Any substance involved in a
metabolic reaction (a biochemical reac-
tion in the body). The term metabolite
is sometimes used to refer only to the
products of a metabolic reaction. (See
One of 5 long, cylin-
drical bones within the hand. The bones
run from the wrist to the base of each
digit, with the heads of the bones form-
ing the knuckles.
A change in tissue resulting
from the transformation of one type of
cell into another. Usually harmless, but
occasionally precancerous, metaplasia
can affect the lining of various organs,
such as the bronchi (airways) and blad-
der. Metaplasia of the cervix, which
, can be detec-
ted by a
cervical smear test
A secondary cancerous tu-
mour (one that has spread from a
to another part of the
body). The term also applies to the pro-
cess by which such spread occurs.
Metastases can spread through the lym-
phatic system, in the bloodstream, or
across a body cavity.
One of 5 long, cylin-
drical bones within the foot. The bones
make up the central skeleton of the foot
and are held in an arch by the surround-
Pain in the foot. Causes
include fracture of a
of a nerve in the foot.
adjoining toe bone (see
metatarsophalangeal joint at the base
of the big toe is commonly affected by
An oral hypoglycaemic drug
) that lowers
blood glucose levels and is used to
treat type 2
adverse effects include loss of appetite, a
metallic taste in the mouth, nausea,
vomiting, and diarrhoea.
A synthetic opioid
that resembles morphine.
Methadone is used under supervision
to relieve withdrawal symptoms in peo-
ple undergoing a heroin or morphine
detoxification programme. Side effects
may include nausea, vomiting, consti-
pation, dizziness, and dry mouth.
A colourless, odourless, highly
inflammable gas that occurs naturally
in oil wells and coal mines. Methane is
also produced by the decomposition of
organic matter; it is one of the gases
present in intestinal gas (see
A poisonous type of
that is used as a solvent or paint re-
mover and in some types of antifreeze.
Methanol poisoning usually occurs as a
result of drinking it as a substitute for
ordinary alcohol. Symptoms of poison-
ing include headache, dizziness, nausea,
vomiting, and unconsciousness. Dam-
age may also occur to the
, causing blurred vision. Re-
peated or large doses of methanol may
result in permanent blindness.
(cancer of the lymph
nodes) and some forms of
Methotrexate is also used to treat can-
cers of the uterus, breast, ovary, lung,
bladder, and testis, and severe
when other treatments are ineffective.
Methotrexate may cause nausea, vomit-
ing, diarrhoea, mouth ulcers,
increased susceptibility to infection,
and abnormal bleeding.
An alternative name
used to treat
Methylcellulose increases the firmness
of faeces in chronic watery
and regulates their consistency in peo-
ple who have a
It is also given as eyedrops to relieve
dry eyes. As methylcellulose causes a
feeling of fullness, it is sometimes used
to help treat
depression, and nasal congestion.
used, under spe-
cialist supervision, to treat
deficit hyperactivity disorder (ADHD)