Medical Dictionary
Radiation
| Energy in the form of wavelengths or particles, which include: gamma rays, X-rays, ultraviolet rays, visible light and infrared rays (in order of increasing wavelength. Radiation therapy is an alternative treatment to high intensity focused ultrasound(HIFU) for treatment of prostate cancer. |
Radiation Recall Phenomenon
Radiation recall phenomenon occurs when a site that has been previously irradiated becomes inflamed following the administration of some chemotherapy agents. |
Radiation therapy
| Radiation therapy is the medical use of ionizing radiation as part of cancer treatment to control malignant cells. |
Radical Prostatectomy
| Surgery involving the removal of the entire prostate gland. It is the primary treatment for prostate cancer. |
Radio Allergo Sorbent Testing (RAST)
| Radio Allergo Sorbent Testing (RAST) detects allergen specific IgE in the blood. They are used when skin prick tests (the preferred allergy test) is not suitable or not available. |
Radio Waves
Radio waves are a type of electromagnetic wave that are transmitted at certain frequencies through space (about 3 Hz to 300 GHz). |
Radiofrequency Tumour Ablation
| Radiofrequency tumour ablation acts by using a high frequency alternating current moving from the tip of an electrode into the tissue surrounding the electrode. This will cause the temperature of the tissue in the liver to rise. When the temperature reaches beyond 60 degrees Celsius, the cell begin to die. This is the principle of radiofrequency tumour ablation. |
Radioimmunoassay
A radioimmunoassay was a pregnancy test developed in the 1970s that used a radioactive receptor site containing hCG antibodies to assess a woman's pregnancy status. More about pregnancy tests. |
Radioisotope
| Radioisotope: a form of a chemical element which undergoes spontaneous nuclear disintegration, emitting radiation. |
Radiotherapy
| Radiotherapy involves the use of ionising radiation, either as x-rays or radioactive isotopes, to treat disease. |
Radius
| The radius is a bone of the forearm that extends from the elbow to the thumb side of the wrist of the hand. |
Randomised Controlled Trial
Randomised controlled trials are scientific studies in which participants are assigned to receive different interventions (e.g. diet A and diet B) using a technique known as random allocation. Random allocation ensures that characteristics of the individuals which may influence the effectiveness of the interventions being studied (e.g. body mass index) are distributed evenly between the different groups. |
Rape
| Rape is defined as any sexual act performed by a person(s) on another without consent. It may result from the use of force, the threat of force, or from the victim's inability to give consent. It encompasses all unwanted sexual acts ranging from fondling to penetration. |
Rapid Cycling Bipolar Affective Disorder
| A form of bipolar affective disorder (BPAD) characterised by changes from depression to manic at least 4 times a year and episodes of depression and mania are short. |
Rash
| Breaking out (eruption) of the skin, which can involve changes in texture and colour of skin. |
Raynaud's Phenomenon
| Raynaud's Phenomenon is a disease that is caused by involuntary narrowing of blood vessels most commonly in the regions supplying the fingers, toes, ears and tip of the nose. This can cause death of the tissue in those areas due to lack of blood supply. |
Reactive Biomolecules
Reactive biomolecules are molecules or groups of atoms in the body which are highly reactive, usually because they have free electrons. |
Reandron
| Reandron 1000 contains testosterone. It is used in testosterone replacement therapy in primary and secondary male hypogonadism. |
Recannalisation
| In relation to vasectomy, spontaneous recanalisation refers to the growth of small tubes which link the severed ends of the vas deferens, and thereby create an alternative route via which sperm can travel from the testes to the ejaculatory ducts. |
Receptors
| Receptors are types of proteins that predominantly exist on the surface of cells. There are different receptors for different types of cells. For example, a liver cell will have different receptors than a cardiac cell does. This is important as different receptors bind to different types of proteins and chemicals on the outside of the cell, and this in turn creates a change in the functioning of the cell. |
Recommended Daily Intake (RDI)
| The recommended daily intake (RDI) is the daily dietary intake level of a nutrient that is sufficient to meet the requirements of nearly all (97-98%) healthy individuals in an age and gender-specific group. RDIs are based on the older recommended dietary allowances. |
Recommended Dietary Allowance (RDA)
| The average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (97-98%) healthy individuals in an age and gender-specific group. |
Recreational Drugs
Recreational drugs are drugs taken for recreational purposes. They include marijuana, ecstasy, cocaine and alcohol. Recreational drugs are also known as lifestyle drugs. More about drug abuse (substance abuse). |
Rectal
Rectal means of or pertaining to the rectum. |
Rectum
| The rectum is the end part of the large intestine, where faeces are stored before being released from the intestine during defecation. |
Reductil
| Reductil is used in weight Loss management in conjunction with low calorie diet. |
Reduction Mammoplasty
| Reduction mammoplasty is a cosmetic surgical procedure aimed at reducing macromastia to a comfortable shape and size. |
Referred pain
| Referred pain is pain that originally comes from one organ or part of the body, but is felt in a different place. |
Reflection
| Change in direction of the ultrasound waves at a tissue interface such that the beam does not enter the second tissue. Also known as echo. |
Reflex
| An involuntary, unlearned reaction to a stimulus. Examples of reflexes include sneezing, blinking, gagging, and a knee jerk when the patella tendon is hit with a tendon hammer. |
Refludan (lepirudin)
| Refludan (lepirudin) is an anti-coagulant drug used to treat a complication of heparin therapy called acute heparin-induced thrombocytopaenia (HIT) type II. |
Reflux
Reflux refers to the backward flow of bodily fluids, for example of gastric juices into the oesophagus. For more information, see Gastro-Oesophageal Reflux Disease. |
Refraction
| Refraction refers to the bending of a light ray, and occurs when the ray passes from a medium of one density to another. The greater the difference in densities, the greater the degree of bending and hence refraction. |
Refractory Angina Pectoris
Refractory Angina Pectoris is angina pectoris that still remains after treatment. Angina pectoris is also said to be refractory when patients cannot be treated due to the risks associated with their individual condition. For example they may be allergic to the medication. |
Refractory epilepsy
| Persistant epileptic seizures that occur despite attempted treatment with anti-epileptic medication. |
Refractory pain
| Refractory pain is pain that does not respond to conventional pain treatments, therefore it continues to cause discomfort and distress to the individual. |
Refresh
| Refresh is a lubricating eye drop that soothes dry, tired, sore or irritated eyes. |
Regressive Development
| Regressive development refers to a condition where a child will forget or stop performing an activity previously performed (e.g. a child who commenced walking may stop and return to crawling). |
Rehydration
Rehydration is the replacement of water or electrolytes provided by another fluid after dehydration. Humans become dehydrated after exercise and therefore need to rehydrate themselves during and after physical activity. |
Rejection
| Rejection is a medical complication after transplantation whereby the transplant recipient's body fails to accept the transplanted organ. |
Relapse
| A relapse is the return of a patient's condition after they have recovered. Sometimes they may have only appeared to recover when the disease was still present in their system and therefore minor trigger factors may be the cause of the relapse. Often the symptoms experienced during relapse are worse than the original condition symptoms. |
Relapsed (refractory) disease
| Relapsed or refractory disease refers to cases where you demonstrate a minor response or better to treatment, but then the disease progresses and you relapse, requiring further treatment. It can also refer to cases where your disease progresses within 60 days of your last therapy. |
Relaxation/Mediation Therapy
| Relaxation/Mediation therapy is a type of psychotherapy that can be implemented by a psychologist at the beginning of sessions. The therapist guides the client through a series of visualisation exercises that help the patient to better understand the goals and possibilities of the treatment. There may also be some muscle relaxation through massage or yoga-type activities. |
Relaxin
| Relaxin is a polypeptide hormone secreted by the corpora lutea of mammalian species during pregnancy. Facilitates the birth process by causing a softening and lengthening of the pubic symphysis and cervix; it also inhibits contraction of the uterus and may play a role in timing of parturition. |
Relaxin
| Relaxin is a peptide hormone that has a variety of actions on reproductive and non-reproductive organs. It is mainly produced by the ovary, breast and, during pregnancy, placenta, but other tissues including the prostate and heart are also able to produce and respond to relaxin. As the name suggests, tissues soften, relax or give way upon exposure to relaxin. It softens the reproductive organs and nipples of pregnant women for smooth delivery and milk production. Relaxin also assists in the control of blood volume, kidney function and blood pressure during pregnancy. |
Relenza
Relenza is a drug used in the treatment and prevention of influenza type A and B viruses, including avian influenza and swine flu. The active ingredient in Relenza is zanamivir. For more information, see Relenza. |
REM Sleep (Rapid Eye Movement)
REM sleep is a phase of sleep characterised by rapid eye movement. Vivid dreams that can be recalled are most likely to have occurred during REM sleep. |
Remeron
| Remeron (which contains mirtazapine) is a medication used to treat major depression. |
Remifentanil
Reminyl
| Reminyl is a drug used in the treatment of mild to moderate Alzheimer's disease. |
Renagel
| Renagel is a medication is used to manage hyperphosphataemia, a condition caused by excessive dietary phosphorous being stored in your body as a result of chronic renal disease. |
Renal arteries
| Renal arteries refer to a type of artery which takes blood to the kidneys. |
renal artery stenosis
| Renal Artery Stenosis is a disease of the renal arteries. The name of this condition describes the narrowing (or stenosis) of the main arteries of the kidneys, most often due to accumulation of cholesterol in the affected artery resulting in narrowing and hardening. |
Renal cell carcinoma
| Renal cell carcinoma is cancer of the kidneys. It arises from abnormal cells in the kidney's filtering system. |
Renal failure - acute
| Acute failure of the kidneys is a condition in which there is a rapid loss of the normal function of your kidneys, due to a sudden, acute or chronic insult. |
Renal failure - chronic
| Chronic renal failure is a disease affecting the kidney. Chronic renal failure occurs with long-term kidney disease, resulting in a gradual decline in kidney function over time. |
Renal Function
| If you have two healthy kidneys, you have full renal function. Small declines in renal function are not always a problem, people who suffer from reduced renal function generally do so because of a disease. You will have serious health problems if you have less than 25 percent of your renal function. If your renal function drops below 10 to 15 percent, you cannot live long without some form of renal replacement therapy ; such as dialysis. |
Renal hypertension
| Renal hypertension is high blood pressure due to narrowing of the arteries that carry blood to the kidneys. It is a form of secondary hypertension. |
Renal System
The renal system consists of all the organs involved in the formation and release of urine. It includes the kidneys, ureters, bladder and urethra. The kidneys are bean-shaped organs which help the body produce urine to get rid of unwanted waste substances. When urine is formed, tubes called ureters transport it to the urinary bladder, where it is stored and excreted via the urethra. The kidneys are also important in controlling our blood pressure and producing red blood cells. |
Renin angiotensin system
| Renin angiotensin syetem is a harmonal system that plays a role in the homeostasis of the kidney system. It regulates extracellular fluid and blood pressure in the body. |
Repetitions (reps)
When referring to resistance training the number of repetitions (reps) refers to the number of times a specific resistance exercise is repeated in a set. |
Resistance Training (Weight Training; Strength Training)
Resistance training is a physical activity that involves some form of resistance used against a certain muscle contraction to improve power, strength, flexibility, speed, health, body composition and fitness. There are multiple types of resistance that can be used, including:
For more information, see Resistance Training. |
Resistance welding
Resistance welding is a type of welding process in which an electric arc current is used to join sheets of metal. The electric current is passed between copper electrodes on either side of the metal sheet to achieve the weld. |
Respiratory Distress Syndrome
| Respiratory Distress Syndrome refers to a condition in newborn babies which causes severe difficulty in breathing. It is due to a lack of surfactant production in the newborn. Commonly, respiratory distress syndrome occurs in premature babies who have immature lungs. |
Respiratory System
| The respiratory system consists of all the organs involved in breathing. These include the nose, pharynx, larynx, trachea, bronchi and lungs. The respiratory system has two major functions ensuring the entry of oxygen into our bodies and the removal of carbon dioxide from our bodies. |
Resting Metabolic Rate (RMR)
| The resting metabolic rate (RMR) is the rate in which an individual’s body uses energy in a resting state. A resting state is defined as not during any form of physical exertion. |
Restless Legs Syndrome
| Restless Legs Syndrome (RLS) is a neurological condition whereby the sufferer may feel unpleasant sensations in their legs, compelling them to move. This causes significant disruption to sleep. |
Restorative surgery
| Restorative surgery is used as a follow-up to other surgeries to change or restore the patient's appearance or the function of the related organ/body part, i.e. breast reconstruction surgery is sometimes performed to restore the physical shape of the affected breast(s). |
Retching
| Retching is a strong involuntary effort to vomit, and usually follows nausea. During retching, the abdominal muscles, chest wall and diaphragm all contract without any expulsion of gastric contents. |
Retinal haemorrhage
| Retinal haemorrhage is a disorder of the eye in which bleeding occurs into the retina. |
Retinitis pigmentosa
| Retinitis pigmentosa is a term used to describe a genetic eye condition which is characterized by a gradual loss of the field of vision. This is due to some abnormality affecting the retina. |
Retinoid
| A natural or synthetic substance derived from vitamin A that can be used in the treatment of acne. |
Retractable needle
| A retractable needle automatically retracts into the barrel of the syringe after use. A plunger at the end of the needle must be pushed to engage the safety mechanism, and then pulled back to retract the needle inside. |
Retrograde Ejaculation
A condition in which a man ejaculates into his bladder, meaning that the seminal fluid and the sperm which it contains does not leave the man's body upon orgasm. The condition causes infertility and is often associated with spinal cord injury. More on male reproductive system. More on sperm analysis. |
Retrograde menstruation
| Retrograde menstruation is menstruation in which menstrual blood and waste products enter the fallopian tubes instead of being expelled from the body via the vagina. The condition is though to occur almost universally (i.e. almost all women are thought to experience retrograde menstruation to some extent). |
Retrospective studies
| Retrospective studies are studies that are conducted using data that already exist. This is, the study is not designed to collect data from a planned study but rather to analyse data collected, this could be from a doctor's surgery over a number of years or a hospital admissions log etc. From this information the investigators will try and find significant correlations and patterns in the data. These studies are limited because the variables are not tightly controlled.
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Retrovirus
| A Retrovirus is a class of enveloped virus. Retroviruses contain RNA and utilise an enzyme called reverse transcriptase to translate thier RNA into DNA in the host cell. |
Revascularisation
| Revascularisation is the regrowth of blood vessels following an injury or disease. If revascularisation does not occur naturally it can be done surgically using a blood-vessel graft. The blood supply is re-established for that particular tissue or organ. Coronary revascularisation involves re-establishing the blood supply through the coronary arteries. |
Revatio
Revatio is a cardiovascular agent which is specifically indicated for pulmonary arterial hypertension (high blood pressure in the lungs). |
Reverse Transcriptase
| Reverse Transcriptase is an enzyme produced by retroviruses, such as HIV. Reverse Transcriptase enables retroviruses to synthesize DNA from their viral RNA. |
Reversible Posterior Leucoencephalopathy Syndrome
Reversible posterior leucoencephalopathy syndrome is a reversible brain disorder, characterised by inflammation in the brain. It is caused by hypertension and immune suppression. |
Reye's Syndrome
Reye's syndrome is a condition that can potentially affect all organs of the body; the brain and liver are at the greatest risk of damage. It is associated with the use of aspirin to treat chicken pox or influenza in children. |
RFS - Relapse free survival
| The time to relapse of disease. Relapse may be defined biochemically or clinically. |
Rhabdomyolysis
| Rhabdomyolysis occurs when muscle is damaged and cells are disrupted, the intracellular constituents begin to leak into the blood stream. This includes creatine kinase, myoglobin and the electrolyte potassium. This is termed rhabdomyolysis. This breakdown may be manifested by muscle pain and in extreme cases dark or cola colored urine. |
Rhegmatogenous retinal detachment
| Rhegmatogenous retinal detachment refers to retinal separation associated with a break, a hole, or a tear in the sensory retina. |
Rhesus status
| Rhesus blood group system refers to the five main Rhesus antigens (C, c, D, E and e) on the surface of red blood cells. People who are Rhesus positive have a protein known as D antigen on the surface of their red blood cells, and they are classified as RhD positive. People who do not have the D antigen are known as RhD negative. Your rhesus status is important if you are undergoing an abortion, because if you are RhD negative, you will require further treatment to prevent antibodies from developing in your body. |
rheum
Rheumatoid Arthritis (RA)
| Rheumatoid arthritis (RA) is a disease in which the joints in the body become inflamed. It is the most common form of inflammatory arthritis and is different to osteoarthritis. |
Rhinitis
| Rhinitis means inflammation of the lining of the nose. |
Rhinitis medicamentosa
| Rhinitis medicamentosa is inflammation of the lining of the nose due to the use of intranasal medications. It is characterised by a worsening of symptoms upon cessation of the medication. |
Rhinocort
| Rhinocort is a nasal spray used to treat hayfever and nasal polyps. |
RICE
The term RICE is an acronym that stands for Rest, Ice, Compression and Elevation. Rice is a key management prinicple for muscle and sports injuries. |
Rifamycins
| These include Rifampicin and rifabutin, which are Antibiotics with a strong spectrum of activity against Gram positive organisms and mycobacteria. Mycobacteria are those bacteria that can cause diseases such as tuberculosis, chest infections, infection of lymph nodes (lymphadenitis) |
Riga-Fedes syndrome
| Riga-Fedes syndrome, essentially is the occurrence of ulceration and infant discomfort due to the eruption of the primary teeth. |
Risk Factor
Risk factors are components that increase your risk of developing a specific disease and/or condition (e.g. cardiovascular risk factors for the development of heart disease). |
Risperdal
| Risperdal is a drug that belongs to a class known as 'atypical antipsychotic'. Risperdal acts on numerous different chemical signals within the brain to change the chemical balance around these receptors. |
Risperdal Consta
| Risperdal Consta is a drug that belongs to a class known as 'atypical antipsychotics'. It is called this because it is a newer class of drugs than the older antipsychotic agents and has a lower risk of certain adverse effects. It is used for the treatment of schizophrenia and related psychoses. |
Ritonavir
| Ritonavir is an anti-HIV drug from the class of protease inhibitors. Nowadays, it is more common to see ritonavir prescribed together with other anti-HIV drugs as a booster. |
RNA
| RNA stands for ribonucleic acid. It is found in cell and helps in the production of proteins. RNA takes the instructions for the making of proteins from the DNA to the site where the protein is manufactured. RNA is similar to DNA but is single-stranded as opposed to double-stranded and RNA strands are also much shorter than DNA. |
Robotic Radical Prostatectomy
| A type of Robotic Prostate surgery that includes the laparoscopic surgical removal of the prostate gland using a highly advanced robotic system. The robot is controlled by a surgeon via a nearby computer console. |
Root
| Root refers to the part of a tooth that is hidden in the gum. The root of the tooth functions as an anchor for the tooth and allows for blood and nerve supply to enter the tooth to maintain its viability. |
Root canal
| A root canal is a dental procedure in which a hole is drilled into the decayed tooth, cleaned and filled with medicine, and capped with a crown. |
Root injury
The root is the nerve fibres that emerge from the spinal cord in a bundle. When this area is damaged the individual is left with a very painful condition known as root injury. |
Ropivacaine
| Ropivacaine is a local anaesthetic that stabilises the neuronal membrane and prevents the initiation and transmission of nerve impulses. It also has both anaesthetic and analgesic effects. At higher doses it produces surgical anaesthesia with motor block, while at lower doses it produces a sensory block, including analgesia, with little motor block. |
Rosacea
| Rosacea is an inflammatory skin disorder which causes excessive facial redness. It often appears as red or pink patches, visible broken blood vessels and small red bumps on the skin surface across the central part of the face. It is most common in women aged between 30-60 years. |
Rosiglitazone
| Rosiglitazone is a medication used in the treatment of type 2 diabetes mellitus. Type 2 diabetes mellitus is characterised by insulin resistance. Rosiglitazone works by making the body more sensitive to insulin, especially the liver, skeletal muscle and adipose tissue. Avandia also helps to improve glucose metabolism by lowering blood glucose, circulating insulin and free fatty acids. |
Rotator Cuff Injury
| The rotator cuff is a group of muscles which together, help to control the shoulder joint during rotation. Problems with the rotator cuff muscles can be classed into two categories;
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Rotavirus
| Rotavirus is the most common virus that causes viral gastroenteritis. |
Rotor syndrome
| Rotor syndrome refers to an inherited syndrome in which the liver can not adequately excrete bilirubin. |
Round window
| The round window separates the scala tympani from the middle ear. It vibrates in unison with fluid movements in perilymph to dissipate pressure. It does not contribute to sound reception. |
RR - Response rate
| The percentage of patients with a complete response (CR) or partial response (PR). |
Rubella
| Rubella (German measles) is a viral illness which may produce a rash, swollen glands, joint pain and muscle pains in infected children or adults. Though most infections are mild, the real danger of rubella infection lies in the risk of Congenital Rubella Syndrome, which may occur if a non-immune pregnant woman becomes infected during the first half of pregnancy. This can have devastating consequences for the baby, which may be born deaf, blind, with heart defects, or mentally retarded. Children and adults can be protected against rubella infection through immunisation. |
