MACRO-
MALABSORPTION
macro-
A prefix meaning large, as in
macrophage (a large cell in the
immune
system
)
or
macroglossia
.
macrobiotics
A dietary system in which
foods with a balance of
yin and yang
are eaten. Foods are classified as yin or
yang depending on factors such as
their colour, texture, and taste.
macroglossia
Abnormal enlargement of
the tongue. Macroglossia is a feature
of
Down's syndrome
,
hypothyroidism
,
and
acromegaly
. It is also caused by
some tumours of the tongue, such as a
haemangioma
or a
lymphangioma
.
macrolide drugs
A class of
antibiotic
drugs
used to treat a wide range of infec-
tions including those of the ear, nose,
throat, respiratory and gastrointestinal
tracts, and skin. Common macrolides
include
azithromycin
and
erythromycin
.
macrophage
A cell in the
immune sys-
tem
.
Macrophages are large
phagocytes
,
which can engulf and destroy micro-
organisms and other foreign particles.
They are found in most body tissues.
macula
The area of the eye's
retina
responsible for seeing fine detail. The
macula surrounds the
fovea
,
which con-
tains the highest density of visual cells.
macular degeneration
A progressive,
painless disorder affecting the
macula
.
The result is a roughly circular area of
blindness that increases in size until it
is large enough to obscure 2 or 3 words
at reading distance. Macular degenera-
tion does not cause total blindness as
vision is retained around the edges of
the visual fields. This condition is a
common disorder in elderly people.
Of the 2 types of macular degenera-
tion that may occur, one type is usually
remedied by
laser treatment
. There is no
treatment for the other form, although
the affected person may benefit from
aids such as magnifying instruments.
macule
A spot that is level with the
skin's surface and discernible only by
difference in colour or texture.
mad cow disease
The commonly used
name for
bovine spongiform enceph-
alopathy
(BSE).
magnesium
An element essential in
the diet for the formation of bones and
teeth, muscle contraction, nerve impulse
transmission, and activation of many
enzymes.
Dietary sources include cere-
als, nuts, soya beans, milk, and fish.
magnesium
sulphate
A magnesium
compound used as a
laxative drug
and
an
anticonvulsant drug
.
magnesium trisilicate
A magnesium
compound used in
antacid drugs.
magnetic
resonance
imaging
See
MRI.
malabsorption
Impaired absorption of
nutrients by the lining of the small
intestine. Malabsorption may be caused
by many conditions, including
lactase
deficiency
,
cystic fibrosis
, chronic
pan-
creatitis, coeliac disease, Crohn's disease,
amyloidosis, giardiasis, Whipple's dis-
ease,
and
lymphoma.
The removal of
some of the small intestine, and certain
operations on the stomach, may also
result in malabsorption.
Common symptoms are diarrhoea and
weight loss; and in severe cases, there
may also be malnutrition (see
nutritional
disorders
),
vitamin
deficiency,
mineral
deficiency, or
anaemia
. Diagnosis may
be made by tests on faeces,
blood tests,
barium X-ray examination
and
jejunal
biopsy
. In most cases, dietary modifica-
tions or supplements are successful in
352
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