The symptoms of autosomal recessive polycystic kidney disease (ARPKD) can vary significantly, even within the same family.

Generally, however, the main symptoms of ARPKD differ, depending on when the condition first becomes apparent.

In many cases, potential signs of ARPKD can be detected before birth during routine ultrasound scans.

If your baby has the condition, an ultrasound scan may show that:

• they have enlarged kidneys
• their lungs are underdeveloped
• there's a lack of amniotic fluid surrounding your baby

When your baby is born, there may be clearer signs that suggest they have ARPKD, such as:

• significant breathing difficulties – this is caused by the lungs being underdeveloped
• a swollen tummy (abdomen) – caused by enlargement of the kidneys
• Potter's syndrome – where a lack of amniotic fluid leads to deformities of the limbs, face and ears; Potter's syndrome is a possibility in severe cases of ARPKD

Underdeveloped lungs is the biggest problem immediately after birth, and breathing assistance with a ventilator is often needed. A ventilator is a machine that moves air in and out of the lungs.

Around 1 in every 3 babies with ARPKD who develop breathing difficulties soon after birth will die within a few weeks or months.

9 in 10 babies who survive the first 4 weeks are still alive at 5 years old, and most children now live into adulthood.

About 6 in 10 children with ARPKD will need dialysis or a kidney transplant by the age of 10.

ARPKD tends to be less immediately life threatening in infants and older children, although the condition can still cause a wide range of serious problems.

Some of the main problems infants and children with ARPKD experience are described below.

High blood pressure

High blood pressure (hypertension) is a common problem for children with ARPKD.

If your child has high blood pressure, they'll usually need to take medication to lower it and prevent long-term damage to their heart and blood vessels. 

Liver problems and internal bleeding

For children with ARPKD, a number of problems affecting the liver can also develop.

For example, the small tubes called bile ducts that allow a digestive fluid called bile to flow out of the liver may develop abnormally and cysts may grow inside them.

Over time, the liver can also develop fibrosis, a process similar to scarring. This restricts the blood flow through the liver and increases the pressure in its delicate blood vessels (portal hypertension).

When this occurs, blood bypasses the liver and is diverted into veins. These veins then become swollen, particularly in the lower gullet (oesophagus). They can bleed if they get too big.

Portal hypertension also diverts blood to the spleen, causing it to become enlarged. This can affect the spleen's normal functions, such as removing old or damaged blood cells from the blood.

An enlarged spleen may remove too many of these cells, including platelets, which can increase the risk of internal bleeding, particularly from any varices that have developed.

Platelets are tiny cells that cause the blood to thicken (clot) if a blood vessel is damaged.

Internal bleeding can be rapid and severe, causing your child to vomit blood or pass stools that are very dark or tar-like.

Excessive peeing and thirst

In ARPKD, the small tubes (tubules) that make up the kidneys can develop abnormally, causing bulges and fluid-filled sacs called cysts to form within them.

The tubules are important in regulating how much water is held in the body. This is disrupted in ARPKD, which is why small children lose excessive amounts of body fluid as urine.

This can lead to:

• polyuria – where your child will need to pee frequently and may wet the bed
• polydipsia – an excessive and prolonged thirst

These symptoms increase the risk of dehydration, particularly if the child also has a high temperature, is vomiting, or has diarrhoea.

Signs and symptoms of dehydration can include:

• a dry mouth and lips
• sunken features (particularly the eyes)
• headaches
• dizziness
• irritability

Contact your child's kidney specialist if you think your child may be becoming dehydrated, as regular dehydration treatments, including oral rehydration treatments like Dioralyte, may not be suitable for them.

Get medical advice straight away if you're concerned about your child's symptoms.

Feeding problems

Your child may have problems feeding because their enlarged kidneys take up most of the space in their abdomen.

They may vomit after eating, and may only be able to eat small amounts at a time.

If this leads to malnutrition, your child may need to be fed through a tube inserted into their stomach, either through the nose or abdomen.

Faltering growth

Some children with ARPKD do not grow at a normal rate. Doctors call this faltering growth or failure to thrive, and it's usually caused by a combination of factors.

Children with ARPKD may be under the care of a dietitian, who may recommend a high-calorie and high-protein diet to boost their weight.

Some children may also need to be fed through a tube if they're having feeding problems.

Chronic kidney disease and kidney failure

Most people with ARPKD lose a significant amount of kidney function. Loss of kidney function caused by kidney damage is called chronic kidney disease (CKD).

CKD does not usually cause any symptoms until it's reached an advanced stage.

The most advanced stage of CKD is known as kidney failure or end-stage renal disease. This occurs when the kidneys have lost almost all of their ability to function.

Symptoms of kidney failure can include:

• poor appetite and weight loss
• swollen ankles, feet or hands (oedema)
• shortness of breath
• an increased need to urinate, particularly at night (nocturia)
• itchy skin
• feeling sick

Most children with ARPKD will develop kidney failure by the time they're 15 to 20 years old.

They'll need either a kidney transplant or dialysis, where a machine is used to replicate many of the functions of the kidneys.