hey...thanx...I couldn't get why it s unresponsive to ACEi or ARBs...can someone please explain...

 

Yes, I am wondering about this question too. ARB's should respond?

 

why increase renin??

 

Because renal artery stenosis causes ischemia in the kidneys, so this leads to activation of RAA System.

 

Renovascular hypertension

bilateral renal art stenosis can also be seen in elderly people.
as we know GFR is inversely related to serum creat..meaning an increase in serum creat means a decrease in creat clearance=GFR= renal failure
which is only seen when both kidneys are affected

a patient with bilateral renal art stenosis the GFR is maintained by AII mediated vasoconstriction of efferent arteriole. giving an ACEi/AIIi disregulate this mechanism leading to decreased GFR. further causes deminishing of RAAS leading to decreased aldosterone which promotes the hyperkalemia (also due to ARF).

note that there are more causes of ARF after initiating ACEi : CHF, PKD, bilateral hydronefrose, glomerular disease with intrarenal nefrosclerose.