The red blood cell is an important cell component of the blood and functions to deliver oxygen to all the tissues. Each red blood cell contains what is called hemoglobin, the vehicle for carrying oxygen within the red blood cell. Abnormalities of the hemoglobin in the red blood cell can make the red blood cell function abnormally and cause serious problems in tissues of the body including the bone, brain, intestines, lung and even the kidney.
Sickle cell disease is also called sickle cell anemia or drepanocytosis. It is a hereditary disorder of red blood cells most common in Africa and in persons of African descent where under stressful conditions such as infection, dehydration or low oxygen tissue supply, the red blood cells assume an abnormal rigid sickle shape - a process called sickling. Sickling decreases the flexibility of the red blood cell makes the red blood cell unable to pass through the blood vessels easily and for this reason reduces oxygen supply to tissues including the kidneys. If this sickling happens sufficiently, it can cause damage in these tissues and even death.
There is also a less severe form of the sickling condition called the sickle cell trait or "AS" condition, where in simple language only half of the hemoglobin expressed is at sickling risk. Because the other half of their available hemoglobin is normal, they can provide oxygen better to tissues and are at much lower risk for clinical problems although if stressors are very severe, they may develop crises.
The number of people living with sickle cell disease is highest in Nigeria where over a million people live with the full sickle cell disease (SS) and over 30 million live with the sickle cell trait (AS). There are also high numbers of people born with the disease in east Africa (specifically, the Democratic Republic of Congo) and India. It has been estimated that about 90,000 babies were born with sickle cell disease in 2010 and this number is expected to grow to about 150,000 in 20501. This therefore means that a larger number of people will be alive with the disease and attention has to be paid by doctors in caring for the people as the number of cases of kidney disease due to sickle cell anemia will also increase.
Sickle Cell Disease and the Kidney
About 1 or 2 out of every 20 patients with sickle cell disease will develop problems with decreased kidney function. The number of patients with sickle cell disease and kidney problems increases with age and among sicklers alive and over the age of 45, 6 out of 10 of them will have kidney problems requiring medical attention. However, only 1-5 out of 20 sickle cell patients with kidney disease will go on to develop kidney failure requiring dialysis or kidney transplantation.
Problems with the kidney due to sickle cell disease is usually due to sickling in the small blood vessels of the kidney. The beginning of kidney problems in patients with sickle cell disease is usually quiet starting between the ages of 10 and 20 without symptoms. This symptom free stage is however progressive and requires close attention by doctors to detect early.
The most common signs of kidney disease in sickle cell patients is -
- Frequent urination and increased volume of urine. Noticed even in the first 10 years of life and is just another reason for sicklers to always remain well hydrated and drink sufficient amounts of water
- The presence of protein in the urine,
- The presence of blood even in microscopic amounts in the urine
- The development of high blood pressure and
- Worsening anemia.
The presence of any of these problems in a sickler should push the patient and doctor to pay close attention to kidney function in order to prevent progression to kidney failure. Majority of patients with sickle cell disease and kidney failure present between the ages of 20 and 40 years and these patients often are dead within 4 years of diagnosis of kidney failure.
It may appear that the number of people with sickle cell disease and kidney disease is low. However kidney failure is clearly an identified risk for death among sicklers so it is important to prevent kidney disease due to sickle cell anemia and control of kidney disease in those who already have poor kidney function is important.
It is equally important to note that not all kidney disease in patients with sickle cell anemia is due to sickle cell disease. Other causes of kidney disease in these patients might include lupus, or infection with hepatitis B, Hepatitis C or HIV. These infections are common infections among Nigerian sickle cell patients because of all the blood transfusions they often need over time that puts them at increased risk for acquiring the infections.
For more information on the concerns about blood transfusion and how they may be of importance to sickle cell patients, read our recent blog post about these infections by clicking here.
Sickle cell disease patients also appear to be at increased risk for medullary cancer of the kidney. This often presents with abdominal pain, a swelling in the abdomen, blood in the urine and weight loss. Any sickle cell patient with these symptoms must discuss immediately with their doctor.
What to Do to Prevent or Control Kidney Disease and Symptoms in Sickle Cell Patients
(Please note that these recommendations are only good practices to help empower patients with sickle cell disease. They do not replace the need to see a trained medical professional for detailed proposals for treatment and follow up.)
- Be vigilant for signs and symptoms of kidney disease such as increasing blood pressure and blood in the urine.
- Visit your doctor regularly and ask for a kidney check up with blood and urine tests.
- Drink plenty of water
- Pay attention to controlling blood pressure.
- Make sure as a sickler you get vaccinated against common infections. Fevers and infections are dealt with as quickly as possible by seeing a doctor.
- If you already have some kidney disease as a sickler make sure you are seen from time to time by a kidney specialist
- Talk to your doctor about medications like EPO, iron and vitamins you can take to increase blood production and decrease the need or frequency of blood transfusions.
Piel FB, Hay SI, Gupta S, Weatherall DJ, Williams TN. Global burden of sickle cell anaemia in children under five, 2010-2050: modelling based on demographics, excess mortality, and interventions. PLoS Med. 2013;10(7):e1001484. doi: 10.1371/journal.pmed.1001484. Epub 2013 Jul 16.
Saborio P1, Scheinman JI. Sickle cell nephropathy. J Am Soc Nephrol. 1999 Jan;10(1):187-92.
Sharpe CC, Thein SL. Sickle cell nephropathy – a practical approach. Br J Haematol. 2011 Nov;155(3):287-97. doi: 10.1111/j.1365-2141.2011.08853.x. Epub 2011 Sep 9. Review.
Wong WY, Elliott-Mills D, Powars D. Renal failure in sickle cell anemia. Hematol Oncol Clin North Am. 1996 Dec;10(6):1321-31.
Important Web Links for Patients
The sickle cell foundation of Nigeria: http://www.sicklecellfoundation.com/
World Health Organization Fact sheet on sickle cell disease: http://www.who.int/mediacentre/factsheets/fs308/en/
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