Your doctor will try to find out why your child has haematuria, though this is not always possible. Haematuria may happen:
- for a short period of time only, and may happen after lots of exercise or if there is irritation in the genital area – this is usually harmless
- during a urinary tract infection – the haematuria usually disappears after the child gets better
- because of an infection in another part of the body
- after surgery of the urinary tract
- because of a condition that affects the kidneys.
In many children, haematuria is mild.
How the kidney is involved
Haematuria normally happens when the kidneys leak red blood cells into the urine.
The kidneys have many tiny filters. They normally help remove extra water and waste, which are passed out in urine, and make sure the body keeps what it needs, including blood cells.
Is it always haematuria?
Sometimes haematuria can be mixed up with other things.
- Some foods, such as beetroot, can make the urine turn a reddish colour – this is not the same as blood in the urine.
- Some medicines can also make the urine turn a reddish colour. These medicines include rifampicin, nitrofurantoin and senna.
- Girls and women who have their menstrual period may sometimes see blood when they urinate
- Occasionally, there are other reasons that urine is a different colour than usual. Your child’s doctor or nurse will check for these.
Mild haematuria
Sometimes children leak a small amount of blood in the urine for a short period of time. This does not usually mean there is a problem, especially if:
- it happens after strenuous exercise
- there is irritation in the genital area
- the blood is not visible and it goes away when checked again.
A common cause of macroscopic haematuria (where there is visible blood) in children is a urinary tract infection (UTI), when germs get into the urine and travel up the urinary system.
The haematuria usually disappears after the child gets better, and does not cause any long-term problems..
Surgery
After some types of surgery, blood may get into the urinary system. Your surgeon or doctor will give you more information.
Haematuria caused by kidney conditions
Rarely, haematuria is caused by conditions that affect the kidney.
How the kidney works
Inside each kidney, there are about one million nephrons. Each nephron is made up of a glomerulus (when we talk about more than one glomerulus, we say glomeruli), and a renal tubule.
- Each glomerulus acts like a sieve, helping to remove extra water and waste from the body, and holding on to blood cells and protein, which the body needs.
- Blood flows into the kidneys and to each glomerulus.
- Most of the water and some other substances in the blood pass through the glomeruli.
- This liquid flows into the renal tubule. Most of this liquid moves back into the bloodstream. The rest of it becomes urine.
- The urine leaves the kidney by the ureters and goes into the bladder, where it is stored until we are ready to go to the toilet.
Kidney conditions that can cause haematuria
Occasionally, haematuria happens with post-infectious glomerulonephritis (PIGN). This condition happens in some children after they get an infection – usually in the throat, nose or sinuses, or the skin. About two weeks later, the immune system, which normally protects the body from infections and disease, causes inflammation (swelling) in the kidneys. This leads to PIGN.
Glomerulonephritis is a group of conditions that cause inflammation in the glomeruli. Children with this condition have blood and protein in their urine, and may have swelling in their body, especially around their face and legs. The conditions include:
- Alport syndrome, which is very rare and can run in families
- Cystic kidneys mean there are cysts, round swellings that may be filled with a watery liquid, in the kidney. These are a very rare cause of haematuria. The different diseases that cause cysts in the kidneys include: autosomal recessive polycystic kidney disease, autosomal dominant polycystic kidney disease and tuberous sclerosis.
- Vasculitis happens when the blood vessels in different parts of the body become inflamed. This can sometimes affect the blood vessels in the kidneys.
- Henoch–Schönlein purpura (HSP) – a type of vasculitis that affects different parts of the body – and IgA nephropathy are caused by problems with the immune system.
Kidney stones are small crystals, or clumps of hard material, that form in the kidney. They can cause pain when urinating. They are rare in children.
Blood clots (or thromboses) are clumps that form when the blood hardens.
- Renal vein thrombosis is a condition in which there are clots in the renal vein, the blood vessel that brings blood to the kidneys. This condition is most common in newborn babies who need an umbilical venous catheter. This is a flexible tube that is placed into the vein in the umbilical cord (where the tummy button is).
- Other blood diseases where the blood does not clot properly, such as sickle cell disease, may cause haematuria.
Thin basement membrane nephropathy is a rare condition that can run in families. One layer of the glomerulus leaks blood. This layer can look thinner than usual when looked at under a very high-power microscope. It does not usually cause long-term problems.