Introduction
Arteriolar nephrosclerosis, also known as hypertensive nephrosclerosis, is a condition affecting the renal tissues as a consequence of uncontrolled hypertension. The increased arterial pressure, when transmitted to the glomerular microcirculation, will result in glomeruli injury and glomerulosclerosis. It serves as one of the most common causes of renal failure. The symptoms may be attributed to renal failure, and the treatment is aimed at controlling elevated blood pressure.
What Is Arteriolar Nephrosclerosis?
Arteriolar nephrosclerosis is a progressive impairment of the kidneys due to poorly controlled blood pressure. Poorly controlled hypertension results in damage to the renal tubules, blood vessels, glomeruli, and interstitium. This, in turn, progresses to end-stage renal disease.
What Is the Difference Between Benign and Malignant Hypertension?
Benign hypertension is a chronic condition with an unknown cause that slowly affects the tissues as a sequelae. Whereas malignant hypertension is a very high blood pressure that occurs rapidly, affecting the organs and causing damage. Arteriolar nephrosclerosis occurs as a complication of benign or chronic hypertension.
What Is the Pathophysiology of Arteriolar Nephrosclerosis?
In patients with uncontrolled high blood pressure, it affects the components of the kidneys, causing nephropathy. In arteriolar nephrosclerosis, there is a narrowing of the renal arteries caused by the deposition of homogenous pink hyaline material along the walls of the blood vessels. This, in turn, reduces the blood flow and oxygenation to the tissues, causing ischemia (insufficient blood supply) slowly affecting the renal tissues, causing interstitial fibrosis (thickening and scarring of renal tubule connective tissue), tubular atrophy (shrinkage and Degeneration of the kidney tubules), and morphological changes in the glomeruli.
What Is Hypertensive Nephrosclerosis?
Hypertensive nephrosclerosis is a condition that results from long-term, uncontrolled high blood pressure (hypertension) that affects the kidneys. Sustained high blood pressure damages the small blood vessels (arterioles) in the kidneys and can lead to kidney structure and function changes. The kidneys are crucial for filtering waste products and excess fluids from the blood to form urine. When hypertension persists over time, the increased pressure can cause injury to the delicate blood vessels in the kidneys, leading to a condition known as nephrosclerosis.
This process can result in the following changes:
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The small arteries (arterioles) in the kidneys may narrow, reducing blood flow to the kidney tissue.
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The walls of the blood vessels in the kidneys may thicken, further restricting blood flow.
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Over time, the kidney tissue may undergo scarring, impairing its ability to function properly.
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The damage to blood vessels can lead to decreased filtration capacity, impacting the kidney's ability to filter waste products and maintain fluid balance.
What Are the Morphological Changes Encountered in Glomeruli Due to Arteriolar Nephrosclerosis?
The glomeruli show three types of morphological changes it includes;
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Obsolescent Glomeruli - Partially or fully collapsed glomerular tuft with the extracellular material in the bowman's capsule.
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Solidified Global Glomerulosclerosis - The glomeruli are completely replaced by collagen, and the glomerular tuft is expanded.
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Segmental Glomerulosclerosis - In which, the part of the glomeruli undergoes sclerosis (abnormal hardening or thickening of tissues).
How Does Arteriolar Nephrosclerosis Progress to Kidney Failure?
The above-said alterations in the glomeruli and periglomerular sclerosis (scarring around the glomeruli) will affect the functional nephrons, reducing the functioning capacity of the kidneys, which subsequently progresses to kidney failure. Two proposed pathogenesis for kidney failure through hypertensive nephrosclerosis are:
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Glomerular Sclerosis - The blood flow to the kidneys is decreased due to the narrowing of the renal arteries; thus, the kidneys shrink and lose function, causing kidney failure.
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Glomerular Hypertension and Hyperfiltration - The glomeruli undergo sclerosis and renal tissue ischemia due to chronic hypertension. On the other hand, the unaffected nephrons try to compensate for the functional loss and do more work to filter the waste products, leading to renal failure.
What Is the Epidemiology of Arteriolar Nephrosclerosis?
Arteriolar nephrosclerosis is one of the most common causes of kidney failure. 17 to 25 percent of the patients under dialysis are affected by this condition due to uncontrolled hypertension. Studies report that the black population is highly susceptible to arteriolar nephrosclerosis.
Who Is at High Risk for Arteriolar Nephrosclerosis?
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High blood pressure.
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Old age.
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Pre-existing kidney disease.
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Diabetes.
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Obesity.
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Chronic inflammation.
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Smoking.
What Are the Symptoms of Arteriolar Nephrosclerosis?
Symptoms may be attributed to progressing renal failure. It includes:
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Tiredness.
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Lethargy.
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Vomiting.
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Nausea.
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Pruritus (itching all over the body).
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Loss of appetite.
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Confusion.
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Proteinuria (presence of protein in the urine).
How Is Arteriolar Nephrosclerosis Diagnosed?
The diagnosis of this condition is based on the following:
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Clinical History: A thorough clinical history of the symptoms associated with the condition and the elevated blood pressure is a major clue in diagnosing arteriolar nephrosclerosis.
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Monitoring Blood Pressure: The patient's blood pressure levels are elevated.
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Ultrasound of Kidney: Ultrasonographic examination of the kidney would reveal the kidney tissues' deterioration due to sclerosis and reduced kidney size due to reduced blood supply and tissue ischemia.
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Kidney Biopsy: A microscopic examination of the kidney tissues would reveal sclerosis of the glomeruli. The presence of homogenous pink hyaline material along the walls of the blood vessels causes the thickening of the blood vessels. A biopsy also shows the capillary basement membrane's thickening, the capillary lumen's collapse, and periglomerular scarring.
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Blood Examination: A blood examination would reveal signs of decreased kidney function, such as elevated serum creatinine and urea levels.
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Urine Examination: Examination of urine would reveal the presence of protein in the urine and the tiny tube-shaped particles called urinary casts in the urine sediments.
How Is Arteriolar Nephrosclerosis Managed?
The prime goal of treatment for arteriolar nephrosclerosis is to control elevated blood pressure levels. Followed by correcting the complications:
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ACE Inhibitors - Angiotensin-converting enzyme inhibitors can be prescribed to reduce high blood pressure levels.
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ARB Drugs - Angiotensin II receptor blockers would also help control hypertension.
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Combination Drugs - A combination of ACE inhibitors and ARB can be given in cases with severely high blood pressure levels.
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Calcium Channel Blockers and Thiazide Diuretics - Can also be given to reduce hypertension.
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Chronic Kidney Disease - Kidney disease caused by ischemia can be managed by restricting salt and fluid intake.
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End-Stage Renal Disease - In such cases, dialysis is indicated, or kidney transplantation is the treatment of choice.
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Non-pharmacological Measures- Other general measures such as:
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Regular exercise.
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Weight loss.
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Salt restrictions.
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Limited water intake.
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This would help control blood pressure and reduce the load on the kidneys.
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What Is the Prognosis of Arteriolar Nephrosclerosis?
The prognosis of this condition largely depends on blood pressure control and the amount of kidney damage. As renal failure develops slowly, the prior treatment would help prevent permanent kidney damage. Studies state that only one to two percent of people develop renal failure after five to ten years of arteriolar nephrosclerosis.
Conclusion
Arteriolar nephrosclerosis is a blood vessel disorder of the kidney caused by chronic, uncontrolled hypertension. It is reported to be one of the most common causes of renal failure. The prognosis is reported to be good, with prompt management of hypertension.
