A GUIDE FOR PATIENTS

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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.