A “kidney stroke” is a term commonly used to describe a serious medical condition involving a sudden disruption of blood flow to the kidneys. While not a formal medical diagnosis, it conveys the urgency and potential for damage. Such an interruption can lead to injury to the kidney tissue, requiring prompt medical attention to minimize potential long-term complications. Understanding this condition is important for recognizing its signs and seeking timely care.
What is a Kidney Stroke?
Medically, a “kidney stroke” is known as a renal infarction, which occurs when the blood supply to part or all of a kidney is blocked. This blockage prevents oxygen and nutrients from reaching the kidney tissue, leading to cellular damage or death. The kidneys rely on a steady flow of oxygen-rich blood, delivered by the renal arteries, to perform their functions of filtering waste and maintaining fluid and electrolyte balance.
A complete or partial occlusion of the main renal artery or its smaller branches can cause this abrupt disruption. When blood flow is severely reduced or stopped, the affected kidney tissue begins to die, impairing the kidney’s ability to filter waste and regulate substances in the body. This acute event differs from chronic kidney disease, which typically develops slowly over time due to conditions like high blood pressure or diabetes.
Why Kidney Strokes Occur
Renal infarction frequently results from blood clots that originate in other parts of the body, most often the heart or the aorta. These clots can travel through the bloodstream and lodge in the renal arteries, obstructing blood flow. The formation of a clot directly within a renal artery is a less common but still significant cause.
Several underlying conditions and risk factors can increase a person’s susceptibility to renal infarction. Cardiovascular diseases, particularly atrial fibrillation, are common contributors, as they can lead to the formation of blood clots that may travel to the kidneys. Other causes include renal artery injury, such as from trauma or dissection.
Conditions like vasculitis, which involves inflammation of blood vessels, and fibromuscular dysplasia, a disorder causing abnormal narrowing of arteries, can also reduce blood flow and contribute to infarction. Risk factors such as high blood pressure, diabetes, and certain genetic conditions that cause a hypercoagulable state, meaning the blood clots more easily, also raise the likelihood of a kidney stroke.
Signs of a Kidney Stroke
The symptoms of a kidney stroke often appear suddenly and can be intense. The most common initial symptom is severe flank pain, which is pain located in the side or back, just below the ribs. This pain can be accompanied by nausea and vomiting.
Some individuals may also experience a fever, indicating an inflammatory response, though this is not always present. Other possible symptoms include blood in the urine, either visible or microscopic, and an abrupt increase in blood pressure. In some instances, particularly with smaller infarcts, symptoms can be subtle or even absent, making diagnosis challenging as they might be mistaken for other conditions like kidney stones or infections.
Confirming and Treating a Kidney Stroke
Diagnosing a renal infarction involves clinical evaluation and specific tests. Healthcare providers assess symptoms, focusing on the sudden onset and severity of flank or abdominal pain, as well as any associated nausea, vomiting, or changes in urine output. A physical examination often reveals tenderness in the flank area and elevated blood pressure.
Blood tests evaluate kidney function and detect signs of tissue damage. Elevated levels of lactate dehydrogenase (LDH), an enzyme released when tissue is damaged, are commonly observed in renal infarction. Kidney function tests, such as creatinine and blood urea nitrogen (BUN) measurements, can indicate impaired kidney function. Imaging studies are important for confirmation; a contrast-enhanced CT angiography is considered the definitive test, showing areas of the kidney that are not receiving blood flow. Magnetic resonance imaging (MRI) or Doppler ultrasound can also be used, especially if CT angiography is not suitable.
Treatment approaches for renal infarction aim to restore blood flow and prevent further damage. Anticoagulants are often administered promptly to prevent new clots from forming and to stop existing clots from growing larger. In cases diagnosed within hours of symptom onset, thrombolytic therapy may be considered. This involves administering medications, such as tissue plasminogen activator (tPA), to dissolve the clot. In some situations, surgical interventions or angioplasty, which involves widening the narrowed artery, may be necessary to remove the blockage and restore blood flow.
What Happens After a Kidney Stroke?
The outcome following a kidney stroke varies depending on the extent and duration of the blood flow interruption, and the promptness of diagnosis and treatment. Full recovery of kidney function is possible, especially with early intervention. However, permanent kidney damage, including acute kidney injury or chronic kidney disease, can occur if the blood supply is severely compromised or prolonged.
Managing underlying risk factors, such as high blood pressure and heart conditions like atrial fibrillation, is important to prevent recurrence. Long-term anticoagulation therapy may be necessary for individuals with ongoing risks for blood clot formation. Regular follow-up care, including monitoring kidney function and blood pressure, helps manage any residual damage and supports overall kidney health.