What happens

In CKD, there may be an imbalance of chemicals (electrolytes) in the blood, because the kidneys are less able to control the amounts of these. This may lead to serious and potentially life-threatening complications.

Common imbalances in CKD are:

  • hyperphosphataemia – high levels of phosphate
  • hyperkalaemia – high levels of potassium
  • hypocalcaemia – low levels of calcium
  • hypercalcaemiahigh levels of calcium.

To reduce these serious risks – both in childhood and later in life – your child needs to carefully follow the treatment plan set by your doctor. This will probably include restricting which foods he or she can eat, and taking medicines. It is crucial to do this – especially as there are often no symptoms or warning signs.

Renal bone disease

Hyperphosphataemia and hypocalcaemia may cause the bones to become less strong and so they may not grow normally. This is called renal bone disease (renal osteodystrophy).

How this happens

  • The kidneys are less able to remove phosphate into urine. This means there is a high level of phosphate and a low level of calcium. This triggers the body to release parathyroid hormone (PTH). PTH is a type of hormone, which is a chemical that is carried in the blood to send messages to other parts of the body.
  • PTH increases calcium in the blood by removing it from the bones, causing renal bone disease.

Diseases of the heart and circulation

There is a risk of developing cardiovascular disease (CVD), which is disease of the heart and blood vessels. In children with CKD, this may be associated with:

  • high blood pressure (hypertension) – which can affect the heart
  • an imbalance of calcium and phosphate – which causes the blood vessels to get stiff, and makes it more difficult for the blood to circulate.

Cardiac arrest

In serious cases, hyperkalaemia can cause a cardiac arrest, a life-threatening emergency in which the heart suddenly stops pumping blood.


Parathyroid hormone (PTH)

PTH is a hormone that is released into the blood stream by the parathyroid glands, which are in the neck. Both PTH and vitamin D work with chemicals such as calcium and phosphate for bone development and growth. In later stages of CKD, some children have too much PTH. If this happens, your child may need medicines to keep PTH at the right level.

Phosphate binders

Kidneys with CKD are less able to remove phosphate from the body, which can increase the risk of bone problems. Phosphate binders – (e.g. calcium carbonate, Tums, sevalemer (Renagel) – bind phosphate from food in your child’s gut, so that less gets into his or her blood.

More about calcium salts on Medicines for Children