DIURNAL RHYTHMS
DIZZINESS
D
Diuretic drugs may cause chemical
imbalances in the blood. Hypokalaemia
(low blood levels of potassium) is usually
treated with potassium supplements or
potassium-sparing diuretic drugs. A diet
rich in potassium may be helpful. Some
diuretics raise the blood level of uric acid,
increasing the risk of
gout.
Certain diuret-
ics increase the blood glucose level, which
can cause or worsen
diabetes mellitus.
diurnal rhythms
A biological pattern
based on a daily cycle; also called
circa-
dian rhythms.
(See also
biorhythms.)
diverticula
Small sacs or pouches that
protrude externally from the wall of a
hollow organ (such as the colon). They
are thought to be caused by pressure
forcing the lining of the organ though
areas of weakness in the wall. Their
presence in the walls of the intestines is
characteristic of
diverticular disease.
diverticular disease
The presence of
small protruding sacs or pouches called
diverticula, in the wall of the intestines,
and the symptoms or complications
caused by them. The term
diverticulosis
signifies the presence of diverticula in
the intestine.
Diverticulitis
is a compli-
cation produced by inflammation in
1
or more diverticula.
diverticulitis
Inflammation of
divertic-
ula
in the intestine, particularly in the
colon.
It is a form of
diverticular disease
and a complication of
diverticulosis
.
Diverticula may perforate and abscess-
es may form in the tissue around the
colon, leading to
peritonitis.
Other com-
plications include intestinal bleeding,
narrowing in the intestine, or a
fistula.
Symptoms include fever, abdominal
pain, vomiting, and rigidity of the abdo-
men. Intestinal haemorrhage may cause
bleeding from the rectum. Diverticulitis
usually subsides with bed rest and
anti-
biotics
. In severe cases, a liquid diet or
intravenous infusion
may be required.
Surgery may be needed, in which case,
the diseased section of the intestine is
usually removed and the remaining sec-
tions are joined together. Some patients
are given a temporary
colostomy
.
diverticulosis
A form of
diverticular
disease
in which there are
diverticula
present in the intestine, particularly in
the
colon.
Complications of diverticulosis
may include intestinal bleeding and
diverticulitis
.
The cause is believed to be
lack of adequate dietary fibre (see
fibre,
dietary
). Diverticulosis is very rare in
developing countries.
Symptoms occur in only 20 per cent
of people with diverticulosis. They usu-
ally result from spasm or cramp of the
intestinal muscle near diverticula. Many
patients
have
symptoms similar to
those of
irritable bowel syndrome
,
such
as abdominal pain, a bloated sensation,
and changes in bowel habits. In severe
cases, intestinal haemorrhage may pro-
duce bleeding from the rectum.
In patients with cramps, a high-fibre
diet, fibre supplements, and
antispas-
modic drugs
may relieve the symptoms.
A high-fibre diet also reduces the inci-
dence of complications. Bleeding from
diverticula usually subsides without
treatment, but surgery is an option.
diving medicine
See
scuba-diving medi-
cine
;
decompression sickness
.
dizziness
A sensation of unsteadiness
and light-headedness. It may be a mild,
brief symptom that occurs by itself, or it
may be part of a more severe, pro-
longed attack of
vertigo
with nausea,
vomiting, sweating, or fainting.
Most attacks are harmless and are
caused by a fall in the pressure of blood
to the brain. This can occur when get-
ting up quickly from a sitting or lying
position (called
postural hypotension
).
Similar symptoms may result from a
transient ischaemic attack,
in
which
there is temporary, partial blockage in
the arteries that supply the brain. Other
causes include tiredness, stress, fever,
anaemia
,
heart block
,
hypoglycaemia
,
and
subdural haemorrhage
.
Dizziness as part of vertigo is usually
due to a disorder of the inner ear, the
acoustic nerve
,
or the
brainstem
.
The
principal disorders of the inner ear that
can cause dizziness and vertigo are
labyrinthitis
and
Meniere's disease
.
Dis-
orders of the acoustic nerve, such as
acoustic neuroma
, are rare causes of
dizziness and vertigo. Brainstem disor-
ders which can cause dizziness and
vertigo include a type of
migraine
,
brain
tumours
, and
vertebrobasilar insufficiency
.
Brief episodes of mild dizziness usually
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