Online Medical Dictionary

Letter R

Radiation Fibrosis: Chronic scarring of the lung(s) induced by exposure to ionizing radiation.
Radiation Menopause: An early onset of the menopause period a the woman's life, induced by exposure to radiation.
Radiation Therapy: A therapy to treat cancer or other conditions by use of ionizing radiation focused at a particular area of the body where malignant cells or tissues or otherwise needed areas for treatment are located. Also called radiation oncology or radiotherapy, a specialist for wich is titled a radiation therapist, radiation oncologist or radiotherapist.
Radiologist: A physician specialized in the use of various imaging technologies which use forms of radiation to produce images of the body, and the ability to interpret these images.
Radiology: The branch of medicine focused in procuring and interpreting intrinsic images of the body by use of a variety of forms of ionizing and non-ionizing radiation, in aim to provide diagnosis and treatment of several conditions and diseases. These imaging techniques include magnetic resonance imaging (MRI), computed tomography (CT scan), position emission tomography (PET scan), ultrasound, and nuclear medicine.
Radiotherapy: See Radiation Therapy.
Rapid Eye Movement Sleep (REM): Accounting for roughly one quarter of the average person's total sleep, REM is the tonic and phasic sleep phases in which motor neurons remain unstimulated, thus muscles are in a fixed state. However other brain functions appear to be operating as they do during in waking hours. REM is the portion of the sleep cycle from which vivid dreams are most often recalled.
Rash: A condition of the skin, often marked by blotchy red patterns of colouration, bumpiness or itch, incited by a variety of different factors, such as allergens, stress, friction, virus, irritation, pregnancy or infection.
Raynaud's Disease: A vasospastic condition believed to be caused by a reduction of blood flow to the fingers and/or toes as a result of vasospasm, the spasm of blood vessels, which can lead to vasoconstriction. Fingers and/or toes affected can become discoloured when triggered by temperature changes or emotional or stressful events. May occur with rheumatoid arthritis or as a standalone condition. Raynaud's disease, or Primary Raynaud's phenomenon, is said to be an idiopathic condition, that is one incited by unknown cause, while Raynaud's Phenomenon is said to be triggered by temperature or circumstance.
RBC: Abbreviation for red blood cells.
Recessive, autosomal: A genetic condition which will appear in individuals who receive one copy of a mutated autosomal (of an autosome, a non-sex chromosome) gene from each carrier parent. As each parent has only one copy of the autosomal gene, they themselves will not exhibit the recessive trait as the train requires a counterpart gene from which to manifest.
Recessive, X-linked: A genetic condition which will appear in individuals if a mutation on a gene of the X chromosome incites the condition. Males are said to be hemizygous for an X-linked recessive gene mutation, as they are composed of only one X chromosome. For example, Duchenne muscular dystrophy is an X-linked recessive disorder, thus its higher prevalence among males. Women will be considered homozygous for the condition, because they will require that the gene mutation occurs on both of their X chromosomes.
Rectal Cancer: One of the colorectal cancers of the large bowel, wherein malignancy develops from the tissues of the rectum, or more often metastasizes to the rectum from a cancer of a surrounding tissue such as cancerous colon polyps. Colectoral cancers account for one of the highest amount of cancer-related fatalities in the developed world.
Rectum: The end of large intestine, which functions to store solid waste until it exited through the anus.
Red Blood Cell: Erythrocytes, the body's foremost transporter of oxygen, made possible by the binding capabilities of the cells' composite hemoglobin. Red blood cells deliver oxygen from the lungs to the tissues of the body through the circulatory system. The body produces roughly 2.4 million new red blood cells every second.
Red Cell Count: The amount of red blood cells found in a volume of blood.
Reduction Mammaplasty: Breast reduction surgery.
Regression: The worsening of a condition or disease, or a return to its former state after a period of progression.
Regulatory T cell: T cell s which function to regulate the activity of other T cells, usually by means of repressing their activities.
Reinnervate: See Reinnervation.
Reinnervation: Restoration of or an increase in the capabilities of nerve function due to the formation of new synapses formed by post-synaptic neurons, or an increased output seen by already existent synaptic neurons compensating for dead or impaired pre-synaptic neurons. May occur naturally or as incited by medical procedure.
Reiter Syndrome: An autoimmune condition incited by bacterial infection. Reiter's syndrome inspires symptoms usual to arthritis, such as inflammation of common joints such as the knee, and back, as well as conjunctivitis (eye inflammation) and blister-like skin lesions. Treatment focuses primarily on treating the inciting infection, usually by antibiotic, and in severe cases immunosuppressants and/or steroids may need be implemented.
REM Sleep: See Rapid Eye Movement Sleep.
Remission: A temporary or permanent absence of an incurable chronic condition or disease in a diagnosed individual. Remission is most commonly used in reference to cancer, wherein a malignancy is said to be in partial remission if the cancerous tumour or neoplasm has been found to have decreased in size by at least half of its original size, or in complete remission if all indications of the disease have ceased to be present.
Remote Telesurgery: Surgery performed remotely, that is a surgeon oversees a surgical procedure from a location other than that in which the procedure is taken place, by means of high-tech robotics technology and telecommunication systems.
Renal: Regarding the kidney(s).
Renal Calculi: See Kidney stones.
Renal Cancer: See Kidney Cancer.
Renal Cell Carcinoma: Hypernephroma, a cancer of the kidney developing in the lining of the tiny renal tubes which function to filter waste from the blood. Renal cell cancer is the most common of kidney cancers among adults. Risk for developing renal cell carcinoma appears to be increased in individuals who have undergone hysterectomy, who smoke, or who are obese. Treatment includes surgery if the cancer has not metastasized, and immunotherapies if it has. Chemotherapy has been shown to be ineffective in treating most cases of renal cell carcinoma.
Renal Osteodystrophy: A deficiency in bone mineralization induced by the impeded or affected electrolyte and endocrine capabilities symptomatic of chronic kidney disease. This bone pathology is also termed chronic kidney disease-mineral and bone disorder. Treatment includes mineral supplementation, implementation of phosphate binders, kidney transplant, or in some cases a virtually daily regimen of hemodialysis has been found to improve the condition.
Renal Stone: See Kidney Stone.
Renal Transplant: See Kidney Transplant.
Respiratory Failure: Failure of the lungs to perform the basic function of air exchange; the retention of oxygen from inhaled air to disperse to the body in blood, and the expulsion of carbon dioxide from the body through exhale back into the environment.
Retinal Detachment: The separation of the retina from its support tissue, localized to a portion of the retina or involving detachment of the entire retina, which would result in blindness. Retinal detachment can occur due to inflammation caused by a retinal break, fibrous tissue build-up caused by injury, fluid pressure or, in rare case, a cancerous tumour of choroid tissues situated beneath the retina. Treatment aims at removing the cause of the divide and sealing the break, usually by surgery or laser photocoagulation if the detachment is confined.
Retinal Disease: See Retinopathy.
Retinopathy: Any non-inflammatory disease or condition of the retina, not resulting from injury. Causes may include diabetes, sickle cell disease or genetic disorders.
Retinoschisis: A disease of the retina in which the the retina's neurosensory layers are caused to split, often aysmtomatic but smetimes resulting in impeded vision. May be degenerative, in which case cause is largely unknown, hereditary, tractional or exudative.
Retrograde Amnesia: The inability to recall memories of events or experiences that occurred prior to the onset of amnesia, induced by an injury affecting the brain. The closer the time-frame to the incident, thw greater the inability to recall.
Rheumatism: A term losing reference in the medical field, but commonly used colloquially to describe problematic conditions of the tendons, joints, connective tissues, muscles and/or bones.
Rheumatoid Arthritis: A chronic, autoimmune inflammatory disease affecting a variety of tissues, joints and organs, causing the body to erroneously attack its own synovial joints. Rheumatoid arthritis may induce lung fibrosis, renal complications and localized osteoporosis, among a variety of other conditions. Treatment focuses on pain and symptom relief, as at present the condition is not curable. Rheumatoid arthritis is believed to be genetically linked.
Rhino-: Prefix defining a relationship to the nose.
Rhinoplasty: Cosmetic surgery conducted to improve the appearance of the nose, or reconstructive surgery conducted to improve the function of the nose.
Rickets: Osteomalacia, or a softening of bones, a condition appearing with prevalence in children of developing countries suffering from malnutrition. Rickets is largely due to a Vitamin D deficiency and also affected by lack of calcium in the diet. Treatment includes vitamin supplementation, proper diet and increased exposure to sunlight.
Ringing in the Ears: See Tinnitus.
RNA: Abbreviation for ribonucleic acid.
Rod: The photoreceptor cells of the retina that help to provide peripheral vision and low-light, or night vision.
Rosacea: Chronic skin disease causing redness. Believed to be incited by bacteria or increased levels of mites. Treatment includes cosmetics and sometimes prescribed antibiotics.
Rx: Symbol for medical prescription.