Your child will need some tests to diagnose (identify) MPGN, find out more about how it is affecting him or her and whether any treatment is needed. Your child may need an examination, urine tests, blood tests, imaging tests and a kidney biopsy.
Examination
Your doctor will talk to you or your child about his or her symptoms and any medicines that he or she takes. The doctor will examine your child – for example, to see whether he or she has oedema (swelling in their body). Your doctor or nurse will check your child’s blood pressure. This is because MPGN may cause high blood pressure (hypertension).
Urine tests
You, or a nurse, will need to collect some of your child’s urine in a small, clean container for a urine test. A dipstick will be dipped into the urine – this is a strip with chemical pads that change colour depending on what substances are in the urine. This shows whether there are blood cells and/or protein, which are signs of MPGN. The sample may also be sent to a laboratory for more accurate tests.
Blood tests
A small amount of blood will be taken from a vein, with a needle and syringe, for a blood test. A special gel or cream can be used to help your child stop feeling any pain. The blood test results can give the doctor more information, including:
- about the immune system, and whether there has been a recent infection
- how well his or her kidneys are working – this is called the kidney function
- the amount of protein in your child’s blood – in MPGN, the kidneys leak protein into urine and this is sometimes enough to affect how much is in the blood.
Read more about blood tests for MPGN
How well the kidneys are working
A blood test can find out the estimated glomerular filtration rate (eGFR), the amount of fluid that the kidneys filter each minute. A low eGFR means that the kidneys cannot filter as quickly, and so are not working as well as normal.
Infection and immune system
A blood test can check whether there are any antibodies – the body’s immune system makes these special proteins to identify and kill specific germs. This gives information about whether there has been an infection, and sometimes which germ caused it. Antibodies can also cause problems if they get trapped in the glomeruli.
Children with MPGN may have low levels of a protein called complement C3, which is also part of the immune system. This complement works with antibodies to help kill cells infected by germs.
Protein in the blood
Some children with MPGN lose a lot of protein in their urine, when it is leaked through the glomeruli. This means there is less protein in their blood, especially a type of protein called albumin. Because albumin is smaller than other proteins, it is more likely to leak through the glomeruli, the kidney filters.
Imaging tests
Some children need imaging tests (scans). These use special equipment to get images (pictures) of the inside of their body.
- Ultrasound scan – looks at the shape and size of kidneys and other parts of the urinary system. A small handheld device is moved around your child’s skin and uses sound waves to create an image on a screen.
- Chest X-ray – for children with breathing problems, this test checks for any fluid (liquid) around the lungs. Your child sits or lies still for a few seconds while a machine takes X-ray images.
Occasionally, other imaging tests are needed.
Kidney biopsy
Your doctor can diagnose MPGN with a kidney biopsy, and may recommend this test. A tiny piece of one kidney is removed from the body with a needle, and examined under microscopes. Special medicines are used so your child does not feel any pain or can sleep through the procedure.
A kidney biopsy can give more information about how much damage there is in your child’s kidney, and confirm whether he or she has MPGN or another type of glomerulonephritis. The kidney biopsy also shows the type of MPGN – type 1, type 2 (dense deposit disease) or type 3. It can take a few weeks to get the results.