limpAn abnormal pattern of walkingin
which the movements of one leg (or of
the hipon one side of the body) are dif-
ferent from those of the other. A limp in
a child should always be seen within 24
hours as it may result from a hip prob-
lem that requires treatment.
linctusA bland, usually sweetened mix-
ture taken to soothe irritation caused
by an inflamed throat. A simple linctus
contains no active drug, but linctuses
are commonly used as a basis for cough
suppressants (see cough remedies).
lindaneA drug formerly used to treat
infestation by scabiesand some types of
lice. Lindane has now been replaced by
other, less toxic drugs.
linear acceleratorA device for accel-
erating subatomic particles, such as
electrons, to a speed approaching that
of light so that they have extremely high
energies. A linear accelerator can also
be used to generate high-energy X-rays.
High-energy electrons or X-rays are used
in radiotherapyto treat certain cancers.
linimentA liquid rubbed on the skin to
relieve aching muscles and stiff joints.
Liniments may contain rubefacients
(substances that increase blood flow be-
neath the skin), or certain drugs, such
as nonsteroidal anti-inflammatory drugs.
liothyronine A thyroid hormoneused as
replacement therapy in hypothyroidism.
Liothyronine acts more quickly than
levothyroxineand is cleared from the
body more rapidly.
lipOne of 2 fleshy folds around the
entrance to the mouth. The main sub-
structure of the lips is a ring of muscle
that helps to produce speech. Smaller
muscles at the corners of the lips are
responsible for facial expression. Disor-
ders of the lips include chapped skin,
cheilitis, cold sores, and lip cancer.
lip cancerA malignanttumour, usually
on the lower lip. Lip cancer is largely
confined to older people, particularly
those who have been exposed to a lot
of sunlight and those who have smoked
cigarettes or a pipe for many years. The
first symptom is a white patch that
develops on the lip and soon becomes
scaly and cracked with a yellow crust.
The affected area grows and eventually
becomes ulcerated. In some cases, the
cancer spreads to the lymph nodesin
the jaw and neck. Lip cancer (usually a
squamous cell carcinoma) is diagnosed
by biopsy. Treatment is surgical removal,
radiotherapy, or a combination of both.
lipectomy, suctionA type of body con-
tour surgeryin which excess fat is
sucked out through a small skin incision.
lipid disordersMetabolic disorders that
result in abnormal amounts of lipids(fats)
in the body. The most common lipid dis-
orders are the hyperlipidaemias, which
are characterized by high levels of lipids
in the blood and can cause atheroscle-
rosisand pancreatitis. There are also
some very rare lipid disorders due solely
to heredity, such as Tay–Sachs disease.
lipid-lowering drugsA group of drugs
used to treat hyperlipidaemia. These
drugs help to prevent, or slow the pro-
gression of, severe atherosclerosisand
coronary artery disease. The most com-
monly used types are statinsand fibrates.
lipidsA general term for fats and oils.
Lipids include triglycerides (simple fats),
phospholipids (important constituents
of cell membranes and nerve tissue),
and sterols, such as cholesterol.
lipomaA common noncancerous tumour
of fatty tissue. Lipomas are slow-growing,
soft swellings that may occur anywhere
on the body, most commonly on the
thigh, trunk, or shoulder. They are pain-
less and harmless, but may be surgically
removed for cosmetic reasons.
lipoproteinParticles comprising a fatty
core and protein outer layer (apolipro-
tein) that allow the transport of fats in
the bloodstream. Genetic variations in
the structure of apoliproteins and lipo-
proteins play an important part in
determining susceptibility to cardiovas-
cular disordersand Alzheimer’s disease.
liposarcomaA rare cancer of fatty tissue
that most commonly develops during
late middle age. Liposarcomas produce
firm swellings, usually in the abdomen
or the thigh. The tumours can generally
be removed by surgery but tend to recur.
liposuctionThe popular term for suc-
tion lipectomy (see lipectomy, suction).
lip-readingA way of understanding
speech by interpreting movements of
the mouth and tongue. Lip-reading is
often used by people who are deaf.LIMP LIP-READING
L