LUNG FUNCTION TESTS
LUTEINIZING HORMONE
cystic fibrosis.
The lungs can also be
affected by allergic disorders. The most
important of these is
asthma.
Another
such disorder is allergic
alveolitis,
which
is usually a reaction to dust of plant or
animal origin. Irritation of the airways,
usually by tobacco-
smoking,
can cause
diseases characterized by damage to
lung tissue and narrowing of the airways
(see
pulmonary disease, chronic obstruc-
tive
). The lungs can also be affected by
cancerous tumours;
lung cancer
is one
of the most common cancers. Non-
cancerous lung tumours are uncommon.
Injury to a lung, usually resulting from
penetration of the chest wall, can cause
the lung to collapse (see
pneumothorax;
haemothorax).
Damage to the interior of
the lungs can be caused by inhalation
of toxic substances (see
asbestosis
;
sili-
cosis). Blood supply to the lungs may be
reduced by
pulmonary em bolism
.
Lung disorders can be investigated in
various ways, such as
chest X-ray, bron-
choscopy,
and
pulmonary function tests.
lung function tests
See
pulmonary func-
tion tests
.
lung imaging
Techniques that provide
images of the
lungs
to aid in the diag-
nosis of disease. Most
lung disorders
can be detected by
chest X-ray. CT scan-
ning
and
MRI
play an important role in
detecting the presence and spread of
lung tumours. Utrasound scanning
is
sometimes used to reveal
pleural effu-
sion. Radioisotope scanning
is used to
detect evidence of pulmonary embolism.
lung tumours
Growths in the lungs.
These tumours may be either cancerous
(see
lung cancer
) or noncancerous.
Cancerous lung tumours are usually
associated with tobacco-
smoking
. Non-
cancerous tumours occur less frequently
than cancers. The most common form
of noncancerous tumour is a bronchial
adenom a
, which arises in the lining of a
bronchus
. Adenomas often cause bron-
chial obstruction; affected people may
also cough up blood. Treatment involves
surgical removal of the tumour. Other
rare noncancerous tumours include
fib-
romas
(which consist of fibrous tissue)
and
lipomas
(which consist of fatty tis-
sue). No treatment is necessary unless
the tumours are causing problems.
lupus erythematosus
An
autoimmune
disorder
that causes inflammation of
connective tissue.
The most common
type, discoid lupus erythematosus (DLE),
only affects exposed areas of the skin.
The more serious form,
systemic lupus
erythematosus
(SLE), affects many body
systems, including the skin.
In both varieties of lupus erythemato-
sus, the symptoms periodically subside
and recur with varying severity. In DLE,
the rash starts as one or more red, cir-
cular, thickened areas of skin that later
scar. These patches may occur on the
face, behind the ears, and on the scalp.
Treatment is usually with topical
corti-
costeroid drugs.
SLE causes a variety of
symptoms. A characteristic red, blotchy,
butterfly-shaped rash may appear over
the cheeks and the bridge of the nose;
other symptoms include fatigue, fever,
loss of appetite, nausea, joint pain, and
weight loss. There may also be
anaemia
,
neurological or psychiatric problems,
kidney failure
,
pleurisy
, arthritis, and
pericarditis
. Diagnosis is made by
blood
tests
and sometimes a
skin biopsy
.
Sufferers of mild forms of SLE may
have near normal health for many years;
treatment with
corticosteroid drugs
and
immunosuppressant drugs
can improve
life expectancy. Other treatments are
available to treat specific features of the
disease. However, SLE is still a poten-
tially fatal disorder.
lupus pernio
Sarcoidosis
affecting the
skin, in which purple, chilblain-like swell-
ings appear on the nose, cheeks, or ears.
lupus vulgaris
A rare form of
tubercu-
losis
affecting the skin, especially on the
head and neck. Painless, clear, red-brown
nodules appear and ulcerate; the ulcers
eventually heal, leaving deep scars.
luteinizing hormone
Also known as
LH, a
gonadotrophin horm one
produced
by the
pituitary gland
.
luteinizing hormone-releasing hor-
mone
A naturally occurring
horm one
,
also known as LH-RH, that is released
by the
hypothalamus
in the brain. This
hormone is also prepared synthetically
as a drug. Natural LH-RH stimulates
the release of
gonadotrophin horm ones
from the
pituitary gland.
Gonadotrophin
hormones control the production of
348
previous page 346 BMA Illustrated Medical Dictionary read online next page 348 BMA Illustrated Medical Dictionary read online Home Toggle text on/off