Brief overview
- Symptoms: Flank or abdominal pain, nausea, vomiting, fever, elevated blood pressure; sometimes asymptomatic.
- Treatment: Mostly medicinal with painkillers, blood thinners, antihypertensives; lysis or surgical therapy less common
- Diagnosis: Doctor-patient interview, physical examination, blood and urine tests, ultrasound or X-ray
- Course of disease and prognosis: With early treatment, good prognosis, late effects such as high blood pressure or kidney weakness possible, depending on the occluded blood vessel of the kidney and time of diagnosis, rarely leads to acute kidney failure
What is a renal infarction?
Thanks to good preventive measures, renal infarction is a rather rare event. In a few cases, a renal infarction leads to acute kidney failure.
Complete renal infarction and partial renal infarction
Depending on the extent, doctors distinguish between complete renal infarction and partial renal infarction:
- Complete renal infarction: Here, the end artery is completely blocked.
In a complete renal infarction, the affected kidney tissue perishes after only one to two hours. This means that the tissue dies due to the lack of oxygen and nutrients; doctors refer to this as necrosis. If the renal vessel is only partially occluded or if there is adjacent blood flow (collateral blood flow), it is possible to save the kidney. It is then important to restore blood flow within 24 to 48 hours.
A renal infarction results from the occlusion of a renal artery or a renal vein.
If a renal artery is affected, it is a so-called ischemic renal infarction. Depending on the location of the blockage, doctors distinguish between different forms. These are:
- Wedge-shaped renal infarction: results from occlusion of the smallest arteries (arteriae interlobulares).
- Renal infarction of the half or whole kidney: results from stenosis or occlusion in the renal artery trunk
In hemorrhagic renal infarction, a renal vein is affected by occlusion. In this case, blood outflow is blocked, resulting in blood stasis. The reflow of fresh oxygenated blood is no longer possible.
What are the symptoms of a renal infarction?
In some cases, a small renal infarction remains asymptomatic. The renal infarction therefore often goes unnoticed and is only noticed due to poor kidney function.
- Visual field defects
- Muscle pain
- Acute inflammation of the pancreas (pancreatitis)
- Splenic infarctions
What is the treatment for a renal infarction?
In most cases, the treatment of renal infarction is conservative, meaning medicinal, rather than surgical or invasive. This treatment is usually based on three pillars:
- Blood thinning
- Pain relief
- @ Reduction of high blood pressure
Even if both kidneys are affected and temporary dialysis (artificial blood washing) is necessary, the kidney usually recovers considerably after drug treatment.
Lysis therapy and surgery
In rare cases, doctors perform surgery or lysis therapy to treat renal infarction.
During surgery, doctors try to remove the thrombus or embolus. However, such an operation always carries a high risk and is therefore very rarely used in practice.
How is a renal infarction diagnosed?
Due to the narrow time window, it is nevertheless only rarely possible to initiate the appropriate treatment in good time. Moreover, since renal infarction is sometimes without symptoms as well as characterized by complaints of other kidney diseases, diagnosis is often not easy and takes a long time.
Medical history
If the diagnosis is unclear, the physician first takes a detailed medical history (anamnesis). To do this, doctors ask the following questions, among others:
- Where exactly do you have the pain?
- Do you suffer from vascular diseases such as vasculitis?
- Do you have a heart defect or cardiac arrhythmia?
- Do you have a known aortic aneurysm?
- Have you ever had surgery? If so, when?
- Have you ever had a cardiac catheterization?
- Do you have diabetes mellitus (diabetes)?
Physical examination
The doctor also looks for signs that may indicate embolisms. Embolisms are blood clots that are swept from one place (such as the heart) in the body into a blood vessel elsewhere in the body and then block it. Palpation of the pulses also provides a possible indication of inadequate blood flow. In addition, the doctor usually measures blood pressure to find evidence of high blood pressure.
Blood and urine tests
- White blood cells (leukocytosis)
- C-reactive protein (CRP)
- Serum creatinine
- Lactate dehydrogenase (LDH)
LDH can be detected when cells die in the body, as is the case with renal infarction. Extensive occlusion leads to a significant increase in LDH, such as occurs after a heart attack.
Imaging examinations
Ultrasound examination (sonography)
Reduced blood flow to the kidney can be most easily and gently visualized by ultrasound examination (sonography). The renal arteries are usually easily visible on ultrasound. High-grade renal artery changes and occlusions can be detected by ultrasound in most cases.
Angiography
To confirm the diagnosis of “renal infarction,” doctors sometimes consult angiography. This is an X-ray examination of the blood vessels of the kidney.
Exclusion of other diseases with similar symptoms
A sudden onset of flank pain does not necessarily mean a renal infarction. In some cases, renal colic or inflammation of the renal pelvis are behind it instead.
The frequently diagnosed spinal syndrome also sometimes causes flank pain. Doctors understand spinal syndrome as all acute and chronic pain conditions of the spine.
Visible blood in the urine is a symptom that is not unique to renal infarction. Many other diseases of the kidney or the urinary tract, as well as injuries in this area, cause similar symptoms.
How does a renal infarction develop?
Renal infarction caused by an embolism
Most commonly, an embolism causes a renal infarction. The blood clot (embolus) usually comes from the heart and eventually gets stuck in a small renal artery and blocks it. Specifically, the embolus comes from different parts of the heart or body:
- From the left atrium of the heart (especially in atrial fibrillation).
- From the aorta: Inflammatory changes in the blood vessels, so-called arteriosclerotic plaques, detach themselves in some cases during interventions on the aorta (such as a cardiac catheterization) or during vascular plastic surgery. They usually block both renal vessels.
In rare cases, cholesterol emboli are the cause of renal infarction. In this case, cholesterol crystals clog the renal vessels and prevent the blood supply to the kidney.
Renal infarction due to thrombosis
Risk factors for renal infarction
Many patients with renal infarction have cardiovascular risk factors. Cardiovascular means affecting the cardiovascular system. Therefore, it is important to identify such risk factors as well as inherited predispositions that favor vascular occlusion in a timely manner. In summary, risk factors include the following:
- Vascular diseases: Inflammatory rheumatic disease of the vessels (vasculitis) such as panarteritis nodosa, arteriosclerosis, aortic aneurysm, circulatory shock, diabetes mellitus.
- Connective tissue diseases (collagenoses) such as lupus erythematosus
- Vascular injuries caused by surgery or an X-ray examination (angiography) of the renal vessels
What is the prognosis of a renal infarction?
Moreover, it is possible that additional emboli occurring outside the kidney and the underlying disease responsible may further worsen the health condition.
If the renal infarction is a cholesterol embolism, the prognosis is generally poor. In most cases, patients then require regular dialysis.