unable to use () the simple sugar galactose.

Gallbladder disease includes inflammation, infection, stones, or blockage (obstruction) of the gallbladder.

Gallbladder radionuclide scan is a test that uses radioactive material to check gallbladder function or to look for signs of an infection or bile duct obstruction.

Laparoscopic gallbladder removal is surgery to remove the using a medical device called a laparoscope.

Open gallbladder removal is surgery to remove the gallbladder.

A gallium scan is a test that uses a radioactive material called gallium to look for swelling (inflammation), infection, or cancer in the body. It is a type of exam. See also:

Gallstones are hard, pebble-like deposits that form inside the gallbladder. Gallstones may be as small as a grain of sand or as large as a golf ball. See also:

Gamma-glutamyl transpeptidase (GGT) is a test to measure the amount of the GGT in the blood.

Ganglioneuroblastoma is an intermediate tumor arising from nerve tissue. An intermediate tumor is one that is between benign (slow-growing and unlikely to spread) and malignant (fast-growing, aggressive, and likely to spread).

Ganglioneuroma is a tumor of the peripheral nervous system.

Gangrene is the death of tissue in part of the body.

Gas, also called flatus or flatulence, is air in the intestine that is passed through the rectum. Air that is passed from the digestive tract through the mouth is called .

Gas gangrene is a potentially deadly form of tissue death (gangrene). See also:

This article discusses the harmful effects from swallowing gasoline or breathing in its fumes. This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the ...

Gastrectomy is surgery to remove part or all of the stomach. If only part of the stomach is removed, it is called partial gastrectomy If the whole stomach is removed, it is called total gastrectomy

Gastric bypass is surgery that is done to help you lose weight. After the surgery, you will not be able to eat as much as before, and your body will not absorb all the calories from the food you eat. See also:

Gastric cancer is cancer that starts in the stomach.

A gastric culture is a test to examine a child’s stomach contents for the bacteria that causes .

Gastric suction is a procedure to empty the contents of your stomach.

Gastric tissue is the removal of stomach tissue for examination. A culture is a laboratory test that examines the tissue sample for bacteria and other organisms that can cause disease.

Gastrin is the major hormone that regulates acid secretion in the stomach. It is produced by special cells in the stomach. Small amounts of gastrin may also be produced by the pancreas and possibly the intestines. When there is food in the stomach, gastrin is released into the blood. As stomach and ...

Gastritis occurs when the lining of the stomach becomes inflamed or swollen. Gastritis can last for only a short time (), or linger for months to years (chronic gastritis).

Acute gastritis is a sudden inflammation of the stomach lining.

Gastroesophageal reflux disease (GERD) is a condition in which the stomach contents (food or liquid) leak backwards from the stomach into the esophagus (the tube from the mouth to the stomach). This action can irritate the esophagus, causing heartburn and other symptoms.

Gastroesophageal reflux is a condition in which stomach contents leak backward from the stomach into the esophagus (the tube from the mouth to the stomach) after eating. This article discusses reflux in infants.

Gastrointestinal (GI) bleeding refers to any bleeding that starts in the gastrointestinal tract. Bleeding may come from any site along the GI tract, but is often divided into: Upper GI bleeding: The upper GI tract includes the esophagus (the tube from the mouth to the stomach), stomach, and first ...

A gastrointestinal fistula is an abnormal opening that allows the contents of the stomach or intestines to leak. If it leaks through to a part of the intestines, it is called an entero-enteral fistula. If it leaks to through to the skin, it is called an enterocutaneous fistula.

Gastrointestinal perforation is a hole that develops through the entire wall of the stomach, small intestine, large bowel, or gallbladder. This condition is a medical emergency.

Gastroparesis is a condition that reduces the ability of the stomach to empty its contents, but there is no blockage (obstruction).

Gastroschisis is a birth defect in which an infant’s intestines stick out of the body through a defect on one side of the umbilical cord. See also:

Gastroschisis repair is surgery to correct a birth defect that causes an opening in the skin and muscles covering the belly (abdominal wall). The opening allows intestines and sometimes other organs to bulge outside the belly. The surgeon places the organs back inside the belly and closes the belly ...

Gaucher disease is a rare genetic disorder in which a person lacks an enzyme called glucocerebrosidase.

Gender identity disorder is a conflict between a person’s actual physical gender and the gender that person identifies himself or herself as. For example, a person identified as a boy may actually feel and act like a girl. The person experiences significant discomfort with the biological sex ...

General anesthesia is a treatment that puts you into a deep sleep so you do not feel pain during surgery. When you receive these medications, you will not be aware of what is happening around you.

General paresis is an impairment of mental function caused by damage to the brain from untreated .

Generalized anxiety disorder (GAD) is a pattern of frequent, constant worry and over many different activities and events.

A generalized tonic-clonic seizure is a seizure involving the entire body. It is also called a grand mal seizure. Such seizures usually involve , violent , and . Generalized tonic-clonic seizures are the type of seizure that most people associate with the term “seizure,” convulsion, or ...

A gene is a short piece of DNA, which tells the body how to build a specific . There are approximately 30,000 genes in each cell of the human body. The combination of all genes makes up the blueprint for the human body and its functions. A person’s genetic makeup is called a genotype.

Genetically engineered foods have had foreign genes (genes from other plants or animals) inserted into their genetic codes. Genetic engineering can be done with plants, animals, or microorganisms. Historically, farmers bred plants and animals for thousands of years to produce the desired traits. ...

Genetics is the study of heredity, the process in which a parent passes certain onto their children. A person’s appearance — height, hair color, skin color, and eye color — are determined by genes. Other characteristics affected by heredity: Likelihood of getting certain ...

Genital herpes is a sexually transmitted viral infection affecting the skin or mucous membranes of the genitals.

A genital injury is an injury to the genitals or perineum, the area between the legs.

Sores or lesions on the female genitalia or in the vagina may have a number of possible causes.

A male genital sore is any sore or lesion that appears on the penis, scrotum, or male urethra.

Genital warts are soft, wart-like growths on the skin and mucus membranes of the genitals in men and women. Genital warts are a type of sexually transmitted infection (STI).

Geographic tongue is a map-like appearance of your tongue due to irregular patches on its surface.

Gestation is the period of time between conception and birth during which the fetus grows and develops inside the mother’s womb. Gestational age is the time measured from the first day of the woman’s last menstrual cycle to the current date. It is measured in weeks. A normal pregnancy ...

Gestational diabetes is high blood sugar () that starts or is first diagnosed during pregnancy.

Gestational trophoblastic disease (GTD) refers to a group of abnormalities in which tumors grow inside a woman’s uterus (womb). The abnormal cells start in the tissue that would normally become the placenta, the organ that develops during pregnancy to feed the fetus. A baby may or may not ...

A congenital pigmented or melanocytic nevus is a dark-colored, often hairy patch of skin that is present at birth. A giant congenital nevus is smaller in infants and children, but it usually continues to grow with the child. A giant pigmented nevus is larger than 8 inches once it stops growing.

Giardiasis is an infection of the small intestine caused by a microscopic organism (protozoa), Giardia lamblia.

Gigantism is abnormally large growth due to an excess of during childhood, before the bone growth plates have closed.

Gilbert’s disease is a common disorder passed down through families.It affects the way bilirubin is processed by the liver, and causes .

Gilles de la Tourette syndrome is a disorder of the nervous system that causes a person to make repeated and uncontrolled (involuntary) rapid movements and sounds (vocalizations) called tics. The disorder is commonly called Tourette syndrome. See also:

Gingivitis is inflammation of the gums (gingiva).

Gingivostomatitis is a viral or bacterial infection of the mouth and gums that leads to swelling and sores.

Glanzmann’s disease is a rare disorder of blood , which results in easy and .

Glaucoma refers to a group of eye conditions that lead to damage to the optic nerve, the nerve that carries visual information from the eye to the brain. In many cases, damage to the optic nerve is due to increased pressure in the eye, also known as intraocular pressure (IOP).

Glazes are products that add a shiny or glossy coating to a surface. Glaze poisoning occurs when someone swallows these substances. This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local ...

Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the tiny filters in the kidneys, called glomeruli, each minute. See also:

Glomerulonephritis is a type of in which the part of your kidneys that helps filter waste and fluids from the blood is damaged.

A glomus jugulare tumor is a tumor of a part of the temporal bone in the skull. This tumor can affect the ear, upper neck, base of the skull, and the surrounding blood vessels and nerves.

A glomus tympanum tumor is a tumor of the middle ear and bone behind the ear (mastoid).

Glossitis is a condition in which the tongue is swollen and changes color. Finger-like projections on the surface of the tongue (called papillae) are lost, causing the tongue to appear smooth. See also:

Glossopharyngeal neuralgia is a condition in which there are repeated episodes of severe pain in the tongue, throat, ear, and tonsils, which can last from a few seconds to a few minutes.

A glucagon test measures the amount of a hormone called glucagon in your blood. Glucagon is produced by cells in the pancreas. It helps control blood sugar levels.

Glucagonoma is a very rare of the islet cells of the pancreas, which leads to an excess of the hormone glucagon in the blood.

A blood glucose test measures the amount of a sugar, called glucose, in a sample of your blood. Glucose is a major source of energy for most cells of the body, including those in the brain. The carbohydrates you eat eventually end up as glucose in the blood. See also:

The glucose urine test measures the amount of sugar (glucose) in a urine sample. The presence of glucose in the urine is called glycosuria or glucosuria. See also:

The glucose tolerance test is a laboratory method to check how the body breaks down (metabolizes) sugar.

Glucose-6-phosphate dehydrogenase (G6PD) is a type of protein, called an , that helps red blood cells work properly. The G6PD test looks at the amount (activity) of this substance in a patient’s red blood cells.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a hereditary condition in which red blood cells break down when the body is exposed to certain drugs or the stress of infection.

Glucuronyl transferase is a liver . It changes into a form that can be removed through the . It also changes some hormones, medicines, and toxins into non-harmful products. If the body does not produce enough glucuronyl transferase, can occur.

A goiter is an enlargement of the thyroid gland. It is not cancer. See also: Colloid nodule goiter

Gonococcal arthritis is inflammation of a joint (usually just one) due to a gonorrhea infection. See also:

Gonorrhea is a common sexually transmitted disease (STD). See also: Disseminated gonococcemia

Goodpasture syndrome is a rare disease that can involve along with lung disease. However, some forms of the disease involve just the lung or kidney, not both.

Gout is a kind of arthritis that occurs when builds up in the joints. Acute gout is a painful condition that typically affects one joint. Chronic gout is repeated episodes of pain and inflammation, which may involve more than one joint.

Graft-versus-host disease (GVHD) is a complication that can occur after a stem cell or in which the newly transplanted material attacks the transplant recipient’s body. See also:

A gram stain of a skin lesion is a laboratory test that uses special stains to detect and identify bacteria in a sample from a skin sore. The gram stain method is one of the most commonly used techniques for the rapid diagnosis of bacterial infections.

Gram stain of tissue biopsy test involves using crystal violet stain to test a sample of tissue taken from a . The Gram stain method can be applied to almost any clinical specimen and is an excellent technique for making a general, basic identification of the type of bacteria present in the ...

A gram stain of urethral discharge is a test used to identify bacteria in fluid from the tube that drains urine from the bladder (urethra).

Granulocytes are a type of white blood cell that includes neutrophils, eosinophils, and basophils. They are called granulocytes because they are made of small granules, which contain important proteins. Granulocytes help the body fight bacterial infections. Persons who have lower numbers of ...

Granuloma annulare is a long-term () skin disease consisting of a rash with reddish bumps arranged in a circle or ring.

Granuloma inguinale is a sexually transmitted disease that is rarely seen in the United States.

Many people are allergic to pollens from grass and weeds. Such allergies usually occur in the late spring and summer. This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such ...

Many weed killers contain dangerous chemicals that are harmful if swallowed. This article discusses poisoning by swallowing weed killers containing a chemical called glyphosate. This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an ...

Graves disease is an that leads to overactivity of the thyroid gland ().

Gray syndrome is a dangerous condition that occurs in newborns (especially premature babies) who are given the drug chloramphenicol.

Grief is a reaction to a major loss. It is most often an unhappy and painful emotion.

A groin lump is localized swelling in the groin area (where the upper leg meets the lower abdomen). It may be firm or soft, tender or not painful at all.

Groin pain refers to discomfort in the area where the abdomen ends and the legs begin. This article focuses on groin pain in men.

Gross control means the ability to make large, general movements (such as waving an arm or lifting a leg). It requires proper coordination and function of muscle, bones, and nerves.

Group B streptococcal septicemia is a severe bacterial infection that affects . See also:

Growth hormone deficiency refers to abnormally short height in childhood due to the lack of growth hormone. See also:

The growth hormone (GH) stimulation test measures the level of (GH) in the blood after you receive medication that triggers the release of GH, such as arginine or GH-releasing hormone. The test measures the ability of the pituitary gland to release GH. See also:

The growth hormone suppression test determines whether growth hormone (GH) production is suppressed by high blood sugar.

The growth hormone test measures the amount of growth hormone in the blood.

Guillain-Barre syndrome is a serious disorder that occurs when the body’s defense (immune) system mistakenly attacks part of the nervous system. This leads to nerve inflammation that causes .

A gum is a surgery in which a small piece of gingival (gum) tissue is removed for examination.

A gumma is a soft, tumor-like growth of the tissues (granuloma).

Swollen gums are abnormally enlarged, bulging, or protruding.

Gynecomastia is the development of abnormally large breasts in males. It is related to the excess growth of breast tissue, rather than excess fat tissue.