The symptoms of glomerulonephritis are not always obvious, so it is sometimes only diagnosed after a routine medical check-up or during tests related to:
- having high blood pressure (hypertension)
- feeling tired
- feeling unwell for a long time without an obvious cause
- being pregnant
The presence of kidney disease will be picked up in two ways:
- during a blood test to measure the kidney’s function
- during a urine test to look for abnormal levels of protein or blood
Blood test
A blood test can be used to measure your creatinine level. Creatinine is a substance produced by your muscles that is present in your blood stream. The kidneys remove creatinine from the blood as part of their usual role.
If your kidneys are not working normally, the creatinine level in your blood will rise, and this can be detected during a blood test.
The creatinine result is converted into what is known as the estimated glomerular filtration rate (eGFR). The eGFR is the best guide to kidney function.
Urine test
Your urine can be tested in two ways:
- Your GP or another healthcare professional can dip special strips into a sample of your urine. This is called the dipstick technique, and the strip changes colour if there is any blood or protein in your urine.
- A sample of your urine is sent to a laboratory to more accurately measure how much protein it contains or to look for blood cells.
The dipstick technique is generally considered to be better at determining whether there is blood in your urine. The laboratory test is better for measuring protein levels.
If you have glomerulonephritis, these tests may show evidence of too much protein or blood in your urine, or both. You may also have an abnormal eGFR. Putting this information together will allow your GP to decide whether you need to see a specialist for further investigations.
Specialist blood tests
Several specialist blood tests may be carried out to look for causes of glomerulonephritis. These include:
- tests to look for systemic lupus erythematosus, such as an anti-nuclear antibody test - see Systemic lupus erythematosus - diagnosis for more information
- the anti-neutrophil cytoplasmic antibody blood test - used to diagnose vasculitis (a condition that affects the small blood vessels of various organs in the body)
- the anti-glomerular basement membrane blood test - used to diagnose Goodpasture’s disease (when antibodies attack the membranes of the glomeruli)
Kidney ultrasound
If your kidney problem needs to be investigated further, it is likely that you will need to have a kidney ultrasound scan.
An ultrasound scan uses high-frequency sound waves to allow the specialist to look at images of your kidneys. The specialist will be able to check the size of your kidneys, make sure there are no blockages and look for anything else that might explain why they are not working as they should.
If you need a kidney biopsy (see below), you will need a kidney ultrasound scan first.
Kidney biopsy
If glomerulonephritis is suspected, a procedure to remove a small sample of kidney tissue (a biopsy) may be recommended. See the Health A-Z topic about Biopsies for more information.
A kidney biopsy is usually carried out using local anaesthetic to numb the area. An ultrasound machine will be used to locate your kidneys and a small needle will be used to take a sample. The test carries a small risk of bleeding so you will need to remain in hospital for a while on the day of the procedure, or sometimes overnight.
After the procedure, the tissue sample will be examined under a microscope in a laboratory to find out how serious the condition is and to determine the most appropriate type of treatment.
