Bma Illustrated Medical Dictionary

continuously for 24 hours or longer. The

monitor records by means of electrodes

attached to the chest and allows the

detection of intermittent arrhythmias.

homeopathyA system of complementary

medicine.Homeopathy involves admin-

istering minute doses of medicines

which, in a healthy person, would be

capable of inducing symptoms of the

condition that is being treated.

homeostasisThe automatic processes

by which the body maintains a constant

internal environment despite external

changes. Homeostasis regulates condi-

tions such as temperature and acidity by

negative feedback. For example, when the

body overheats, sweatingis stimulated

until the temperature returns to normal.

Homeostasis also involves the regulation

of blood pressureand blood glucose levels.

homocystinuriaA rare, inherited con-

dition caused by an enzymedeficiency.

Homocystinuria is a type of inborn error

of metabolism (see metabolism, inborn

errors of) in which there is an abnormal

presence of homocystine (an amino

acid) in the blood and urine. Affected

people are very tall, with long limbs and

fingers. Some have skeletal deformities

and abnormalities of the eye lens. The

condition is incurable but may be

improved by a special diet.

homosexualitySexual attraction to peo-

ple of the same sex. (See also bisexuality;

heterosexuality.)

homozygoteA term used to describe a

person whose cells contain 2 identical

allelescontrolling a specified inherited

trait. The cells of a heterozygote contain

HOLTER MONITOR
or constant dripping of mucus from the
nasal passages. Polypson the vocal cords
may also cause hoarseness. In people
with hypothyroidism, hoarseness can
result from formation of tissue on the
vocal cords. In young children, hoarse-
ness may be a symptom of croup.
Occasionally persistent hoarseness in
adults has a more serious cause, such
as cancer of the larynx (see larynx, can-
cer of), thyroid cancer, or lung cancer.
Resting the voice helps in strain- or
laryngitis- related cases. If hoarseness
persists for more than 2 weeks, a doctor
should be consulted. A laryngoscopy
may be performed to exclude a serious
underlying cause.
Hodgkin’s diseaseAn uncommon, can-
cerous disorder in which there is a
proliferation of cells in the lymphoid
tissue (found mainly in the lymph nodes
and spleen). Men are affected more than
women. The cause is unknown.
The most common sign is the painless
enlargement of lymph nodes, typically
in the neck or armpits. There may be a
general feeling of illness, with fever,
weight loss, and night sweats. There
may also be generalized itching. As the
disease progresses, the immune system
becomes increasingly impaired and life-
threatening complications may result
from normally trivial infections.
Diagnosis of Hodgkin’s disease depends
on the identification of characteristic cells
in a biopsyof affected tissue. The extent
of the disease (its stage) can be assessed
by chest X-ray, CT scanningor MRIof
the abdomen, a bone marrow biopsyand
a liver biopsy. If the disease is localized
to a small area, radiotherapyis usually
curative. If the disease has spread to
involve many organs, long-term treat-
ment with anticancer drugsis needed.
(See also lymphoma, non-Hodgkin’s.)
hole in the heartThe common name
for a septal defect.
holistic medicineA form of therapy
that treats the whole person, not just
specific disease symptoms. A holistic
approach is emphasized by many prac-
titioners of complementary medicine.
Holter monitorA wearable device used
in ambulatory electrocardiography(ECG)
to record the heart’s electrical activity

HODGKIN’S DISEASE HOMOZYGOTE

Shoulder

strap

Electrode

Holter

monitor

H