Kidney Problems and Sickle Cell Disease
The kidneys are especially sensitive to sickled red blood cells. People with sickle cell disease (SCD) can develop chronic kidney disease because of reduced blood flow to the kidney.
Chronic kidney disease can lead to end-stage renal disease (ESRD) and is a common cause of death for people with SCD. If you have symptoms of kidney damage, call your doctor. They can perform tests to determine the cause. They can also determine the best treatment to prevent chronic kidney disease from worsening to end-stage renal disease.
What kidney problems do people with sickle cell disease experience?
Chronic kidney disease is common in SCD and shows a range of conditions, called sickle cell nephropathy (SCN). The kidney filters waste from our blood and produces urine. It also makes urine concentrated to reduce the amount of water needed to remove waste.1
When the kidney does not get enough oxygen, kidney cells begin to die. The kidney gradually loses its ability to filter out waste. This may cause proteins that are normally saved by the kidney to be lost in urine (proteinuria).1,2
Without oxygen, the kidney also cannot absorb water from urine, leading to urine with too much water in it (hyposthenuria). This can lead to excessive and nighttime urination. Kidney problems can also cause bloody urine (hematuria). However, hematuria may be caused by other SCD-related complications, such as urinary tract infections and a kidney cancer called renal medullary carcinoma.3-5
Children and adults with SCD should be regularly tested for kidney disease. Doctors will perform lab tests on blood and urine to determine if you have kidney problems, such as proteinuria, hyposthenuria, or hematuria. They may also analyze how much creatinine is in your blood and urine. Creatinine is a waste product released into urine by the kidneys. Creatinine concentrations in blood and urine can tell doctors how well the kidney is filtering blood.1,6
Acute kidney injury (AKI) is also common in children and adults with SCD. This is a sudden rise in blood creatinine levels. Most people recover kidney function after an episode, but repeated episodes may lead to chronic kidney disease.7
Why does SCD cause these problems?
Sickle cell neuropathy leads to chronic kidney disease in 1 out of every 3 to 4 adults with SCD. People with sickle cell anemia (HbSS) or sickle beta zero thalassemia have a higher risk than people with other types of SCD. About 1 in 6 people with SCD die because of chronic kidney disease. On average, people with SCD who have kidney failure live about 12 years shorter than people with SCD who do not.8-10
SCD causes kidney problems when sickle cells block blood flow in the kidney. The blood vessels leading to the innermost part of the kidney are most susceptible to sickling. This is because it is a relatively acidic area with low oxygen. In this environment, sickle hemoglobin proteins are more likely to form rigid strands inside red blood cells and produce sickle-shaped cells.11,12
Sickle cells in the kidney block flow and change the way blood vessels work. This reduces oxygen delivery and causes kidney cells to die. This leads to the kidney issues seen in SCN.
What are the symptoms?
Some symptoms of chronic kidney disease include:1,6,13
- Frequent urination
- Nighttime bedwetting
- High blood pressure (hypertension)
- Bloody urine
- Nausea and vomiting
- Fatigue and weakness
- Shortness of breath and chest pain
People with SCD often have a low blood pressure. This mean that a relatively “normal” blood pressure may sometimes actually be a sign of hypertension (high blood pressure) and kidney disease.14
These are not all the symptoms of kidney disease, and many of these symptoms can be caused by other complications of SCD. If you experience any symptoms of kidney disease, talk to your doctor about getting tested for kidney function.
How can these problems be prevented and treated?
Certain medications can be toxic to the kidney. Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen are usually safe for short-term doses, but regular usage can increase the risk of kidney damage. Acetaminophen is a better alternative to treat fever and routine minor pain.6
Hydroxyurea may improve kidney function in children and adults with SCD. Doctors may recommend taking hydroxyurea with ACE inhibitors (drugs often used to treat high blood pressure and heart failure) to prevent or treat kidney damage. Blood transfusions are usually not used to treat kidney problems; however, poor kidney function can worsen anemia.15-17
About 1 in 10 people with SCD who have chronic kidney disease develop end-stage renal disease. This is a complete failure of the kidneys to work. Treatment will usually involve dialysis or a kidney transplant. Dialysis is a medical service where a person is connected to a machine that filters their blood, like their kidneys would. This is typically done for 3 to 4 hours a day for 3 days a week. A kidney transplant is a surgery where a healthy kidney is taken from a donor and placed into the body of a person with end-stage renal disease.
People with SCD are less likely to be placed on a kidney transplant list than people without SCD. This may be because of racial biases or concerns about complications. It is 1 reason why people with SCD have a lower survival rate from kidney failure than people without SCD.18,19