Use the A-Z list to browse more than 6,000 health-related topics in our library. Clicking on a term opens the definition and, in most cases, links to more information.
Also Known As: "Heterogeneous Nuclear RNA, mRNA, Ribonucleic Acid, hRNA, Transfer RNA, Polynucleotides, Messenger RNA, tRNA"
A substance similar to DNA that is found in every cell of the body. Its functions include protein synthesis and relaying genetic information. There are four main types: heterogeneous (hRNA), messenger (mRNA), transfer (tRNA) and ribosomal (rRNA).
"RNIs" is more commonly referred to as "Recommended Nutrient Intakes" in the medical community. Recommended Nutrient Intakes
Dietary standards used in Canada that are the equivalent of the U.S. recommended dietary allowances (RDAs) More Information on Recommended Nutrient Intakes: Nutrition Basics
Mechanical arms that are being developed to assist with some minimally invasive surgeries. The robotic arms are much smaller than human hands, allowing physicians to perform procedures through small incisions instead of doing open-heart surgery.
Surgery that uses a voice-activiated robot equipped with a camera and controlled by a surgeon. Because the robot's 'hands' are smaller than the surgeon's, a much smaller incision can be used. It is being tested for use during bypass surgery in the U.S.
Also Known As: "RMSF, Rickettsia Rickettsii Infection"
A bacterial infection spread by the bite of a wood tick. It is characterized by spots on the skin, fever, loss of appetite, coughing, difficulty breathing and abdominal pain. More Information on Rocky Mountain Spotted Fever: Cold & Flu Basics
"Roentgen Rays" is more commonly referred to as "X ray" in the medical community. X ray
Also Known As: "Radiograph, Roentgenogram, Roentgenography"
An image of a body part, organ or bodily system on film paper or fluorescent screens. It is produced by using low doses of radiation. More Information on X ray: Imaging Tests
"Roentgenogram" is more commonly referred to as "X ray" in the medical community. X ray
Also Known As: "Roentgenography, Radiograph, Roentgen Rays"
An image of a body part, organ or bodily system on film paper or fluorescent screens. It is produced by using low doses of radiation. More Information on X ray: Imaging Tests
"Roentgenography" is more commonly referred to as "X ray" in the medical community. X ray
Also Known As: "Radiograph, Roentgen Rays, Roentgenogram"
An image of a body part, organ or bodily system on film paper or fluorescent screens. It is produced by using low doses of radiation. More Information on X ray: Imaging Tests
"Rofecoxib" is more commonly referred to as "Vioxx" in the medical community. Vioxx
A brand of Cox 2 inhibitor, medications similar to NSAIDs but that should not cause stomach upset. It was withdrawn from the market in 2005. More Information on Vioxx: Heart Drug & Medication
"Roger's Disease" is more commonly referred to as "Ventricular Septal Defect" in the medical community. Ventricular Septal Defect
Also Known As: "Interventricular Septal Defect, VSD"
A heart defect characterized by a hole in the wall (septum) that divides the two ventricles. More Information on Ventricular Septal Defect: Pediatric Heart
A genetic mutation that causes a woman to be born without a vagina, cervix, uterus or fallopian tubes. More Information on Rokitansky Kuster Hauser Syndrome: Birth & Genetic Disorders
A form used by health professionals to categorize the disability of persons with chronic pain. More Information on Roland Morris Disability Scale: Pain Basics
One way that oats may be processed (can also be crushed or cut). Oatmeal is typically rolled whole oats. More Information on Rolled Oats: Functional Foods
"Rolling Hiatal Hernia" is more commonly referred to as "Paraesophageal Hiatal Hernia" in the medical community. Paraesophageal Hiatal Hernia
Also Known As: "Parahiatal Hernia, Paraesophageal Hiatus Hernia"
A hiatal hernia that occurs when a portion of the stomach squeezes through the opening of the diaphragm and becomes positioned next to the esophagus. More Information on Paraesophageal Hiatal Hernia: GERD & Heartburn
"ROM" is more commonly referred to as "Range of Motion" in the medical community. Range of Motion
The entire amount of motion that joints can be moved in a certain direction. Range-of-motion exercises are often used to help patients overcome pain located in the arms, legs and other body areas. More Information on Range of Motion: Pain Basics
"Romano-Ward Syndrome" is more commonly referred to as "Long QT Syndrome" in the medical community. Long QT Syndrome
Also Known As: "Inherited Long QT Syndrome, LQTS"
Long QT syndrome (LQTS) is a rare, usually inherited and sometimes fatal disorder of the heart's electrical system. It may lead to a rapid heartbeat in times of stress, fear or anger, which can cause fainting or even cardiac arrest. More Information on Long QT Syndrome: Arrhythmia
Nearly all romantic relationships have periods of trouble. Objective, non-accusative discussion can help. Therapy can provide a neutral ground and can guide these discussions as well as providing constructive new ways to look at the problems. More Information on Romantic Relationships: Relationships
A term used to describe illicit use of flunitrazepam, a "date-rape drug." A person who takes the drug may become incapacitated and vulnerable to sexual assault. Mixing the drug with alcohol can be fatal.
The portion of a tooth that is located and secured in the tooth socket and is covered by cementum instead of enamel. More Information on Root: Oral Health Basics
The part of the pulp cavity located inside the root of a tooth. The term may also be used to describe root canal treatment, in which diseased or infected pulp is removed. More Information on Root Canal: Dental Restorations
Also Known As: "Endodontic Treatment, Endodontic Therapy, Endodontic Microsurgery"
Treatment for a diseased or infected root canal. The affected pulp is removed and the root canal is cleaned and reshaped before it is filled with gutta percha to prevent reinfection. An artificial crown is typically used to improve tooth strength. More Information on Root Canal Therapy: Dental Restorations
Also Known As: "Endodontic Treatment, Endodontic Therapy, Endodontic Microsurgery, Root Canal Therapy"
Treatment for a diseased or infected root canal. The affected pulp is removed and the root canal is cleaned and reshaped before it is filled with gutta percha to prevent reinfection. An artificial crown is typically used to improve tooth strength. More Information on Root Canal Treatment: Dental Restorations
A common and conservative treatment of periodontal disease that involves the removal of microbes, bacteria, tartar, diseased tissue and irregularities on the surfaces of the root and within a periodontal pocket. More Information on Root Planing: Dental Restorations
The removal of one entire root and possibly a portion of the crown from a tooth that has multiple roots. Generally requires a root canal treatment before or after the procedure. More Information on Root Resection: Dental Restorations
A skin disorder leading to redness and pimples on the nose, forehead, cheekbones and chin. It often looks like acne, but blackheads are almost never present. Most often affects women with fair skin, ages 30 to 50. More Information on Rosacea: Acne & Blemish
"Rosary Bead Esophagus" is more commonly referred to as "Symptomatic Diffuse Esophageal Spasm" in the medical community. Symptomatic Diffuse Esophageal Spasm
Also Known As: "Spastic Pseudodiverticulosis, Corkscrew Esophagus"
Widespread spasms of the muscles of the esophagus causing chest pain and difficulty swallowing.
Also Known As: "Roseola Infantum, Sixth Disease, Baby Measles, Exanthem Subitum, Pseudorubella"
An acute viral infection that affects infants and small children. Symptoms include high fever and skin rash. More Information on Roseola: Skin Related Infections
Also Known As: "Sixth Disease, Baby Measles, Exanthem Subitum, Pseudorubella"
An acute viral infection that affects infants and small children. Symptoms include high fever and skin rash. More Information on Roseola Infantum: Skin Related Infections
A type of antidiabetic agent used in the treatment of type 2 diabetes. It works by lowering the levels of glucose circulating in the body and may be used alone or in combination with other antidiabetics. More Information on Rosiglitazone: Diabetes & Endocrine Drugs
Also Known As: "Pulmonary Autotransplant, Pulmonary Autograft"
A surgery that replaces a severely defective aortic valve. The defective aortic valve is replaced by the patient's own pulmonary valve, which is then replaced with a valve from another human body. More Information on Ross Operation: Pediatric Heart
Also Known As: "Pulmonary Autotransplant, Ross Operation, Pulmonary Autograft"
A surgery that replaces a severely defective aortic valve. The defective aortic valve is replaced by the patient's own pulmonary valve, which is then replaced with a valve from another human body. More Information on Ross Procedure: Pediatric Heart
An arbovirus of the genus Alphavirus that causes flu-like illness. It is spread by a mosquito bite and is most common in rural areas of Australia. More Information on Ross River Virus: Infectious Disease Basics
An arbovirus of the genus Alphavirus that causes flu-like illness. It is spread by a mosquito bite and is most common in rural areas of Australia. More Information on Ross River Virus Infection: Infectious Disease Basics
A tiny drill-like device used in a catheter-based procedure called rotational atherectomy to grind away plaque from an artery wall. More Information on Rotablator: Catheter Tests & Procedures
"Rotational Atherectomy" is more commonly referred to as "Atherectomy" in the medical community. Atherectomy
Also Known As: "Coronary Atherectomy, Peripheral Atherectomy, Extractional Atherectomy, Transluminal Extraction, Mechanical Rotational Atherectomy, Directional Atherectomy, Directional Coronary Atherectomy"
A broad name for a group of related procedures that remove exceptionally hard (calcified) plaque that has built up on the walls of the arteries. More Information on Atherectomy: Catheter Tests & Procedures
The group of muscles and tendons that act to stabilize the shoulder. Overuse or wear and tear associated with aging or an accident can injure the rotator cuff. More Information on Rotator Cuff: Back, Neck & Shoulder Pain
Also Known As: "Rotator Cuff Sprain, Rotator Cuff Tear, Rotator Cuff Strain"
Injury to the muscles and tendons that connect the upper arm bone (humerus) to the shoulder blade and stabilize the shoulder. These injuries are due to poor posture, falling, lifting and repetitive overhead arm activities. More Information on Rotator Cuff Injury: Back, Neck & Shoulder Pain
Also Known As: "Rotator Cuff Tear, Rotator Cuff Strain"
Injury to the muscles and tendons that connect the upper arm bone (humerus) to the shoulder blade and stabilize the shoulder. These injuries are due to poor posture, falling, lifting and repetitive overhead arm activities. More Information on Rotator Cuff Sprain: Back, Neck & Shoulder Pain
Also Known As: "Rotator Cuff Sprain, Rotator Cuff Tear"
Injury to the muscles and tendons that connect the upper arm bone (humerus) to the shoulder blade and stabilize the shoulder. These injuries are due to poor posture, falling, lifting and repetitive overhead arm activities. More Information on Rotator Cuff Strain: Back, Neck & Shoulder Pain
Also Known As: "Rotator Cuff Strain, Rotator Cuff Sprain"
Injury to the muscles and tendons that connect the upper arm bone (humerus) to the shoulder blade and stabilize the shoulder. These injuries are due to poor posture, falling, lifting and repetitive overhead arm activities. More Information on Rotator Cuff Tear: Back, Neck & Shoulder Pain
Also Known As: "Infantile Diarrhea, Acute Nonbacterial Infectious Gastroenteritis, Winter Diarrhea, Acute Viral Gastroenteritis, Winter Virus"
A virus that causes diarrhea, especially in young children. This is the leading cause of diarrhea in American children under the age of 2 years and also causes vomiting. More Information on Rotavirus: Pediatric Digestive
Also Known As: "Rotavirus Enzyme Immunoassay Test, Rotavirus EIA Test"
A fecal test that detects Group A rotavirus antibodies in a stool sample collected when the patient has ongoing diarrhea (the acute phase of the infection). More Information on Rotavirus Antigen Test: Digestive Lab Tests
Also Known As: "Rotavirus Enzyme Immunoassay Test"
A fecal test that detects Group A rotavirus antibodies in a stool sample collected when the patient has ongoing diarrhea (the acute phase of the infection). More Information on Rotavirus EIA Test: Digestive Lab Tests
A fecal test that detects Group A rotavirus antibodies in a stool sample collected when the patient has ongoing diarrhea (the acute phase of the infection). More Information on Rotavirus Enzyme Immunoassay Test: Digestive Lab Tests
A tiny drill-like device used in a catheter-based procedure called rotational atherectomy to grind away plaque from an artery wall. More Information on Roto Rooter: Catheter Tests & Procedures
Also Known As: "Intestinal Roundworm, Zoonotic Roundworm, Roundworm Infection, Parasitic Roundworm"
Infection with any of a group of invertebrates with long, round bodies. Examples include enterobiasis, ascariasis, ancylostomiasis, trichuriasis, strongyloidiasis, toxocariasis and trichinosis. More Information on Roundworm: Infectious Disease Basics
Also Known As: "Intestinal Roundworm, Zoonotic Roundworm, Parasitic Roundworm"
Infection with any of a group of invertebrates with long, round bodies. Examples include enterobiasis, ascariasis, ancylostomiasis, trichuriasis, strongyloidiasis, toxocariasis and trichinosis. More Information on Roundworm Infection: Infectious Disease Basics
"Roux en Y Gastric Bypass" is more commonly referred to as "Gastric Bypass" in the medical community. Gastric Bypass
Also Known As: "Stomach Bypass, Gastric Bypass Procedure, Gastric Bypass Surgery, Gastric Bypass Operation"
The surgical closing of a part of the stomach, resulting in a much smaller stomach size. It may be used to treat obesity. More Information on Gastric Bypass: Bariatric Surgery
"Roxicet" is more commonly referred to as "Tylenol" in the medical community. Tylenol
A brand of acetaminophen, over-the-counter nonaspirin medication used to relieve pain and reduce fever (but not inflammation). It belongs to the family of drugs called analgesics. More Information on Tylenol: Pain Medications
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