Glomerulonephritis: symptoms, causes, tests and treatment

The glomeruli are the tiny filters inside the kidneys. In glomerulonephritis they become damaged. The NHS says this is often caused by the immune system attacking healthy body tissue.

Kidney Research UK explains that the usual job of the immune system is to fight germs, but sometimes it makes a mistake and attacks the filters as if they were invaders. It also notes that it is not clear why this happens in many cases, and that an infection can sometimes act as a trigger.

The term covers many different diseases. Kidney Research UK lists several types, including IgA glomerulonephritis, membranous glomerulonephritis, membranoproliferative glomerulonephritis, minimal change nephropathy, focal and segmental glomerulosclerosis, and vasculitis. They differ in what causes them and how they behave, which is why a precise diagnosis matters.

The NHS says mild cases can be treated effectively, but for some people the condition can lead to long-term kidney problems.

Many people have no symptoms at all. Kidney Research UK says the only sign may be small amounts of blood or protein in the urine that can be detected only on a urine test. The NHS makes the same point: mild glomerulonephritis does not usually cause noticeable symptoms and is more likely to be found when tests are done for another reason.

When damage is more severe, the NHS describes the following:

• Dark-coloured pee because it contains blood. The blood may also be seen only when a sample is tested.

• Frothy pee if it contains a large amount of protein.

• Swelling of the legs or other parts of the body when a lot of protein leaks into the urine. The NHS calls this nephrotic syndrome.

• High blood pressure in some people.

Depending on the cause, the NHS says other parts of the body can be affected. It lists rashes, joint pain, stomach pain, a high temperature, shortness of breath, yellowing of the whites of the eyes or skin (jaundice, which may be less noticeable on brown or black skin), peeing a lot less than usual, tiredness, and loss of appetite and weight loss.

Kidney Research UK adds that most people with glomerulonephritis do not get pain around the kidneys, although in a few cases it can be severe, particularly during bouts of visible blood in the urine. It also says that visible blood sometimes appears only when the person is ill for another reason, such as a respiratory infection.

The NHS says glomerulonephritis often happens if there is a problem with your immune system. It can be caused by inflammatory conditions such as systemic lupus erythematosus (SLE) or vasculitis.

In some cases it can be caused by infections. The NHS lists HIV, hepatitis B and hepatitis C, and infection of the inner lining of the heart (endocarditis). It adds that some types of cancer and certain medicines can also cause it, and that sometimes it is not clear what causes it.

Some forms are inherited. The NHS says that if you are diagnosed with an inherited type, a doctor can advise about the chance of someone else in your family being affected and may recommend screening. Kidney Research UK says diagnosis of these types usually requires analysis of your DNA.

Kidney Research UK also describes one type in which an unusually sticky form of immunoglobulin A (IgA) becomes trapped in the glomeruli, causing damage and scarring. That is the pattern seen in IgA nephropathy.

The NHS says that if a GP suspects glomerulonephritis they will usually arrange blood tests, to check how much protein is in the blood and to measure creatinine (a waste product made by your muscles), and a urine test to check for blood or protein.

If the diagnosis is confirmed, further blood tests may be needed to find the cause. Kidney Research UK says blood tests may look for abnormal antibodies.

If the kidney problem needs further investigation, the NHS lists two more tests. An ultrasound scan checks the size of the kidneys and looks for blockages or other problems. A kidney biopsy removes a small sample of kidney tissue using a needle, after local anaesthetic, with an ultrasound machine used to locate the kidney. Kidney Research UK says a biopsy may be needed for an accurate diagnosis and may also help show whether the condition is likely to become serious and which treatments could help.

The NHS says treatment depends on what is causing the condition and on your symptoms. If you have severe glomerulonephritis you will usually be referred to a kidney specialist (nephrologist). Kidney Research UK says some types can be cured, others can be stopped, and most can at least be slowed down.

The NHS treatment page describes these elements:

• Treating an underlying condition, where one can be identified.

• Blood pressure medicines, such as ACE inhibitors or angiotensin receptor blockers (ARBs). These are commonly prescribed because they help protect the kidneys and reduce the amount of protein that leaks into the urine. People with high blood pressure and kidney disease often need several medicines.

• Immunosuppressants, if the cause is a problem with the immune system. These suppress the immune system, which can be effective but increases the risk of infections and can cause other side effects such as thinning of the bones.

• Steroids such as prednisolone, to reduce swelling and suppress the immune system. The dose is usually lowered once the kidneys have started to recover.

• Medicines to prevent side effects, such as infections and osteoporosis, if you take immunosuppressants or steroids.

• Antiviral medicine if the condition is thought to be linked to a viral infection.

• Treating individual symptoms, for example a diuretic for fluid build-up.

In mild cases, the NHS says a GP or dietitian will give relevant diet advice. You may be advised to reduce the amount of salt, fat, protein and potassium in your diet and to drink less fluid. This should help control blood pressure and regulate the amount of fluid in your body. Eating less salt reduces the strain on the kidneys.

You should have regular reviews to check blood pressure, the levels of salt and potassium in your pee and how well your kidneys are working.

The NHS also says smoking may make kidney disease caused by glomerulonephritis worse and increases the risk of complications such as heart disease and stroke, which are more common in people with the condition.

Dietary advice is individual, because it depends on your blood results and treatment. Follow the plan given by your kidney team or dietitian rather than restricting foods on your own.

The NHS says that although treatment is effective in many cases, further problems can sometimes develop. These include high blood pressure, high cholesterol, blood clots (including deep vein thrombosis and pulmonary embolism), damage to other organs, chronic kidney disease and kidney failure.

If you are diagnosed, the NHS says a doctor may prescribe medicine to lower your blood pressure, lower your cholesterol or protect against blood clots.

Kidney Research UK says that in some cases the damage can be severe enough to cause kidney failure, also described as end stage kidney disease, and that some types can come back after a kidney transplant.

The NHS says to see a GP if you notice blood in your urine. This does not always mean you have glomerulonephritis, but the cause should be investigated. See a GP too if you have other symptoms such as joint pain, tiredness and shortness of breath.

Because mild disease can be silent, blood pressure checks and urine tests can matter if you have a condition that affects the kidneys, such as lupus. Ask your GP or specialist how often you should be checked.

If you feel seriously unwell, are passing very little urine, or are struggling to breathe, seek urgent help through NHS 111, and call 999 in an emergency.

On the NHS, testing usually starts in primary care with blood and urine tests. If glomerulonephritis is suspected or confirmed, the GP refers you to a kidney specialist, who arranges scans, a biopsy and treatment. Long-term monitoring and any dialysis or transplant planning are provided by renal services.

Some people choose to see a kidney specialist privately for a faster appointment or a second opinion. The tests and treatments are the same in principle, and results should be shared with your GP so your records stay complete.