8. Hypertensive nephrosclerosis

Question 1

what is the difference between benign hypertensive nephrosclerosis and malignant nephrosclerosis

Answer 1

BHN = chronic kidney disease caused by hypertension (only develops in minority of hypertensive Ps), resulting in chronic renal failure

MN = acute kidney injury caused by sudden large increase in BP

Question 2

explain why hypertensive nephrosclerosis results in kidney damage

Answer 2

1. vascular changes to renal arteries and arterioles
   
   • fibroelastic intimal thickening… narrowing of lumen
   • hyalinosis of afferent arteriolar walls… decreased blood flow… chronic low-level renal ischaemia… atrophy
2. glomerular changes (secondary to ischaemia from vascular changes)
   
   • wrinkling of glomerular tuft
   • glomerulosclerosis (patchy)

Question 3

how should benign hypertensive nephrosclerosis be managed

Answer 3

1. good BP control

2. ACEi or AngII R blockers if albuminuria

Question 4

what is the difference between hypertensive nephrosclerosis and renal artery stenosis

Answer 4

BHN:

• hypertension precedes renal disease by long timeframe
• less rapid decline in GFR
• generally preceded by LV hypertrophy and hypertensive eye disease

RAS:

• hypertension more acute and refractory to treatment
• more rapid decline in GFR
• evidence of atherosclerosis elsewhere
• acute worsening with RAAS blockade

Question 5

why does a sudden increase in BP damage the kidney (malignant nephrosclerosis)

Answer 5

acute large increase in BP… arteriole endothelium damage - fibrinoid necrosis… ischaemia… RAAS activation… AKI.

Results in:

• haematuria
• microangiopathic haemolytic anaemia (due to shearing of RBCs by platelets on damaged endothelial cells)