Sodium renal artery stenosis

Under conditions in which arterial pressure or body fluid volumes are sensed as subnormal, the renin-angiotensin system will be activated and plasma renin activity and angiotensin II levels will be elevated. These conditions include dietary sodium restriction or sodium depletion (such as during diuretic therapy), renal artery stenosis, and congestive heart failure. In each case, fluid and sodium will be retained until the pressure and volume are again sensed as normal. Note... 

In one of the earliest reports it was shown that not only captopril but also minoxidil caused GFR to decrease in a patient with a transplant renal artery stenosis [23], suggesting that it was the fall in blood pressure itself, which caused the reduced GFR. However, in other studies it was found that GFR decreased only during treatment with captopril and enalapril [24] whereas a fall in blood pressure during sodium nitroprusside [25] or minoxidil [26, 27], which do not directly interfere with the renin-angiotensin system, did not result in a decline in GFR. Furthermore, studies from Anderson et al. indicated that during infusion of... 

As predicted by our understanding of the basic physiology, the fall in filtration after ACEI in a patient with renal artery stenosis is dependent upon the prevaihng sodium status of the patient [27,32-34]. The critical role of sodium balance in this fall in GFR during ACEI has been nicely documented in a case report by Hiicik [34], who showed that GFR decreased more markedly in a patient with a transplant renal artery stenosis when captopril was given in a sodium depleted as compared to a sodium replete situation (Table 1). Moreover, Andreucd et al. reported that intravenous infusion of saline could reverse the fall in creatinine... 

Table 1. The effect of sodium intake on the renal response to captopril in a patient with a transplant renal artery stenosis.

Used as a screening test, an elevated plasma renin activity after furosemide stimulation or when correlated with urinary sodium excretion can suggest renal artery stenosis as the cause of the hypertension (Figure 51-18). If there is arteriographic evidence for renal artery stenosis, measurement of plasma renin in specimens obtained from selective... 

The interaction between NSAIDs and lithium is well established, although the incidence is unknown. The increase in serum-lithium levels appears to vary between the different NSAIDs and also between individuals taking the same NSAID (see Table 31.1 , (p.ll27)). Factors such as advanced age, impaired renal function, decreased sodium intake, volume depletion, renal artery stenosis, and heart failure increase the risk. 

---