All Tests

Gestational diabetes -- diabetes that develops during pregnancy -- is a relatively common complication of pregnancy, affecting about 6% of all pregnant women.

You may have a greater risk of developing gestational diabetes if you:

Are obese when you become pregnant
Have high blood pressure or other medical complications
Have given birth to a large (greater than 9 pounds) baby before
Have given birth to a baby that was stillborn or suffering from certain birth defects
Have had gestational diabetes in previous pregnancies
Have a family history of diabetes
Come from certain ethnic backgrounds, including African, Hispanic, Asian, Native American, or Pacific Islander
Are older than 30

Globulins are a group of proteins in your blood. They are made in your liver by your immune system. Globulins play an important role in liver function, blood clotting, and fighting infection. There are four main types of globulins. They are called alpha 1, alpha 2, beta, and gamma. Just as there are different types of globulins, there are different types of globulin tests. These include:

• Total protein test. This blood test measures two types of proteins: globulin and albumin. If protein levels are low, it can mean that you have liver or kidney disease.
• Serum protein electrophoresis. This blood test measures gamma globulins and other proteins in your blood. It can be used to diagnose a variety of conditions, including disorders of the immune system and a type of cancer called multiple myeloma.

Other names for globulin tests: Serum globulin electrophoresis, total protein

A glucose in urine test measures the amount of glucose in your urine. Glucose is a type of sugar. It is your body's main source of energy. A hormone called insulin helps move glucose from your bloodstream into your cells. If too much glucose gets into the blood, the extra glucose will be eliminated through your urine. A urine glucose test can be used to help determine if blood glucose levels are too high, which may be a sign of diabetes.

Other names: urine sugar test; urine glucose test; glucosuria test

Gallstones are hard pebble deposits that contain cholesterol and bilirubin. These are of the size of small grain or golf ball stones generally present at the end of your gallbladder. If left untreated, gallstones become bigger with time. Compared to big stones, small ones are more problematic as they travel from one place to another. 

Further, these tiny stones get blocked in arteries, causing blockage. Every year, millions of people experience this issue. This guide will explain common symptoms, risk factors, treatment, preventive measures, and more about gallstones. We will also discuss top foods that you must avoid in such a condition. So, here we go.

An Introduction to Cholelithiasis

Gallstones, or cholelithiasis, are tiny bile deposits present in your gallbladder. These stones may sometimes cause blockage and swelling, causing severe health issues. If not treated timely, these can lead to complications like cancer and jaundice. Generally, gallstones are of two types. These include: 

• Cholesterol stones 

• Pigment stones

Cholesterol stones have a yellow or green tint. Whereas, some pigment stones made up of bilirubin are usually brown. In some cases, patients may have both of these stones at one time. 

Gynecomastia is enlargement of the glandular tissue of the male breast.
The condition may occur during infancy and puberty in normally-developing boys.
Gynecomastia results from an imbalance in the hormonal environment in the body, with a relative excess of estrogens (female hormones) when compared to androgens (male hormones).

Inflammation of the soft tissue (gingiva) and abnormal loss of bone that surrounds the teeth and holds them in place. Gum disease is caused by toxins secreted by bacteria in "plaque" that accumulate over time along the gum line. This plaque is a mixture of food, saliva, and bacteria. Early symptoms of gum disease include gum bleeding without pain. Pain is a symptom of more advanced gum disease as the loss of bone around the teeth leads to the formation of gum pockets. Bacteria in these pockets cause gum infection, swelling, pain, and further bone destruction. Advanced gum disease can cause loss of otherwise healthy teeth.

Gout is a form of acute arthritis that causes severe pain and swelling in the joints. It most commonly affects the big toe, but may also affect the heel, ankle, hand, wrist, or elbow. It affects the spine often enough to be a factor in back pain. Gout usually comes on suddenly, goes away after 5-10 days, and can keep recurring. Gout is different from other forms of arthritis because it occurs when there are high levels of uric acid circulating in the blood, which can cause urate crystals to settle in the tissues of the joints.

A noncancerous enlargement of the thyroid gland. With a goiter, the levels of thyroid hormones may be normal (euthyroid), elevated (hyperthyroidism), or decreased (hypothyroidism).

Gluten is a protein found primarily in wheat, barley and rye. If a person has a gluten intolerance, this protein can cause digestive problems such as gassiness, abdominal pain or diarrhea. Gluten intolerance is sometimes confused with Celiac disease, or thought of as a food allergy.

A common eye condition in which the fluid pressure inside the eye rises to a level higher than healthy for that eye. If untreated, it may damage the optic nerve, causing the loss of vision or even blindness.

The elderly, African-Americans, and people with family histories of the disease are at greatest risk. There are no symptoms in the early stage of glaucoma. Glaucoma is often called "the sneak thief of sight." Often, by the time the patient notices vision loss, glaucoma can only be halted, not reversed.

There are several different types of glaucoma, including open-angle glaucoma and acute angle-closure glaucoma. Open-angle glaucoma is the common adult-onset type of glaucoma. Acute angle-closure glaucoma is a less common form of glaucoma that can rapidly impair vision.

The treatment of glaucoma may include medication, surgery, or laser surgery. Eyedrops or pills alone can usually control glaucoma, although they cannot cure it. Some drugs are designed to reduce pressure by slowing the flow of fluid into the eye, while others help to improve fluid drainage. Surgery to help fluid escape from the eye, and laser surgery is now often used for the same purpose. In laser surgery for glaucoma, a laser beam of light is focused on the part of the anterior chamber where the fluid leaves the eye. This results in a series of small changes, making it easier for fluid to exit. Over time, the effect of laser surgery may wear off.

Gingivitis: Gum disease with inflammation of the gums. On inspection, the gums will appear red and puffy, and will usually bleed during tooth-brushing or dental examination. Treatment is by improved cleaning, with more-frequent and longer brushing and flossing, and/or the use of electronic tooth-cleaning equipment. Antiseptic mouthwashes may also be recommended. See also acute membranous gingivitis

Gastritis is inflammation of the lining of the stomach.[1] It may occur as a short episode or may be of a long duration.[1] There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain.[1] Other possible symptoms include nausea and vomiting, bloating, loss of appetite and heartburn.[1][2] Complications may include bleeding, stomach ulcers, and stomach tumors.[1] When due to autoimmune problems, low red blood cells due to not enough vitamin B12 may occur, a condition known as pernicious anemia.[3]

Common causes include infection with Helicobacter pylori and use of NSAIDs.[1] Less common causes include alcohol, smoking, cocaine, severe illness, autoimmune problems, radiation therapy and Crohn's disease.[1][6] Endoscopy, a type of X-ray known as an upper gastrointestinal series, blood tests, and stool tests may help with diagnosis.[1] The symptoms of gastritis may be a presentation of a myocardial infarction.[2] Other conditions with similar symptoms include inflammation of the pancreas, gallbladder problems, and peptic ulcer disease.[2]

Gas – Everyone has it, no matter how small or big we are. We eliminate it by burping or passing it on the other end.  Passing gas 14 to 23 times a day is normal for both adults and children. Even though it is entirely natural and unavoidable, it can be embarrassing.  Furthermore, when gas does not pass easily, pain often results…upset stomach, bloating and cramping.

Children are particularly susceptible to discomfort caused by gas as their delicate digestive systems develop and learn to move gas through their digestive tracts effectively.  Understanding causes, ways to reduce symptoms and treatment will help most find relief. If a child has persistently painful or extreme gassiness, it should be brought to the attention of your doctor, as it could be the sign of a more serious medical problem.

Gastritis commonly refers to inflammation of the lining of the stomach, but the term is often used to cover a variety of symptoms resulting from stomach lining inflammation and symptoms of burning or discomfort. True gastritis comes in several forms and is diagnosed using a combination of tests. In the 1990s, scientists discovered that the main cause of true gastritis is infection from a bacterium called Helicobacter pylori (H. pylori).

Gastroenteritis is an inflammation of the digestive tract, particularly the stomach, and large and small intestines. Viral and bacterial gastroenteritis are intestinal infections associated with symptoms of diarrhea , abdominal cramps, nausea , and vomiting .

Gastroenteritis is an uncomfortable and inconvenient ailment, but is rarely life-threatening in the United States and other developed nations. Viral gastroenteritis is frequently referred to as the stomach or intestinal flu, although the influenza virus is not associated with this illness.

Gastroesophageal reflux disease, commonly referred to as GERD or acid reflux, is a condition in which the liquid content of the stomach regurgitates (backs up or refluxes) into the esophagus. The liquid can inflame and damage the lining (esophagitis) although visible signs of inflammation occur in a minority of patients. The regurgitated liquid usually contains acid and pepsin that are produced by the stomach. (Pepsin is an enzyme that begins the digestion of proteins in the stomach.) The refluxed liquid also may contain bile that has backed-up into the stomach from the duodenum. The first part of the small intestine attached to the stomach. Acid is believed to be the most injurious component of the refluxed liquid. Pepsin and bile also may injure the esophagus, but their role in the production of esophageal inflammation and damage is not as clear as the role of acid.

GERD is a chronic condition. Once it begins, it usually is life-long. If there is injury to the lining of the esophagus (esophagitis), this also is a chronic condition. Moreover, after the esophagus has healed with treatment and treatment is stopped, the injury will return in most patients within a few months. Once treatment for GERD is begun it will need to be continued indefinitely although. However, some patients with intermittent symptoms and no esophagitis can be treated only during symptomatic periods.

It's normal to feel anxious from time to time, especially if your life is stressful. However, excessive, ongoing anxiety and worry that are difficult to control and interfere with day-to-day activities may be a sign of generalized anxiety disorder.

It's possible to develop generalized anxiety disorder as a child or an adult. Generalized anxiety disorder has symptoms that are similar to panic disorder, obsessive-compulsive disorder and other types of anxiety, but they're all different conditions.

Living with generalized anxiety disorder can be a long-term challenge. In many cases, it occurs along with other anxiety or mood disorders. In most cases, generalized anxiety disorder improves with psychotherapy or medications. Making lifestyle changes, learning coping skills and using relaxation techniques also can help.

Glioblastoma is an aggressive type of cancer that can occur in the brain or spinal cord. Glioblastoma forms from cells called astrocytes that support nerve cells.

Glioblastoma can occur at any age, but tends to occur more often in older adults. It can cause worsening headaches, nausea, vomiting and seizures.

Glioblastoma, also known as glioblastoma multiforme, can be very difficult to treat and a cure is often not possible. Treatments may slow progression of the cancer and reduce signs and symptoms.

Glioma is a type of tumor that occurs in the brain and spinal cord. Gliomas begin in the gluey supportive cells (glial cells) that surround nerve cells and help them function.

Three types of glial cells can produce tumors. Gliomas are classified according to the type of glial cell involved in the tumor.

Types of glioma include:

Astrocytomas, including astrocytoma, anaplastic astrocytoma and glioblastoma

Ependymomas, including anaplastic ependymoma, myxopapillary ependymoma and subependymoma

Oligodendrogliomas, including oligodendroglioma, anaplastic oligodendroglioma and anaplastic oligoastrocytoma

Gliomas can affect your brain function and be life-threatening depending on their location and rate of growth.

Gliomas are one of the most common types of primary brain tumors.

The type of glioma you have helps determine your treatment and your prognosis. In general, glioma treatment options include surgery, radiation therapy, chemotherapy, targeted therapy and experimental clinical trials.

Glomerulonephritis (gloe-mer-u-low-nuh-FRY-tis) is inflammation of the tiny filters in your kidneys (glomeruli). Glomeruli remove excess fluid, electrolytes and waste from your bloodstream and pass them into your urine. Glomerulonephritis can come on suddenly (acute) or gradually (chronic).

Glomerulonephritis occurs on its own or as part of another disease, such as lupus or diabetes. Severe or prolonged inflammation associated with glomerulonephritis can damage your kidneys. Treatment depends on the type of glomerulonephritis you have.

Golfers elbow or medial epicondylitis is an overuse injury similar to tennis elbow (on the outside of the arm) but causing pain on the inside of the elbow instead. It is sometimes known as throwers elbow or little league elbow. We explain the symptoms, causes and treatment to return you back to full fitness in the shortest time.

A grand mal seizure causes a loss of consciousness and violent muscle contractions. It's the type of seizure most people picture when they think about seizures.

A grand mal seizure — also known as a generalized tonic-clonic seizure — is caused by abnormal electrical activity throughout the brain. Usually, a grand mal seizure is caused by epilepsy. But sometimes, this type of seizure can be triggered by other health problems, such as extremely low blood sugar, a high fever or a stroke.

Many people who have a grand mal seizure never have another one and don't need treatment. But someone who has recurrent seizures may need treatment with daily anti-seizure medications to control and prevent future grand mal seizures.

Granuloma annulare (gran-u-LOW-muh an-u-LAR-e) is a skin condition that most commonly consists of raised, reddish or skin-colored bumps (lesions) that form ring patterns — usually on your hands and feet.

No one knows exactly what causes granuloma annulare. But it may be triggered by minor skin injuries and certain medications. Some types of granuloma annulare affect adults, and others typically affect children.

In most cases, granuloma annulare isn't itchy or painful, so no treatment is necessary. The lesions usually disappear on their own within two years. If you're bothered by how your skin looks, your doctor can prescribe medications that will speed the disappearance of the lesions.

Greenstick fractures occur when the force applied to a bone results in bending of the bone such that the structural integrity of the convex surface is overcome. The fact that the integrity of the cortex has been overcome results in fracture of the convex surface. However, the bending force applied does not break the bone completely and the concave surface of the bent bone remains intact.

This can occur following an angulated longitudinal force applied down the bone (e.g. an indirect trauma following a fall on an outstretched arm), or after a force applied perpendicular to the bone (e.g. a direct blow).

This fracture is very different, and much less common, than the torus fracture that results in buckling of the cortex on the concave side of the bend and an intact concave surface.

Growing pains are often described as an ache or throb in the legs — often in the front of the thighs, the calves or behind the knees. Growing pains tend to affect both legs and occur at night, and may even wake a child from sleep.

Although these pains are called growing pains, there's no evidence that growth hurts. Growing pains may be linked to a lowered pain threshold or, in some cases, to psychological issues.

There's no specific treatment for growing pains. You can make your child more comfortable by putting a warm heating pad on the sore muscles and massaging them.

Galactorrhea (guh-lack-toe-REE-uh) is a milky nipple discharge unrelated to the normal milk production of breast-feeding. Galactorrhea itself isn't a disease, but it could be a sign of an underlying problem. It usually occurs in women, even those who have never had children or after menopause. But galactorrhea can happen in men and even in infants.

Excessive breast stimulation, medication side effects or disorders of the pituitary gland all may contribute to galactorrhea. Often, galactorrhea results from increased levels of prolactin, the hormone that stimulates milk production.

Gallbladder cancer is cancer that begins in the gallbladder.

Your gallbladder is a small, pear-shaped organ on the right side of your abdomen, just beneath your liver. The gallbladder stores bile, a digestive fluid produced by your liver.

Gallbladder cancer is uncommon. When gallbladder cancer is discovered at its earliest stages, the chance for a cure is very good. But most gallbladder cancers are discovered at a late stage, when the prognosis is often very poor.

Gallbladder cancer is difficult to diagnose because it often causes no specific signs or symptoms. Also, the relatively hidden nature of the gallbladder makes it easier for gallbladder cancer to grow without being detected.

Ganglion cysts are noncancerous lumps that most commonly develop along the tendons or joints of your wrists or hands. They also may occur in the ankles and feet. Ganglion cysts are typically round or oval and are filled with a jellylike fluid.

Small ganglion cysts can be pea-sized, while larger ones can be around an inch (2.5 centimeters) in diameter. Ganglion cysts can be painful if they press on a nearby nerve. Their location can sometimes interfere with joint movement.

If your ganglion cyst is causing you problems, your doctor may suggest trying to drain the cyst with a needle. Removing the cyst surgically also is an option. But if you have no symptoms, no treatment is necessary. In many cases, the cysts go away on their own.

Gangrene is a condition that occurs when body tissue dies. It is caused by a loss of blood supply due to an underlying illness, injury, and/or infection. Fingers, toes, and limbs are most often affected, but gangrene can also occur inside the body, damaging organs and muscles. There are different types of gangrene and all require immediate medical attention.

Gastrointestinal (GI) bleeding is a symptom of a disorder in your digestive tract. The blood often appears in stool or vomit but isn't always visible, though it may cause the stool to look black or tarry. The level of bleeding can range from mild to severe and life-threatening.

Bleeding in the stomach or colon can usually be easily identified, but finding the cause of bleeding that occurs in the small intestine can be difficult. But sophisticated imaging technology can usually locate the problem, and minimally invasive procedures often can fix it.

Gastroparesis means weakness of the muscles of the stomach. Gastroparesis results in poor grinding of food in the stomach into small particles and slow emptying of food from the stomach into the small intestine.

The stomach is a hollow organ composed primarily of muscle. Solid food that has been swallowed is stored in the stomach while it is ground into tiny pieces by the constant churning generated by rhythmic contractions of the stomach's muscles. Smaller particles are digested better in the small intestine than larger particles, and only food that has been ground into small particles is emptied from the stomach and well digested. Liquid food does not require grinding.

The ground solid and liquid food is emptied from the stomach into the small intestine slowly in a metered fashion. The metering process allows the emptied food to be well-mixed with the digestive juices of the small intestine, pancreas, and liver (bile) and to be absorbed well from the intestine. The metering process by which solid and liquid foods are emptied from the stomach is a result of a combination of relaxation of the muscle in parts of the stomach designed to accommodate (store) food, and the pressure generated by the muscle in other parts of the stomach that pushes the food into the small intestine. (Thus, the stomach can store and empty food at the same time.) The metering also is controlled by the opening and closing of the pylorus, the muscular opening of the stomach into the small intestine.

When the contractions of the stomach's muscles are weakened, food is not thoroughly ground and does not empty into the intestine normally. Since the muscular actions whereby solid food and liquid food are emptied from the stomach are slightly different, the emptying of solids and liquids follows different time courses, and there may be slow emptying of solid food (most common), solid and liquid food (less common), or liquid food alone (least common).

Gaucher (go-SHAY) disease is the result of a buildup of certain fatty substances in certain organs, particularly your spleen and liver. This causes these organs to enlarge and can affect their function.

The fatty substances also can build up in bone tissue, weakening the bone and increasing the risk of fractures. If the bone marrow is affected, it can interfere with your blood's ability to clot.

An enzyme that breaks down these fatty substances doesn't work properly in people with Gaucher disease. Treatment often includes enzyme replacement therapy.

An inherited disorder, Gaucher disease is most common in Jewish people of Eastern and Central European descent (Ashkenazi). Symptoms can appear at any age.

Genital herpes is a common sexually transmitted infection caused by the herpes simplex virus (HSV). Sexual contact is the primary way that the virus spreads. After the initial infection, the virus lies dormant in your body and can reactivate several times a year.

Genital herpes can cause pain, itching and sores in your genital area. But you may have no signs or symptoms of genital herpes. If infected, you can be contagious even if you have no visible sores.

There's no cure for genital herpes, but medications can ease symptoms and reduce the risk of infecting others. Condoms also can help prevent the spread of a genital herpes infection.

Geographic tongue is the name of a condition that gets its name from its map-like appearance on the upper surface and sides of the tongue. It may occur in other areas of your mouth, as well.

You'll be relieved to know that geographic tongue is a harmless, benign condition that isn't linked to any infection or cancer. Two other names for geographic tongue are benign migratory glossitis and erythema migrans.

Affecting about 1% to 3% of people, geographic tongue can show up at any age. However, it tends to affect middle-aged or older adults more often. It appears to be more common in women than in men.

Germ cell tumors are growths that form from reproductive cells. Tumors may be cancerous or noncancerous. Most germ cell tumors that are cancerous occur as cancer of the testicles (testicular cancer) or cancer of the ovaries (ovarian cancer).

Some germ cell tumors occur in other areas of the body, such as the abdomen, brain and chest, though it's not clear why. Germ cell tumors that occur in places other than the testicles and ovaries (extragonadal germ cell tumors) are very rare.

Germ cell tumors tend to respond to treatment and many can be cured, even when diagnosed at a late stage.

Giardiasis is an infection in your small intestine. It’s caused by a microscopic parasite called Giardia lamblia. Giardiasis spreads through contact with infected people. And you can get giardiasis by eating contaminated food or drinking contaminated water. Pet dogs and cats also frequently contract giardia.

This condition can be found all over the world, according to the Centers for Disease Control and Prevention (CDC). However, it’s more common in overcrowded developing countries that lack sanitary conditions and water quality control.

Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme involved in energy production. It is found in all cells, including red blood cells (RBCs) and helps protect them from certain toxic by-products of cellular metabolism. A deficiency in G6PD causes RBCs to become more vulnerable to breaking apart (hemolysis) under certain conditions. This test measures the amount of G6PD in RBCs to help diagnose a deficiency.

G6PD deficiency is a genetic disorder. When individuals who have inherited this condition are exposed to a trigger such as stress, an infection, certain drugs or other substance(s), significant changes occur in the structure of the outer layer (cell membrane) of their red blood cells. Hemoglobin, the life-sustaining, oxygen-transporting protein within RBCs, forms deposits (precipitates) called Heinz bodies. Some individuals may experience these reactions when exposed to fava beans, a condition called "favism." With these changes, RBCs can break apart more readily, causing a decrease in the number of RBCs. When the body cannot produce sufficient RBCs to replace those destroyed, hemolytic anemia results and the individual may develop jaundice, weakness, fatigue, and/or shortness of breath.

G6PD deficiency is the most common enzyme deficiency in the world, affecting more than 400 million people. It may be seen in up to 10% of African-American males and 20% of African males. It is also commonly found in people from the Mediterranean and Southeast Asia.

G6PD deficiency is inherited, passed from parent to child, due to mutations or changes in the G6PD gene that cause decreased enzyme activity. There are over 440 variants of G6PD deficiency. The G6PD gene is located on the sex-linked X chromosome. Since men have one X and one Y sex chromosome, their single X chromosome carries the G6PD gene. This may result in a G6PD deficiency if a male inherits the single X chromosome with an altered gene.

Since women have two X sex chromosomes, they inherit two copies of the G6PD gene. Women with only one mutated gene (heterozygous) produce enough G6PD that they usually do not experience any symptoms (i.e., asymptomatic), but under situations of stress, they may demonstrate a mild form of the deficiency. In addition, a mother may pass the single mutated gene to any male children. Rarely do women have two mutated gene copies (homozygous), which could result in G6PD deficiency.

Galactose is a sugar that is part of the lactose found in milk and milk products. A galactosemia test is a blood or urine test that checks for enzymes that are needed to change galactose into glucose, a sugar that your body uses for energy. A person with galactosemia doesn't have one of these enzymes, so high levels of galactose build up in the blood or urine.

When galactose builds up in a baby's blood, it can cause liver damage, problems with eating, and intellectual disabilities. The damage caused by galactosemia can begin within weeks after the baby has started drinking breast milk or formula. Babies with galactosemia need foods low in galactose in order to gain weight and to prevent brain damage, liver problems, infection, and cataracts.

Galactosemia is a rare disease that is passed from parents to children (inherited genetic disorder). A galactosemia test is usually done to determine whether a newborn has the disease. In a family with a member who has galactosemia, a genetic test can be done on adults to find out whether they have an increased chance of having a child with the disease.

A ganglioside is a molecule of a glycosphingolipid with one other sialic salts  sialic acids (e.g. n-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate sialic acid, makes the head groups of gangliosides anionic at pH 7, which distinguishes them from globosides.

The name ganglioside was first applied by the German scientist Ernst Klenk in 1942 to lipids newly isolated from ganglion cells of the brain. More than 60 gangliosides are known, which differ from each other mainly in the position and number of NANA residues. It is a component of the cell plasma membrane that modulates cell signal transduction events, and appears to concentrate in lipid rafts

Gastrin is a hormone produced by "G-cells" in the part of the stomach called the antrum. It regulates the production of acid in the body of the stomach during the digestive process. This test measures the amount of gastrin in the blood to help evaluate an individual with recurrent peptic ulcers and/or other serious abdominal symptoms.

When food is eaten, the antrum of the stomach becomes distended and the presence of food stimulates the release of gastrin. Gastrin in turn stimulates parietal cells to produce gastric acid. Acidity helps to digest food and the rise in acidity eventually suppresses gastrin release. This feedback system normally results in low concentrations of gastrin in the blood, especially in the fasting state. Rare conditions such as G-cell hyperplasia and gastrinomas, including Zollinger-Ellison (ZE) syndrome, can cause an overproduction of gastrin and gastric acid. This can lead to aggressive peptic ulcers that can be difficult to treat.

Gastrinomas are gastrin-producing tumors. ZE syndrome is a condition caused by the presence of one or more gastrinomas and is characterized by high gastrin levels, greatly increased gastric acid production, and by peptic ulcers. Gastrinomas usually form in the pancreas, even though the endocrine cells of the pancreas do not normally make gastrin. More than half of them are malignant, causing cancer that can spread to other parts of the body, such as the liver. Even tiny tumors can produce large quantities of gastrin.

GCT test is used to help diagnose gestational diabetes and type 2 diabetes. A glucose tolerance test measures how well your body’s cells are able to absorb glucose, or sugar, after you ingest a given amount of sugar.

Gamma-glutamyl transferase (GGT) is an enzyme that is found in many organs throughout the body, with the highest concentrations found in the liver. GGT is elevated in the blood in most diseases that cause damage to the liver or bile ducts. This test measures the level of GGT in a blood sample.

Normally, GGT is present in low levels, but when the liver is injured, the GGT level can rise. GGT is usually the first liver enzyme to rise in the blood when any of the bile ducts that carry bile from the liver to the intestines become obstructed, for example, by tumors or stones. This makes it the most sensitive liver enzyme test for detecting bile duct problems.

However, the GGT test is not very specific and is not useful in differentiating between various causes of liver damage because it can be elevated with many types of liver diseases, such as liver cancer and viral hepatitis, as well as other non-hepatic conditions, such as acute coronary syndrome. For this reason, the GGT test is not recommended for routine use by itself. However, it can be useful in conjunction with other tests and in determining the cause of a high alkaline phosphatase (ALP) level, another enzyme found in the liver.

Both GGT and ALP are increased in liver diseases, but only ALP will be increased with diseases affecting bone tissue. Therefore, GGT can be used as a follow up to an elevated ALP to help determine if the high ALP result is due to liver or bone disease.

GGT levels are sometimes increased with consumption of even small amounts of alcohol. Higher levels are found more commonly in chronic heavy drinkers than in people who consume less than 2 to 3 drinks per day or who only drink heavily on occasion (binge drinkers). The GGT test may be used in evaluating someone for acute or chronic alcohol abuse.

A glucagon blood test measures the amount of a hormone called glucagon in your blood. Glucagon is produced by cells in the pancreas. It helps control your blood sugar level by increasing blood sugar when it is too low.

C-peptide is a substance, a short chain of amino acids, that is released into the blood as a byproduct of the formation of insulin by the pancreas. This test measures the amount of C-peptide in a blood or urine sample.

In the pancreas, within specialized cells called beta cells, proinsulin, a biologically inactive molecule, splits apart to form one molecule of C-peptide and one molecule of insulin. Insulin is vital for the transport of glucose into the body's cells and is required on a daily basis. When insulin is required and released from the beta cells into the blood in response to increased levels of glucose, equal amounts of C-peptide are also released. Since C-peptide is produced at the same rate as insulin, it is useful as a marker of insulin production.

In particular, C-peptide testing can be used to help evaluate the production of insulin made by the body (endogenous) and to help differentiate it from insulin that is not produced by the body but is taken in as diabetic medication (exogenous) and so does not generate C-peptide. This test may be done in conjunction with an insulin test.

Blood sugar (glucose) is usually present in the urine at very low levels or not at all. Abnormally high amounts of sugar in the urine, known as glycosuria, are usually the result of high blood sugar levels. High blood sugar usually occurs in diabetes, especially when untreated. It serves as the main source of energy used by the body. Insulin is a hormone that helps the body's cells to use the glucose. Excess or shortage of insulin in the body causes an imbalance of the blood glucose in the body, leading to its severe drop or drastic increase in the blood. Blood glucose levels that remain high over time can cause damage to the eyes, kidneys, nerves and blood vessels. Chronic low glucose levels can lead to brain and nerve damage.

Fasting blood sugar is a test for glucose content in a person’s blood that, as the name suggests, is conducted after fasting. The test is generally carried out in the morning, after an overnight fasting. As a part of the test, a sample of the patient’s blood is collected and then sent to the lab for testing.

A fasting blood sugar test offers information about how the body is managing the blood sugar levels. Normally, the range of glucose in a person’s blood is between 70 to 100 mg/dl. Fasting blood sugar levels between 100 to 126 mg/dl are considered as pre-diabetic or impaired fasting glucose and blood sugar levels of 126 mg/dl or higher are diagnosed as diabetes.

This is a blood test to check for diabetes. If you have diabetes, your body doesn't make enough insulin to keep your blood sugar in check. This means your blood sugar levels are too high, and over time this can lead to serious health problems including nerve and eye damage.

This test is done to see how your body responds to sugar and starch after you eat a meal. As you digest the food in your stomach, blood glucose, or blood sugar, levels rise sharply. In response, your pancreas releases insulin to help move these sugars from the blood into the cells of muscles and other tissues to be used for fuel. Within two hours of eating, your insulin and blood glucose levels should return to normal. If your blood glucose levels remain high, you may have diabetes.

Blood sugar (glucose) is usually present in the urine at very low levels or not at all. Abnormally high amounts of sugar in the urine, known as glycosuria, are usually the result of high blood sugar levels. High blood sugar usually occurs in diabetes, especially when untreated. It serves as the main source of energy used by the body. Insulin is a hormone that helps the body's cells to use the glucose. Excess or shortage of insulin in the body causes an imbalance of the blood glucose in the body, leading to its severe drop or drastic increase in the blood. Blood glucose levels that remain high over time can cause damage to the eyes, kidneys, nerves and blood vessels. Chronic low glucose levels can lead to brain and nerve damage.

The term HbA1c refers to glycated haemoglobin. It develops when haemoglobin, a protein within red blood cells that carries oxygen throughout your body, joins with glucose in the blood, becoming 'glycated'.

By measuring glycated haemoglobin (HbA1c), clinicians are able to get an overall picture of what our average blood sugar levels have been over a period of weeks/months.

For people with diabetes this is important as the higher the HbA1c, the greater the risk of developing diabetes-related complications. 

HbA1c is also referred to as haemoglobin A1c or simply A1c.

Gonadotropin-releasing hormone (GnRH) stimulation test is the gold standard to identify central precocious puberty (CPP). This test requires multiple blood samples at different time points to measure gonadotropin levels, and is therefore expensive, time-consuming, and uncomfortable for patients. We aimed to simplify the GnRH stimulation test to require fewer blood samples.

Growth hormone (GH) is a hormone that is essential for normal growth and development in children. It promotes proper linear bone growth from birth through puberty. In both children and adults, growth hormone helps regulate the rate at which the body both produces energy from food (metabolism) and makes lipids, proteins, and glucose (sugar). It also helps regulate the production of red blood cells and muscle mass.

Growth hormone is produced by the pituitary gland, a grape-sized gland located at the base of the brain behind the bridge of the nose. It is normally released into the bloodstream in pulses throughout the day and night with peaks that occur mostly during the night. Because of this, a single measurement of the level of GH in blood is difficult to interpret and not usually clinically useful. The value will be higher if the sample is taken during a pulse and lower if it is taken during a period between pulses. GH stimulation and suppression tests are therefore often used to diagnose GH abnormalities. (See the "How is it used?" section.)

GH deficiency

Children with insufficient GH production grow more slowly and are smaller in size for their age. Some children have GH deficiency at birth (congenital), but some may develop a deficiency later due, for example, to a brain injury or tumor. These conditions can affect the pituitary gland, causing a decrease in pituitary function, resulting in a lowered production of pituitary hormones (hypopituitarism). Sometimes, the cause of the deficiency is not known.

In adults, growth hormone plays a role in regulating bone density, muscle mass, and glucose and lipid metabolism. It can also affect heart and kidney function. Deficiencies may have begun in childhood or develop in adulthood. A deficiency can develop, for example, because of damage to the pituitary gland caused by a head injury, brain tumor, or surgery or radiation treatment. This can result in a decrease in pituitary hormones (hypopituitarism). The deficiency in GH can lead to decreased bone density, less muscle mass, and altered lipid levels. However, testing for GH deficiency is not routine in adults who have decreased bone density and/or muscle strength or increased lipids. GH deficiency is a very rare cause of these disorders.

A growth hormone (GH) test measures the amount of human growth hormone (GH) in the blood. GH is made by the pituitary gland and is needed for growth. It plays an important role in how the body uses food for energy (metabolism). The amount of GH in the blood changes during the day and is affected by exercise, sleep, emotional stress, and diet.

Too much GH during childhood can cause a child to grow taller than normal (gigantism). Too little GH during childhood can cause a child to grow less than normal (dwarfism). Both conditions can be treated if found early.

In adults, too much GH is caused by a noncancerous tumor of the pituitary gland (adenoma). Too much GH can cause bones of the face, jaw, hands, and feet to grow larger than normal (acromegaly).

Growth hormone can cause the release of other substances (factors) that affect growth and metabolism. One of these is insulin-like growth factor 1 (IGF-1). When the GH level is very high, the IGF-1 level is also very high. A test for IGF-1 may also be done to confirm high GH levels.

Growth hormone promotes development from birth to puberty. It is also essential for the maintenance of metabolism, skeletal muscle, and bone tissue throughout one’s life

The pituitary gland, located at the base of the brain, releases growth hormone in periodic bursts. Most growth hormone is released during deep sleep

They hypothalamus of the brain in turn releases hormones that control growth hormone release by the pituitary gland. Growth hormone-releasing hormone (GH-RH) and growth hormone-inhibiting hormone (GH-IH) stimulate and depress growth hormone secretion, respectively

Growth hormone affects nearly every cell in the body. It causes cells to increase their protein production and their fatty acid metabolism

The growth-inducing effects of growth hormone are important for adaptation to strenuous demands, such as exercise. Growth hormone also stimulates the replenishment of tissues during everyday wear and tear. The hormone is especially important during childhood development

Problems with the pituitary gland or GH-RH may cause growth hormone underproduction. This results in stunted growth, abnormal fat distribution, and difficulty regulating blood sugar

Excessive production of growth hormone, caused by tumors or problems with the regulatory mechanisms, may cause excessive growth. The resulting conditions, though similar, differ depending on the stage in life that a growth hormone overproduction occurred:

Growth hormone overproduction before puberty results in gigantism. This is marked by extreme lengthening of the skeleton, sometimes causing heights in excess of 8 feet

Growth hormone overproduction during adulthood results in acromegaly. Because the bones have already reached their maximum length, acromegaly is marked by bone thickening but not lengthening

The Growth Hormone-Releasing Hormone Blood Test helps measure the levels of growth hormone-releasing hormone in blood. It is used to differentiate between a pituitary tumor and an ectopic secretion of GH-RH

If GH-RH levels are normal, the result of excessive growth hormone is likely a tumor of the pituitary gland that releases growth hormone without the need for stimulation by GH-RH

If GH-RH levels are increased, there may be an ectopic tumor of the hypothalamus that secretes GH-RH

Growth hormone (GH) is secreted in a pulsatile manner and is cleared rapidly, resulting in dramatic fluctuations in GH levels.1-3 For this reason, random GH levels are generally not useful in establishing GH deficiency. A number of physiologic and pharmacologic stimuli can be used to provoke GH release. Several growth hormone stimulation protocols are described below. These tests are best performed in the morning after an overnight fast.3 Patients should be confirmed as euthyroid before these protocols are initiated.

At least 3 blood samples are taken.

The test is done in the following way:

The first blood sample is collected between 6 a.m. and 8 a.m before you eat or drink anything.

You then drink a solution containing glucose (sugar). You may be told to drink slowly to avoid becoming nauseated. But you must drink the solution within 5 minutes to ensure the test result is accurate.

The next blood samples are usually collected for 1 to 2 hours after you finish drinking the glucose solution. Sometimes they are taken every 30 or 60 minutes.

Each sample is sent to the laboratory right away. The lab measures the glucose and growth hormone (GH) levels in each sample.

A glucose tolerance test measures how well your body’s cells are able to absorb glucose, or sugar, after you ingest a given amount of sugar. Doctors use fasting blood sugar levels and hemoglobin A1c values to diagnose type 1 and type 2 diabetes, and prediabetes. A glucose tolerance test can also be used. Doctors primarily use a glucose tolerance test to diagnose gestational diabetes.

Doctors often diagnose type 1 diabetes quickly because it usually develops quickly and involves high blood sugar levels. Type 2 diabetes, on the other hand, often develops over years. Type 2 diabetes is the most common form of diabetes, and it usually develops during adulthood.

Gestational diabetes occurs when a pregnant woman who doesn’t have diabetes before pregnancy has high blood sugar levels as a result of the pregnancy. The American Diabetes Association estimates that gestational diabetes occurs in 9.2 percent of pregnancies.