Health A-Z

Rebound Headache

Clinical Definition Rebound headaches are the escalation of headache pain after the discontinuation of analgesics. Rebound headaches often occur frequently, even daily. The exact physiology of what causes rebound headaches is not completely understood. It is theorized that headache medication may alter or interfere with a particular individual’s brain chemistry and affect how pain pathways

Renal Failure

Clinical Definition Renal failure is either a level of glomerular filtration rate of less than 15 mL/min/1.73m2, or a need to initiate kidney replacement therapy, either dialysis or transplantation, for complications of decreased GFR.  GRF levels used in defining renal failure are viewed as arbitrary in potential need of modification based on kidney replacement therapy

Respiratory infection

Clinical Definition A respiratory infection is considered an infectious disease, such as pneumonia, influenza and the common cold, which affects the respiratory tract. Respiratory infections may affect the upper respiratory tract, lower respiratory tract, or both.  A respiratory infection may be caused by a viral or bacterial pathogen and may range from mild to severe.

Respiratory Syncytial Virus

Clinical Definition Respiratory syncytial virus is an infection caused by the virus from the Pneumovirus genus. Although healthy adults can become infected, it usually results in a mild respiratory infection. In young children, it tends to cause inflammation of the bronchioles. In some cases, it may also lead to bronchopneumonia and respiratory failure. The infection

Restless legs syndrome

Clinical Definition Restless legs syndrome is a neurological disorder characterized by intense urges to move the legs, typically in supine positions and accompanied by uncomfortable periodic prickling sensations. Exact cause is unknown, but several underlying conditions are thought to be associated with restless leg syndrome, including iron deficiency, kidney failure and peripheral nerve disease. In


Clinical Definition Rett syndrome is a pediatric neurodevelopmental disorder predominantly affecting females.  The nervous system disorder leads to developmental reversals, especially in expressive language and use of the hands. Breathing problems, floppy limbs and seizures may occur In Our Own Words Rett syndrome is a genetic disorder affecting the nervous system. The gene thought to


Clinical Definition Reyes syndrome is a rare, acute illness that produces a buildup of fat in the body’s organ systems. It primarily causes encephalopathy and brain damage, along with fatty degenerative liver failure. Typically, it affects children under the age of 15. The specific cause is not known, but an association with ingestion of salicylates

View Terms Beginning with "S"