Hypertensive Nephropathy

Overview
  • Hypertensive Nephrosclerosis refers to the renal pathological changes that occur due to long-term presence of hypertension. Given that long-standing hypertension is typically seen in the elderly, changes of hypertensive nephrosclerosis are usually observed in this demographic.
Morphology
  • Overview
    • The morphology of hypertensive nephrosclerosis depends on the severity of hypertension. Most individuals display "Benign Nephrosclerosis"; however, in those with malignant hypertension, changes of "Malignant Nephrosclerosis" may supervene.
  • Benign Nephrosclerosis
    • Benign nephrosclerosis is characterized by "Hyaline Arteriosclerosis" of the renal arterioles and involves a deposition of a hyaline substance in arteriolar wall that narrows the luminal diameter. The remainder of the kidney, including the glomeruli, nephrons, and renal interstitium all show diffuse atrophy with some attendant fibrosis.
  • Malignant Nephrosclerosis
    • Malignant Nephrosclerosis is characterized by small hemorrhage]s from surface vessels can give the kidneys a characteristic "Flea-bitten" appearance. Smaller renal vessels such as arterioles display fibrinoid necrosis and inflammatory cells may be present, yielding a picture of "Necrotizing Arteriolitis". Larger renal vessels such as renal interlobular arteries often display a concentric proliferation of the vascular wall's cellular elements, termed "Hyperplastic Arteriolosclerosis". This gives interlobular arteries an "onion-skin" appearance and can dramatically narrow their lumen.
Pathogenesis
  • Benign Nephrosclerosis
    • Benign nephrosclerosis can be thought of as the renal manifestation of general changes associated with arteriosclerosis that affect any tissue's arterioles due to long-standing hypertension. In the kidneys, narrowing of renal arteriolar diameter as a consequence of hyaline arteriosclerosis reduces downstream blood flow. This results in chronic low-level ischemia of the renal tissue, over time manifesting as atrophy. It is important to point out that benign nephrosclerosis occurs as a result of the presence of long-term hypertension of any etiology. Given that many renal diseases cause hypertension (e.g. etiologies of nephritic syndrome), the morphological changes of benign nephrosclerosis often occur on top of the pathological changes observed in these hypertensive renal diseases.
  • Malignant Nephrosclerosis'
    • The above morphological features are adaptive responses of the renal blood vessels to extremely high arterial pressures. These renal morphological adaptation probably contribute to the pathogenesis of malignant hypertension.
Clinical Consequences
  • At one time the morphological changes of benign nephrosclerosis were thought to be of little clinical consequence. However, in nearly 5% of hypertensive patients, long-standing elevation of arterial pressure appears to be the cause of chronic renal failure. Although this occurs in only a fraction of hypertensive individuals, the enormous incidence of hypertension means that hypertensive nephropathy is a major cause of chronic renal failure.