Yes. Some forms of kidney disease can raise the chance of a blood clot, especially nephrotic syndrome, in which damaged kidney filters let too much protein pass into urine. This can make blood more likely to clot. However, kidney disease does not always cause clots, and the risk depends on the type and activity of the condition and other health factors. Sudden breathing trouble or chest pain needs emergency care.
How can kidney disease increase the risk of blood clots?
The kidneys do more than remove waste from the blood. They also help keep important proteins in the bloodstream. When certain kidney conditions damage the tiny filtering units, large amounts of protein can leak into the urine. This can lead to changes in the blood that increase its tendency to form clots.
One condition strongly associated with this complication is nephrotic syndrome. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), nephrotic syndrome can cause blood clots, as well as swelling and low levels of albumin, a protein in the blood. The condition can result from several kidney diseases and can also occur with illnesses such as diabetes and lupus.
Not everyone with chronic kidney disease develops nephrotic syndrome or a blood clot. The relationship depends on the underlying kidney problem and the person's overall health. Kidney disease may be one factor among several that influence clotting risk.
Which kidney conditions are linked to blood clots?
Blood clots are particularly associated with kidney conditions that cause substantial protein loss in the urine. These conditions include:
- Nephrotic syndrome: This condition causes excess protein to pass into the urine and is associated with an increased tendency for blood clots to form.
- Membranous nephropathy: This kidney disease affects the filtering structures and can cause nephrotic syndrome.
- Minimal change disease: This condition damages the kidney's filtering function and can lead to nephrotic syndrome.
- Focal segmental glomerulosclerosis (FSGS): This disease causes scarring in some of the kidney's filtering units and may lead to substantial protein loss.
These conditions do not carry identical risks for every person. The Merck Manual Professional Edition notes that the risk of clotting associated with nephrotic syndrome appears to increase as blood albumin levels fall. The specific kidney disease, its activity, and other medical factors also help determine an individual's risk.
Where can blood clots develop in people with kidney disease?
A clot linked to kidney disease does not necessarily form inside a kidney. It can develop in different blood vessels, and its location affects the possible complications.
Deep vein thrombosis in the legs
Deep vein thrombosis (DVT) occurs when a clot forms in a deep vein, usually in a leg. It can interfere with normal blood flow and sometimes cause part of the clot to break away and travel to the lungs.
According to Mayo Clinic, possible signs of DVT include:
- Swelling in one leg.
- Pain, tenderness, or cramping, often in the calf.
- Skin that feels warmer than usual over the affected area.
- Changes in skin color, including redness or a purple appearance.
These symptoms can occur for reasons other than a blood clot, and some people with DVT have no noticeable symptoms. New, unexplained swelling or pain in one leg warrants prompt medical assessment.
Pulmonary embolism in the lungs
A pulmonary embolism (PE) occurs when a blood clot blocks an artery in the lungs. It often develops when a clot from a deep vein travels through the bloodstream to the lungs. A pulmonary embolism can be life-threatening and requires immediate medical attention.
Seek emergency medical care if you experience sudden shortness of breath, chest pain that worsens with breathing or coughing, coughing up blood, fainting, or sudden severe dizziness. Do not wait for symptoms to improve on their own.
Renal vein thrombosis in the kidney
Kidney disease can also be associated with renal vein thrombosis, a clot in the vein that carries blood away from a kidney. Nephrotic syndrome is an important cause of this condition.
The Merck Manual Consumer Version explains that renal vein thrombosis may develop gradually without obvious symptoms. In some cases, it can cause reduced urine output, blood in the urine, or pain in the back or side below the ribs. A clot can also affect kidney function or, in some cases, contribute to a pulmonary embolism.
Does having chronic kidney disease mean you will develop a blood clot?
No. Chronic kidney disease (CKD) does not automatically mean that a blood clot will develop. The risk varies according to the type of kidney disease, whether nephrotic syndrome is present, the degree of protein loss, and other health circumstances.
Additional factors, such as a previous blood clot, a recent operation, prolonged immobility, or other conditions that affect blood clotting, can also matter. A person with kidney disease may have several contributing risk factors, so clinicians consider the full medical history rather than relying on the kidney diagnosis alone.
It is also important to distinguish between swelling caused by fluid retention and swelling associated with a clot. Kidney disease can cause fluid to collect in the legs, ankles, feet, or other parts of the body. DVT can also cause leg swelling, so the appearance of swelling alone cannot reliably distinguish between the two.
How do doctors check for blood clots in people with kidney disease?
Evaluation depends on the symptoms, the suspected location of the clot, and the person's medical history. A healthcare professional may ask when symptoms began, whether they are changing, and whether there has been recent travel, surgery, illness, or reduced movement. They may also assess existing kidney problems, medications, and any history of blood clots.
Tests may include:
- Blood tests: These can assess kidney function and other relevant health markers. A D-dimer test may help evaluate the possibility of a clot, although an abnormal result does not confirm one.
- Ultrasound: This can examine blood flow in the veins and is commonly used when DVT is suspected.
- Urine tests: These can identify excess protein or blood in the urine and help assess the underlying kidney condition.
- Imaging scans: Depending on the suspected clot, a clinician may recommend CT or MRI-based imaging to examine blood vessels in the lungs, abdomen, or kidneys.
As explained by Mayo Clinic's guidance on DVT diagnosis and treatment, the tests selected depend on the clinical assessment and the likelihood of a clot. Kidney function is particularly relevant when choosing imaging methods and contrast materials, so the medical team can weigh the benefits and risks of each test.
How are kidney-related blood clots treated?
Treatment depends on where the clot has formed, its extent, the person's kidney function, the cause of the clotting problem, and the risk of bleeding. A confirmed blood clot commonly requires anticoagulant medication, often called a blood thinner. These medicines help prevent existing clots from growing and reduce the risk of additional clots while the body gradually breaks down the original clot.
Some kidney-related clots may require specialist treatment or procedures, depending on their location and severity. Clinicians also address the underlying kidney condition when possible. For nephrotic syndrome, care may include treatment directed at the disease causing the excess protein loss, along with management of related problems such as swelling and high blood pressure.
Blood thinners are not appropriate for everyone, and kidney disease can affect medication selection, dosing, and monitoring. Preventive blood thinners are not routinely necessary for every person with CKD or nephrotic syndrome. A healthcare professional determines whether their benefits outweigh the risks in an individual case. Do not start, stop, or change a blood thinner without medical guidance.
Can you reduce the risk of a blood clot with kidney disease?
Risk reduction begins with appropriate care for the underlying kidney condition. Keeping scheduled appointments, completing recommended urine and blood tests, and taking prescribed medicines as directed can help clinicians identify changes that may affect clotting risk.
Depending on your health and mobility, your healthcare team may also recommend regular movement, especially during periods of prolonged sitting or recovery from an illness or operation. Follow any individualized restrictions or mobility advice you have received. Do not take aspirin or other blood-thinning medicines solely to prevent a clot unless a clinician has recommended them for your circumstances.
If you have nephrotic syndrome, ask your kidney specialist whether your current condition increases your risk of blood clots and whether any additional monitoring or preventive measures are appropriate. New leg swelling, persistent unexplained pain, or a change in urine output should be discussed with a healthcare professional promptly. Sudden breathing difficulty, chest pain, or fainting requires emergency assessment.