Renal Infarction - All You Need to Know

Introduction:

The kidneys are a pair of excretory organs that help to filter waste from the body. When the blood supply to the kidney is compromised, the condition is called renal infarction. It is usually an under-reported condition and is often overlooked. The similarity in clinical presentation in many other medical conditions mainly causes this. The interruption of the blood supply can be in a part of the kidney, a kidney as a whole, or both kidneys. It is a very uncommon scenario and a condition often misdiagnosed or diagnosed late.

What Is Renal Infarction?

Renal infarction is uncommon when the renal artery or its branches fail to supply sufficient blood to the kidneys. This is often misdiagnosed or diagnosed late due to the similarity in clinical presentation with many other medical conditions. This can cause permanent damage to the renal tissues.

What Is Meant by an Atrophic Kidney?

When the kidney is smaller than its normal size, then it is called an atrophic kidney. This condition can occur when a part of the kidney does not develop, making the kidney smaller in size. This does not require any special treatment.

What Are the Causes of Renal Infarction?

The common causes of renal infarction can include:

• Atrial fibrillation is a heart condition caused by irregular heart rhythm, often causing clots in the heart.

• A thrombus originates from the heart, and a clot in the blood vessels is called a thrombus.

• Coagulation disorders disturb blood clotting after a wound or injury.

• Vasculitis is when the blood vessels become inflamed; the condition is called vasculitis. It can thicken the blood vessels.

• Connective tissue disorders.

• Valvular endocarditis is when germs enter the valves of the heart and cause inflammation is called valvular endocarditis.

• Atherosclerosis of the aorta is when plaque accumulates in the aorta of the heart; the condition is called atherosclerosis of the aorta.

• Atherosclerosis of the renal artery is the plaque accumulation in the renal artery called atherosclerosis of the renal artery.

• An aortic aneurysm is a bulge occurring in the heart's main blood vessel is called an aortic aneurysm.

• Aortic dissection is when blood enters the aorta due to a tear in one of its layers, causing a false lumen containing blood; the condition is called aortic dissection.

• Renal artery dissection is when blood enters the renal artery due to a tear in one of its layers, causing a false lumen containing blood, the condition is called renal artery dissection).

• Fibromuscular dysplasia is a condition that causes the narrowing down of the blood vessels along with aneurysms in some parts is called fibromuscular dysplasia.

• Smoking.

• Trauma.

• Iatrogenic causes are accidentally caused by a doctor during surgical procedures like angiography.

• Malignant hypertension is a condition when there is a sudden hype in the blood pressure in an artery that can be harmful to the related organs is called malignant hypertension.

• Renal vein occlusion or thrombosis is a clot formation in the renal vein, or its branches is called renal vein thrombosis.

• Torsion of a kidney that was transplanted rotates around its vascular pedicle.

What Are the Signs and Symptoms of Renal Infarction?

The typical clinical presentation of a renal infarction includes;

• Abdominal pain.

• Nausea and vomiting.

• Fever.

• Hematuria (presence of blood in urine).

What Are the Differential Diagnosis of Renal Infarction?

• Renal Colic: The pain associated with a stone in the kidney is termed renal colic.

• Nephrolithiasis: The presence of stones in the urinary tract is generally called nephrolithiasis.

• Pyelonephritis: An infection in the kidney is termed pyelonephritis.

How Is Renal Infarction Diagnosed?

• Laboratory Evaluation: Laboratory results show leukocytosis, hematuria, increased CRP (C-reactive protein), and LDH (lactogen dehydrogenase). An elevation in the LDH levels indicates cell necrosis and can rise to five to six times the normal value. Other possible laboratory results can include an abnormal increase in creatinine level and a decrease in the GFR (glomerular filtration rate). A potentially abnormal elevation in the creatinine levels indicates a large area of necrosis or bilateral necrosis. Proteinuria can be seen in some cases.

• Imaging Tests: A non-contrast CT (computed tomography) of the abdomen and pelvis is done to eliminate urolithiasis and pyelonephritis. If non-contrast CT is not helpful, a contrast-enhanced CT should be done to rule out renal infarction. The standard test for a suspected renal infarction case is the contrast-enhanced CT.

• Renal CT Arteriography: A renal CT arteriography is the gold standard for investigating renal infarction. It helps to make a definitive diagnosis and helps to decide on the mode of treatment as well. Other confirmatory tests can include magnetic resonance imaging with gadolinium contrast excretion and DMSA (dimercaptosuccinic acid) radioisotope scans.

• Color Doppler Scan: A color Doppler scan can show a reduced or absent blood flow to an organ.

How Is Renal Infarction Treated?

The treatment for renal infarction is broadly classified into four categories.

• Catheter-directed thrombolysis.

• Systemic thrombolysis.

• Anticoagulation.

• Surgery.

The patients are also assessed if they would benefit from revascularization procedures (procedures that help to restore the blood supply) after considering the duration of the decrease in blood supply, the area of necrosis, etc. When the infarct is small, the cause is found and rectified, which helps to bring the kidney back to normal condition.

Catheter-directed thrombolysis is done when there is proximal or bilateral renal artery occlusion. When catheter-directed thrombolysis is not available, systemic thrombolysis is done. The risk of systemic bleeding is high in this type of thrombolysis.

Anticoagulation therapy is indicated in patients who have had a renal infarction for a long time or in patients whose revascularization procedures were unsuccessful. It is also used in patients with atrial fibrillation and hypercoagulable disorders. Surgery is preferred when the renal infarction has occurred due to trauma or injury or an aortic dissection that extends to the renal artery.

What Are the Differential Diagnoses of Renal Infarction?

An important differential is hypoenhancement caused by infections such as lobar nephronia or pyelonephritis. In these conditions, the cortical rim is absent and is present with inflammatory or infectious symptoms.

Conclusion:

Renal infarction is an easily missed diagnosis due to its similarity with many other medical conditions. It can be suspected when a patient presents with abdominal pain with blood in the urine (hematuria) without signs of urinary tract infections. The prognosis of the condition is found to be good if identified and treated early. The prognosis also depends on the duration of ischemia, the area of necrosis, the presence of existing kidney disease, the presence of a thrombus in other organs, etc.