Polycystic kidney disease

What is PKD

In PKD, fluid-filled cysts develop in the kidneys, giving them a honeycomb appearance. Gradually these cysts replace the normal kidney tissue, enlarging the kidneys but making them less and less able to function normally. Eventually, the kidneys fail completely.

Symptoms

In addition to the kidney damage, the fluid in the cysts may become infected, which can cause pain in the back and abdomen, and trigger fever. They can also burst, causing pain, or blood in the urine.

Adults may not develop symptoms for many years. When they do arise they may also include:

• Vague discomfort or aching in the abdomen and/or lower back
• Attacks of sudden and severe pain in the abdomen and/or lower back
• Headaches
• Urinary tract infections
• Cysts in the liver and pancreas
• Abnormal heart valves
• Kidney stones
• Brain aneurysms (bulges in the walls of blood vessels)
• Diverticulosis (small bulges in the wall of the colon)

High blood pressure (hypertension) may develop as a result of kidney damage. This may exacerbate the problem by damaging the kidneys further. However, progress of the disease is usually very slow and it may go undetected for years.

What causes it?

There are two types of inherited PKD:

• Approximately 85-90 per cent of patients have ADPKD1 (with an abnormality on chromosome 16).
• The remaining patients have ADPKD2 (abnormality on chromosome 4).

It needs only one parent to pass on the abnormal gene, giving a person a one-in-two chance of developing the disease later in life.

The childhood form, autosomal recessive PKD, (ARPKD), is much rarer. It affects about one in 10,000 babies. In at least some cases, the gene is found on chromosome 6. It needs both parents to pass on an abnormal gene - meaning a child has a one in four chance of developing the disease in childhood which progresses rapidly.

The genes responsible for causing ADPKD in most patients have been identified. This means those with a family history of the disease can receive genetic counselling to help with family planning.

Diagnosis

Babies with ARPKD are usually identified soon after birth because the enlarged kidneys cause the abdomen to be very swollen, although this is very rare. Other organs such as the liver may be involved and, although severity varies, some babies die soon after birth.

If there's a family history of the disease, an ultrasound scan during pregnancy may detect the disease before the baby is born.

Adults with ADPKD may be discovered by chance when someone is undergoing tests for a separate problem. An ultrasound is the normal means of diagnosis. If there's a family history, it may be discovered when members of the family are routinely screened.

It's possible to screen for most ADPKD genes using DNA analysis during pregnancy.

Treatment and recovery

At present, it isn't possible to prevent the cysts forming within the kidneys. However, it's possible to slow the damage.

Keeping blood pressure at a safe level helps prevent further damage to the kidneys. If infection develops, it needs to be treated promptly and effectively.

Eventually, complete kidney failure often occurs. In 50 per cent of people with ADPKD, this happens by the age of 60. At this stage, kidney dialysis or transplant can be necessary.

Advice and support

PKD Charity

• Tel: 0300 111 1234
• Email: support@pkdcharity.org.uk
• Website: www.pkdcharity.co.uk