0631 ser kidney book d
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A GUIDE FOR PATIENTS
48
THE KIDNEYCysts in the kidney and polycystic kidney disease
Cysts in the kidneys
Cysts are fluid-filled structures within or on the edge of the kidney. They are
nearly always a coincidental finding on ultrasound, but occasionally they may
cause pain and tenderness. Rarely, they may bleed, become infected or
if very large, may cause pressure on the surrounding organs such as the
large intestine.
If a cyst is detected an expert ultrasound review should be made to
determine the shape, contents and wall structure of the cyst which might
indicate it is not a simple cyst but something more serious such as an
inherited cystic disorder of the kidneys or, rarely, a cystic tumour of
the kidney.
In patients over 50 years of age, 50% have one or more simple cysts,
which usually do not cause symptoms or long-term problems.
Polycystic kidney disease
Autosomal dominant polycystic kidney disease (ADPKD)
ADPKD is an inherited cystic disorder of the kidney in which multiple
cysts form in the kidneys and progressively increase in size, compressing
adjacent kidney tissue. When severe, this may ultimately lead to end stage
kidney failure.
Who is at risk of developing ADPKD?
In this condition, half of the children born to people with ADPKD will
carry the gene, some of whom will eventually develop kidney failure.
Recent discoveries now allow us to identify in advance who carries the
gene, however no way has yet been devised to predict who will develop
end-stage kidney failure. For those offspring who do develop kidney failure,
it occurs at an average age of 50–60 years, but it may happen much earlier
or much later. In about 10% of affected families the disease occurs later and
most of this group do not develop kidney failure. For the few that do,
dialysis is required at about 70 years of age. Another small group of people
develop ADPKD without anyone in their family ever having suffered from
the condition.
Normal Kidney
12. Cysts in the kidney and polycystic kidney disease
Cysts
49
Y
Polycystic kidney disease
In this inherited disease, cystsdamage the kidneys resulting inblood in the urine and frequentkidney infections. Kidney failure andhigh blood pressure may also occur.
In patients over 50 years of age,
50% have one ormore simple cysts,
which usually do notcause symptoms or
long-term problems.
A GUIDE FOR PATIENTS
50
Polycystic kidney disease continued...
Can ADPKD be diagnosed before birth?
There is potential for antenatal screening for ADPKD as the location of
the gene is now known. Absense of a group of recently identified proteins
named polycystins, leads to the development of multiple cysts throughout
the kidneys.
How is ADPKD usually diagnosed?
Children born to people known to have ADPKD should be screened with
an ultrasound scan at about 18-20 years of age. If the ultrasound scan is
normal there is a less than 5% chance of that person developing the disease.
Later in life if the ultrasound scan is again normal at 30 years of age, there is
a less than 1% chance of that person subsequently developing the disease.
In the event of the offspring of a person with ADPKD not having an
ultrasound scan at the usual age, it is particularly important that it be
performed before starting a family in order for prenatal genetic counselling
to be undertaken. The potential carrier of the condition should inform
their partner of the risks of their offspring being affected.
What are the features of ADPKD?
The earliest sign of ADPKD is high blood pressure (hypertension), but blood
in the urine (haematuria), pain over the kidneys (pain in the back just below
the ribs) and/or a feeling of fullness in the abdomen may occur. In the
event of a cyst becoming infected, the patient may feel generally unwell and
experience pain and a high fever. Sometimes, in older people affected by
this condition, the first indication they are affected is when they develop
signs of uraemia (an excess of urea in the blood) (see also section 17).
There are effects of ADPKD, which occur outside the kidneys. These include
intracranial aneurysms (abnormalities of arteries in the brain which
predispose stroke), abnormalities of the heart valves and diverticulosis of
the bowel (abnormal out-pouchings of the large intestine). Evidence of
intracranial aneurysms should be sought if there is a family history of
ADPKD and stroke or ruptured aneurysm. They occur in about 5% of
people with ADPKD, but do not cause problems in the majority. People
with ADPKD may also develop cysts in their livers (especially women) and
less often in the pancreas, ovaries and lungs.
The earliest sign of ADPKD is high blood pressure(hypertension),but blood in theurine (haematuria),pain over the kidneys(pain in the back just below the ribs)and/or a feeling of fullness in theabdomen may occur.
51
The kidneys may grow to occupy most of the abdomen and occasionally
need to be removed if a dialysis patient with ADPKD is to receive a renal
transplant. Surgery is otherwise not helpful. There is no increased risk of
kidney cancer in ADPKD.
What treatment is available for people with ADPKD?
For people in whom the diagnosis is confirmed, high blood pressure should
be treated vigorously (see also section 11). This has been shown to slow
the rate of deterioration of the function of the kidneys. It is important to
rapidly treat other factors which have the potential to further damage the
kidneys such as urinary tract infections and kidney stones.
Many medications have the potential to cause harm to the kidneys and
these need to be avoided in people with ADPKD. Hence, it is important
to always confer with a doctor or kidney specialist before taking tablets
or alternative therapies. These measures, though they may not prevent
the ultimate failure of the kidneys, may at least delay the need for renal
replacement therapy (see also section 19).
For people in whomthe diagnosis is
confirmed, high bloodpressure should betreated vigorously.
This has been shownto slow the rate of
deterioration of thefunction of the kidneys.
It is important torapidly treat otherfactors which have
the potential tofurther damage the
kidneys such asurinary tract
infections and kidney stones.
A GUIDE FOR PATIENTS
52
Cysts continued...
Autosomal recessive PKD
This condition occurs in infants and young children. It is associated with
scarring in the liver (hepatic fibrosis) and has a poor prognosis. Many die
from renal failure in the first 12 months of life and the survivors may
develop liver failure from the age of 5-10 years.
Other cystic lesions in the kidney
These are defined by their localisation in the kidney, (eg. parapelvic cysts
impact on the pelvis of the kidney) or by their cause - for example,
hydatid cysts - (relatively rare), tuberculous cavities/cysts and carcinoma
where the central neoplasm (tumour) has become necrotic and hence may
appear cystic.
Medullary cystic disease
This (juvenile nephronophthisis) is a rare condition causing renal failure in
adolescents, who are often blonde or red-haired. It is associated with short
stature, bone disease (renal rickets), and salt wasting from the kidneys.
The blood pressure is usually normal even with advanced kidney failure.
It is sometimes associated with eye problems (Senior syndrome).
Medullary sponge kidney
This is relatively common and leads to small, often multiple stones in the
kidneys, which may be complicated by urinary infection. It rarely causes high
blood pressure or impairment of kidney function and is generally considered
to be a relatively harmless condition.
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