Webster's New World Medical Dictionary

hyperplasia, benign prostatic
See 
benign
prostatic hyperplasia.
hyperplasia, endometrial
A condition charac-
terized by overgrowth of the lining of the uterus.
This is considered a precancerous condition.
hypersomnia
Excessive sleepiness in which a
person has trouble staying awake during the day or
exhibits prolonged nighttime sleep. People who
have hypersomnia can fall asleep at any time—for
example, at work or while they are driving—and
they may have other sleep-related problems. Causes
include narcolepsy, sleep deprivation, neurological
or other medical conditions, obesity, genetic fac-
tors, medications, and drug or alcohol abuse.
hypertension
See 
high blood pressure.
hypertension, benign intracranial
See
pseudotumor cerebri.
hypertension, pulmonary
High blood pressure
in the pulmonary arteries. This elevated blood pres-
sure can lead to severe shortness of breath and
death. Lung transplantation is considered in severe
cases that are unresponsive to treatments. 
hyperthermia
Overheating of the body, possibly
due to extreme weather conditions. Unrelieved
hyperthermia can lead to collapse and death, partic-
ularly in the elderly. Hyperthermia can be prevented
in many cases through use of air conditioning and
ventilation, as well as by ensuring that vulnerable
persons drink extra water. In emergency cases of
hyperthermia, injections of saline solution and rapid
cooling of the body may be necessary. Also known as
heatstroke and heat prostration.
hyperthermia, malignant
A rare inherited dis-
ease that causes a rapid rise in body temperature
and muscle rigidity when a person undergoes gen-
eral anesthesia. Succinyl choline and halothane are
the two drugs most associated with the condition.
The result can be destruction of muscle tissue, kid-
ney failure, and death may occur. The propensity to
malignant hyperthermia is inherited in an autoso-
mal dominant manner. One form of malignant
hyperthermia is produced by mutation of the ryan-
odine receptor gene (RYR1). Treatment involves
administration of dantrolene sodium (brand name:
Dantrium) and rapid cooling of the patient.
hyperthyroid
Having an excessive amount of thy-
roid hormone resulting from an overactive thyroid
gland or from taking too much thyroid hormone.
Symptoms of hyperthyroidism can include
increased heart rate, weight loss, depression, and
cognitive slowing. Treatment can include medica-
tions, the use of radioactive iodine, thyroid surgery,
or a reduction in the dose of thyroid hormone.
hypertonia
Increased tightness of muscle tone
and reduced capacity of the muscle to stretch
caused by damage to the motor nerve pathways in
the central nervous system. Untreated hypertonia
can lead to loss of function and deformity.
Treatment can include physical and/or occupational
therapy or medications. Injections of botulism toxin
(botox) are sometimes used in the treatment for
chronic hypertonia in cerebral palsy and other dis-
orders. Also known as spasticity.