CYSTINURIA
The juvenile form of cystinosis be-
comes apparent in the first year of life,
at w hich time cystine deposits damage
the eyes, resulting in impaired vision.
The deposits also lead to potentially
fatal
kidney failure
.
In the
adult form, w hich is
less
severe,
the main symptoms
are
eye
problems, including extreme sensitivity
to light (see
photophobia
) .
The kidneys
are much less likely to be affected in
adults than in children.
cystinuria
An inherited disorder (see
metabolism,
inborn errors of
) in w hich the kidneys
are unable effectively to process certain
amino acids
(the chemical compounds
that make up proteins). Cystinuria is
inherited in an
autosomal
recessive
manner
(see
genetic disorders
)
and
occurs in around one in
1,000
births.
Under normal circumstances, blood
is filtered as it passes through the
kid-
neys
;
a wide range of substances is
removed, then useful compounds, such
as
amino
acids,
are
reabsorbed.
In
cystinuria, this process does not work
effectively. As a result, high levels of
four amino acids, particularly cystine,
occur in the urine. This excess cystine
can result in the development of a rare
form of kidney stones (see
renal calculi
)
in both adults and children.
Cystinuria is usually detected in peo-
ple w ho
have symptoms
of kidney
stones, or in those who have passed
stones that, on analysis, are found to
contain cystine. The diagnosis can be
confirmed by urine tests that measure
the levels of amino acids. Treatment
involves drinking large amounts of flu-
ids regularly in order to dilute the
urine and reduce the concentration of
cystine. If the levels of cysteine remain
high, the drug
penicillamine
may be
required to help prevent the formation
of new stones.
cystitis
Inflammation of the lining of the
blad-
der
that
is
usually
the
result
of a
bacterial infection.
CAUSES
Cystitis is more common in women
than men because the
urethra
is short,
so it is relatively easier for the bacteria
that cause the disorder to pass into the
bladder. A bladder
calculus
(stone), a
bladder tumour,
or a
urethral stricture
can
obstruct urine flow and increase the
risk of infection. In men, cystitis is
rare;
it
usually
occurs
when
an
obstruction, such as an enlarged pro-
state
gland
(see
prostate,
enlarged
),
compresses
the
urethra.
Cystitis
in
children is
often
associated w ith a
structural abnormality of the
ureters
,
w hich allows
reflux
(backward flow) of
urine towards the kidneys.
The use of catheters (see
catheteriza-
tion, urinary
)
also carries the risk of
infection. People w ith
diabetes mellitus
are
especially susceptible to urinary
tract infections because they have high-
er-than-normal
levels
of glucose
in
their
urine
w hich
encourages
the
growth of bacteria.
SYMPTOMS
The main symptoms are a frequent urge
to pass
urine
and a burning pain on u ri-
nating. The urine may be foul-smelling
or may contain blood. There may also be
fever and chills, and lower abdominal
discomfort. However, in children there
are frequently no symptoms relating to
the urinary tract, and they may have
only
generalized symptoms,
such
as
fever and vomiting.
TREATMENT
Symptoms
of m ild
cystitis
may
be
relieved by drinking 0.5 litre of fluid
every four hours, w hich helps to flush
out the bladder. Any bacterial infection
is treated with
antibiotic drugs
to prevent
bacteria from spreading upwards to the
kidneys
and
causing
pyelonephritis
(infection of the kidneys).
cystocele
A swelling in the front of the
vagina
that forms where the
bladder
pushes
against weakened tissues in the vaginal
wall.
A cystocele
may
be
associated
with a prolapsed uterus
(see
uterus,
prolapse of).
Occasionally, a cystocele
may pull the urethra out of position,
causing
stress incontinence
or incom -
plete emptying of the bladder, w hich
may lead to infection of the retained
urine (see
cystitis
).
Pelvic floor exercises
may
help
to
relieve symptoms. Surgery may be per-
formed to lift and tighten the tissues at
the front of the vagina.
cystometry
A procedure that is used to assess the
function of the
bladder
and also to
investigate urinary
incontinence
or poor
bladder emptying; it is also used to
detect abnormalities of the
nerves
sup-
plying the bladder. In this procedure, a
catheter is inserted into the bladder,
then the internal pressure is measured
as the bladder is filled and then emp-
tied. (See
urodynamics.)
cystoscopy
The examination of the
urethra
and
bladder
using a cystoscope inserted up
the urethra. A cystoscope is a viewing
instrument, w hich can be rigid or flex-
ible, sometimes w ith a camera at the
tip (see
endoscopy
).
PROCEDURE FOR CYSTOSCOPY
Cystoscopy involves passing a viewing instrument (cystoscope) up the urethra and
into the bladder under local or general anaesthesia. There is no risk of damage to
the genital organs or urinary tract, although the patient may feel some discomfort
when passing urine for the first few days afterwards.
View through
cystoscope
E y e p i e c e .
CYSTOSCOPE
S h e a t h
F o r c e p s
210
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