In-depth

Acanthosis nigricans

Addison's disease

Addison's disease occurs when your adrenal glands produce insufficient amounts of certain important hormones. Treatment may include taking corticosteroids.

Alcoholic hepatitis

Alcohol can severely damage your liver — even moderate drinkers aren't immune. Learn more about this serious liver disease.

Amyloidosis

Angina

Anorexia nervosa

Ascariasis

Aspergillosis

Bile reflux

Binge-eating disorder

Blind loop syndrome

C. difficile

C. difficile can be a life-threatening infection. It typically develops when antibiotics destroy other bacteria in your intestines, allowing C. difficile to flourish.

Cancer

Carcinoid tumors

Carcinoid tumors are rare, slow-growing cancerous tumors that most often occur in the gastrointestinal tract or in the lungs.

Castleman disease

Celiac disease

Celiac disease is an immune reaction to gluten, a protein found in certain foods. As a result, the body is unable to absorb some important nutrients.

Chronic lymphocytic leukemia

Chronic lymphocytic leukemia is a cancer of the blood and bone marrow. Unlike other cancers, this form of leukemia doesn't always initially require treatment.

Chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a rare type of blood cancer. New treatments may be improving the prognosis for many people with CML.

Churg-Strauss syndrome

Churg-Strauss syndrome is a rare disorder marked by blood vessel inflammation that affects organs throughout the body. Asthma is the most common sign.

Cirrhosis

Colon cancer

Colon cancer and rectal cancer combined are the second-leading cause of cancer-related deaths in the United States. Regular screening tests can help reduce your risk.

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia is a genetic condition affecting the adrenal glands and interfering with normal growth and development in boys and girls.

Crohn's disease

Cryptosporidium infection

Cryptosporidium infection may cause diarrhea in healthy people, but for people with HIV/AIDS and weakened immune systems, the illness can cause serious complications.

Cyclospora infection

Depression

Dermatomyositis

Diabetes

Diabetes affects how your body uses blood sugar. Too much blood sugar over long periods can cause serious health problems, but treatments are available.

Diabetes insipidus

Diabetes insipidus is a rare condition characterized by intense thirst and the excretion of large amounts of urine.

Diabetic neuropathy

Drug addiction

Dysphagia

Ebola virus and Marburg virus

Esophageal cancer

Reduce your risk of esophageal cancer by eating more fruits and vegetables.

Fibromuscular dysplasia

Fibromuscular dysplasia is a rare, but treatable, condition in which the arteries to your kidneys, brain or abdomen narrow, reducing blood flow to your organs.

Gallbladder cancer

Gastroparesis

Giant cell arteritis

Giant cell arteritis causes inflammation in your arteries, particularly those in your head. Early treatment often relieves symptoms and prevents vision loss, a serious complication.

Giardiasis

Giardia infection is a common waterborne illness. Learn the symptoms and reduce your risk.

Graves' disease

H. pylori infection

Hairy cell leukemia

Histoplasmosis

HIV/AIDS

Hodgkin's lymphoma

Hyperthyroidism

Hyperthyroidism occurs when your thyroid gland produces too much of the hormone thyroxine — speeding up your metabolism and sometimes leading to serious complications.

Hypopituitarism

In hypopituitarism, your pituitary gland produces too little — or none — of one or more hormones. Disruption of any number of routine body functions can result.

Intestinal ischemia

Kidney cancer

Lead poisoning

Leukemia

Liver cancer

The risk of liver cancer may be reduced by protecting yourself from serious liver diseases such as cirrhosis and hepatitis B and C.

Lung cancer

Smoking increases your risk of lung cancer. Quit now and reduce your risk.

Mesothelioma

Mesothelioma is a type of cancer closely linked to asbestos exposure. Find out the signs and symptoms of malignant mesothelioma and how to protect yourself.

Multiple myeloma

Neuroblastoma

Neuroblastoma most commonly affects children age 5 and younger. It's the most common form of cancer in babies.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease is associated with obesity and diabetes. Lifestyle changes may prevent it from becoming serious.

Non-Hodgkin's lymphoma

Norovirus infection

Noroviruses cause an intestinal flu-like illness that typically resolves within days. Norovirus infection is highly contagious, especially in closed settings like hospitals and cruise ships.

Pancreatic cancer

Pancreatic cancer is often fatal. Find out which new treatments offer hope.

Pancreatitis

The pain of pancreatitis, an inflammation of the pancreas, can last for days, or in chronic cases, for years. Pancreatitis can lead to serious complications.

Peptic ulcer

Peptic ulcers are painful sores that commonly affect the lining of your stomach and upper small intestine. The most frequent cause is a treatable infection.

Pheochromocytoma

Pituitary tumors

Pituitary tumors are abnormal growths in the pituitary gland in the brain. Most are noncancerous (benign). Some may cause overproduction of hormones and associated problems.

Polymyalgia rheumatica

Prescription drug abuse

Primary sclerosing cholangitis

Pulmonary fibrosis

Pulmonary fibrosis results from scar tissue that forms in your lungs. This affects your ability to breathe and obtain enough oxygen.

Pyloric stenosis

Comprehensive overview covers symptoms, treatment of this uncommon digestive condition in infants.

Recurrent breast cancer

Rheumatoid arthritis

Seasonal affective disorder (SAD)

Sheehan's syndrome

Sheehan's syndrome is a rare pituitary gland disorder that occurs in women usually as a result of severe blood loss during childbirth.

Stomach cancer

Reduce your risk of stomach cancer by eating more fruits and vegetables.

Takayasu's arteritis

Takayasu's arteritis is an uncommon form of vasculitis that affects the large arteries.

Tapeworm infection

Teen depression

All teens feel down from time to time. But if negative feelings persist or start to interfere with daily life, it might be depression.

Throat cancer

The most common throat cancers are linked to smoking and excessive alcohol use.

Thyroid nodules

Most thyroid nodules — lumps in the thyroid gland — cause no problems. But nodules that affect swallowing, produce excess thyroid hormone or are malignant require treatment.

Toxic hepatitis

Toxic hepatitis is liver damage that occurs when your liver isn't able to break down certain toxins — including common pain relievers such as Tylenol.

Tuberculosis

Type 1 diabetes

Type 1 diabetes in children

Type 1 diabetes is a lifelong — sometimes frightening — condition, but it doesn't need to slow your child down. Learn more about managing type 1 diabetes.

Type 2 diabetes

Type 2 diabetes in children

Typhoid fever

Ulcerative colitis

Valley fever

Vasculitis

Vitamin deficiency anemia

Lacking certain vitamins can lead to vitamin deficiency anemia. Find out which vitamins are linked to this condition.

Wegener's granulomatosis

Wegener's granulomatosis is an uncommon disease that causes blood vessel inflammation that can damage lungs, kidneys and other organs. Untreated, it can be fatal.

Whipple's disease

Whipple's disease is a rare bacterial infection that affects primarily the gastrointestinal system, and can be treated successfully with antibiotics.

Zollinger-Ellison syndrome

In Zollinger-Ellison syndrome, tumors in the pancreas or duodenum secrete a hormone called gastrin that leads to excessive stomach acid and ulcers.

Aug. 26, 2014