Hypertensive nephropathy, also known as hypertensive nephroangiosclerosis, refers to kidney damage caused by chronic arterial hypertension. The interaction between blood pressure and renal function is complex: hypertension can be both a cause and a consequence of kidney diseases, establishing a vicious cycle that accelerates the progression of organ damage.
Arterial hypertension causes structural alterations in the renal vessels from the earliest stages. Chronic elevation of pressure induces thickening of afferent arterioles, with collagen deposition and fibrosis of the vascular wall. This process, known as nephroangiosclerosis, leads to narrowing of the vascular lumen, resulting in reduced perfusion of the glomeruli and consequent tissue hypoxia.
Initially, hypertensive nephropathy is asymptomatic, and renal alterations may only be detected through laboratory tests. Microalbuminuria represents the first sign of glomerular damage and, if hypertension is not adequately treated, evolves into proteinuria, indicating irreversible impairment of the renal filtration barrier.
Hypertensive nephropathy is characterized by a series of histological and functional alterations that develop in response to elevated blood pressure.
Structural changes involve the renal tissue at both vascular and glomerular levels, while functional consequences manifest as a progressive compromise of the kidney's filtration capacity.
The histological alterations include:
Focal and segmental glomerulosclerosis: some glomeruli undergo sclerosis and obliteration, while the remaining glomeruli undergo compensatory hypertrophy to maintain the filtration function.
Arteriolar thickening and interstitial fibrosis: the walls of the renal arterioles become thickened and less elastic, reducing blood flow and contributing to renal tissue distress.
The reduction in the number of functioning nephrons leads to a deterioration of renal function with progressive impairment of filtration capacity and possible evolution towards chronic kidney disease.
Clinical Manifestations
In its early stages, hypertensive nephropathy is silent and is often diagnosed incidentally during routine check-ups, with the finding of proteinuria or altered serum creatinine.
As renal damage progresses, the following may occur:
Resistant arterial hypertension: renal impairment contributes to the activation of the renin-angiotensin-aldosterone system, further aggravating blood pressure.
Reduced creatinine clearance: indicative of progressive renal insufficiency.
Dependent edema and fluid retention: due to glomerular dysfunction with impaired sodium balance.
Electrolyte imbalances: particularly hyperkalemia in advanced stages of the disease.
In advanced cases, hypertensive nephropathy can lead to end-stage chronic kidney disease (ESRD), requiring dialysis or kidney transplantation.
Diagnosis
The diagnosis of hypertensive nephropathy is based on several diagnostic tests. Blood chemistry tests show an increase in serum creatinine and a reduction in glomerular filtration rate, both indicators of progressive deterioration of renal function. Urinalysis can reveal microalbuminuria in the early stages and proteinuria in more advanced cases, both signals of more significant renal damage.
Renal ultrasound allows for the assessment of renal morphology, highlighting a reduction in kidney size and increased vascular resistance, a sign of advanced nephroangiosclerosis. Renal biopsy, although rarely indicated, may be performed in cases where the diagnosis is uncertain or in patients with atypical disease progression.
Treatment
Treatment is based on strict blood pressure control. Maintaining optimal blood pressure values is the most effective strategy to prevent the progression of renal damage and reduce the risk of complications.
Other strategies aim to protect the kidney and preserve its function. Proteinuria is an indicator of renal damage and a predictor of disease progression. ACE inhibitors and sartans, used in the treatment of hypertension, also have an antiproteinuric effect independent of their antihypertensive action, as they reduce intraglomerular pressure and counteract damage mediated by the renin-angiotensin system.
In patients with persistent proteinuria, aldosterone antagonists, such as eplerenone and spironolactone, may be added to reduce renal fibrosis and vascular remodeling. Another effective treatment is represented by SGLT2 inhibitors, including dapagliflozin and empagliflozin, used for both diabetes and hypertensive nephropathy, as they improve renal protection by reducing intraglomerular pressure and proteinuria.
Diet also plays a fundamental role. Sodium restriction (< 2 g/day) reduces fluid retention and pressure overload. In advanced cases, a low-protein diet helps reduce the metabolic load on the remaining nephrons, slowing the progression of renal failure.
When renal function (GFR) drops below 15% (end-stage), renal replacement therapy becomes necessary. At this stage, peritoneal dialysis can be used, allowing blood purification through the peritoneum with home procedures, or hemodialysis, an extracorporeal treatment that removes metabolic waste and excess fluids. In eligible patients, kidney transplantation represents the definitive solution, improving both quality of life and long-term prognosis.
Conclusion
Hypertensive nephropathy is one of the main causes of chronic kidney disease and can progress silently to advanced stages. Early and aggressive blood pressure control is crucial to prevent disease progression. Regular monitoring of renal function in hypertensive patients allows for early detection of nephropathy signs and the implementation of targeted therapeutic strategies to preserve renal function.
References
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