What is sickle cell nephropathy?

Sickle cell disease is the most common inherited blood disorder in the UK. It affects the red blood cells and causes them to be misshaped and take the form of rigid sickles or crescents instead of the normal flexible discs. This occurs after a certain trigger such as a cold, stress, infection or low oxygen levels. The misshapen red blood cells do not live as long as normal red blood cells and can block blood vessels, which can lead to organ damage and cause painful episodes known as crises.

Sickle cell nephropathy is a complication of sickle cell disease. People with sickle cell disease have an increased risk of developing chronic kidney disease (CKD) and acute kidney injury (AKI).

Sickle cell disease affects around 15,000 people in the UK, with around 300 babies born each year with the condition. It is more common in people from African and Caribbean backgrounds but it also affects people from Mediterranean, Middle Eastern, and South Asian backgrounds.

Sickle cell nephropathy affects around 1 in 2 people with sickle cell disease.

What are the signs and symptoms of sickle cell nephropathy?

Kidney problems often develop slowly and may not cause obvious pain. This is different from the painful crises that many people with sickle cell disease experience.

Symptoms of sickle cell nephropathy include:

• protein in the urine (proteinuria) – this is likely to only be seen under a microscope or when tested by dipping a specially treated paper strip into your urine (urine dipstick). However, if there is a lot of protein, the urine may look frothy.
• blood in the urine (haematuria) – this is often visible, making the urine a reddish-pink colour (microscopic haematuria). This is different to the slightly darker, amber coloured urine that occurs in jaundice, which can also develop due to sickle cell disease.
• high blood pressure
• urinary tract infections
• abdominal pain

1 in 10 people with sickle cell nephropathy develop kidney failure.

These symptoms can occur alongside those for sickle cell disease, which include:

• sickle cell crises – very severe bouts of pain that can last for several days or weeks
• increased risk of infection
• anaemia – a shortage of red blood cells
• delayed growth
• increased chance of strokes

What causes sickle cell nephropathy?

Sickle cell nephropathy is a complication (side effect) of sickle cell disease, which occurs due to a fault in the gene that affects how red blood cells develop. The kidneys are affected by sickle cell disease because sickle-shaped red blood cells can block the small blood vessels of the kidneys, reducing their oxygen supply and causing gradual scarring.

Several risk factors increase the chance of developing kidney damage:

• Anaemia: Severe or persistent anaemia puts extra stress on the kidneys
• Medications: Certain medications, including non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can harm the kidneys if used regularly
• High blood pressure: Even slightly raised blood pressure can speed up kidney damage
• Diabetes: People with both diabetes and sickle cell disease have a much higher risk of developing kidney damage.

How is sickle cell nephropathy diagnosed?

Sickle cell nephropathy is diagnosed by blood and urine tests to check the function of the kidneys as one of the earliest signs of kidney damage is having protein in the urine (proteinuria).

Standard kidney blood tests can sometimes underestimate the severity of kidney disease in people with sickle cell disease. This is because:

• The kidneys in sickle cell disease often have a much higher blood flow (cardiac output), which can mask early signs of damage.
• Many people with sickle cell disease have lower muscle mass compared with the general population. Because creatinine (the substance used to estimate kidney function in blood tests) comes from muscles, this can make kidney function look better than it really is.

Doctors therefore also use urine tests and specialist kidney assessments rather than blood tests alone.

• Proteinuria is an important warning sign of kidney disease and a strong indication of how the disease may progress.
• 8 out of 10 people with sickle cell nephropathy have proteinuria by the age of 40
• Keeping protein levels low is one of the most important goals in protecting kidney health.

Ultrasound, CT or MRI scans may also be recommended.

Does sickle cell nephropathy affect other parts of the body?

Sickle cell nephropathy only affects the kidneys but sickle cell disease can affect other parts of the body, including the lungs, heart, liver and spleen.

Does sickle cell nephropathy run in families?

Sickle cell nephropathy can run in families as it is a complication of sickle cell disease which is an inherited condition.

Everybody has two copies of the sickle cell gene, one from each parent.

Healthy people have two normal copies.

Carriers have one copy that works normally and one that doesn’t. Carriers are usually healthy because the normal copy can still do its job. However, they can still pass sickle cell disease on to their children.

In people with sickle cell disease, neither copy of the gene works properly. They inherit faulty copies of the gene from each parent – either because their parents have sickle cell disease themselves or they are carriers.

If both parents have sickle cell disease, all of their will have also have sickle cell disease.

Some people have both sickle cell disease and another genetic abnormality of red blood cells called haemoglobin C, beta-thalassaemia.

How is sickle cell nephropathy treated?

Treatment for sickle cell nephropathy is part of wider sickle cell disease treatment and includes:

• Drinking plenty of fluid and staying warm to help prevent or lessen painful sickle cell crises
• Medication including painkillers for sickle cell crises and antibiotics to prevent infections. A medication called hydroxycarbamide (also known as hydroxyurea) increases production of fetal haemoglobin (HbF) which helps to reduce sickling in red blood cells. People with sickle cell disease who start hydroxycarbamide early in life have 50% fewer complications than those who did not take the medication.
• Regular blood transfusions for severe symptoms

Kidney-specific treatment may include:

• Controlling your blood pressure. High blood pressure can speed up kidney damage. You may be prescribed blood pressure medication to keep your blood pressure under control. This is often in the form of medication such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs).
• Sodium-glucose cotransporter 2 (SGLT2) inhibitors slow down the progression of kidney disease.
• Dialysis or transplant may be needed if your CKD progresses to kidney failure.

Currently the only cure for sickle cell disease is a bone marrow or stem cell transplant but these are rare as they need a closely matched donor.

New advances in gene therapy are showing positive results. The treatment edits a gene in the patient’s bone marrow stem cells so that their body produces functioning haemoglobin. It is currently unknown how this treatment will affect the kidneys.

Where can I get more information or support about sickle cell nephropathy?

For more information on sickle cell disease, including its genetics, diagnosis, symptoms and treatment, visit Sickle Cell Society.

Publication date: 11/2025

Review date: 11/2028