Renal artery stenosis in kidney transplants: assessment of the risk factors.

BACKGROUND: Transplant renal artery stenosis (TRAS) is an important cause of hypertension and renal allograft dysfunction occurring in kidney transplant recipients. However, conflicting predisposing risk factors for TRAS have been reported in the literature. OBJECTIVE: The aim of the present study was to assess the potential correlation between possible risk factors and TRAS in a group of living donor renal transplant recipients 1 year after the renal transplantation. METHODS: We evaluated the presence of renal artery stenosis in 16 recipients who presented with refractory hypertension and/or allograft dysfunction 1 year after renal transplantation. Screening for TRAS was made by magnetic resonance angiography and diagnosis was confirmed by conventional renal angiography. Age, gender, history of acute rejection, plasma lipid profile, serum creatinine, blood urea nitrogen, serum uric acid, calcium phosphate (CaPO4) product, alkaline phosphatase, fasting blood sugar, hemoglobin, and albumin were compared between the TRAS and non-TRAS groups. RESULTS: Of 16 kidney transplant recipients, TRAS was diagnosed in three patients (two men and one woman). High levels of calcium, phosphorous, CaPO4 product, and low-density lipoprotein (LDL) cholesterol were significantly correlated with the risk of TRAS 1 year after renal transplantation (P < 0.05). Serum level of uric acid tended to have a significant correlation (P = 0.051). CONCLUSION: Correlation between high CaPO4 product, LDL cholesterol, and perhaps uric acid and TRAS in living donor renal transplant recipients 1 year after renal transplantation might suggest the importance of early detection and tight control of these potential risk factors.

Hypertension and renovascular disease: follow-up on 100 renal vein renin samplings.

The clinical value of renal vein renin sampling (RVRS) as a prognostic tool in the treatment of renovascular hypertension was evaluated. One hundred consecutive patients were included over a 4-year period of time. About half of the patients (49%) were treated interventionally by PTRA (21%), nephrectomy (20%), or vascular surgery (8%). Seven patients (15%) were cured and 15 (32%) had improved (reduction in antihypertensive medicine) after 6 months follow-up, whereas three patients (6%) were cured and 12 (26%) improved after 3-4 years follow-up. Thus, the number of patients cured or improved is comparable with the results from our department reported 20 years ago. However, in the present report, more than twice as many patients were enrolled, leading to double costs. Different indices of lateralisation of the renin generation were calculated for the use in cases of a shrunken kidney (functional share < or =15%). None of the indices clearly discriminated between the patients who did benefit from intervention, and those who did not. The only positive finding was that a peripheral renin concentration lower than 8 mlU/l predicted no effect of intervention, which might lead to the exclusion of 11% of the patients before entering the diagnostic programme. We conclude that the RVRS demands a very restrictive referral pattern if it should be of prognostic value for the blood pressure outcome after intervention. No indices of lateralised renin concentrations proved high predictive value. However, a peripheral renin concentration low in the normal range seems useful as an indicator of no benefit from intervention.

Renal artery stenosis with severe hypertension. A rare case with detailed assessment of renin-angiotensin system before and after development of lesion.

The rare opportunity arose to assess in detail the renin-angiotensin system before and after the development of a renal artery stenosis with severe hypertension. Peripheral plasma concentrations of renin, angiotensin II, and aldosterone were known to be normal before the development of renal artery stenosis, and there were no lateralising features on renal vein sampling. Acute hypertension associated with very high peripheral plasma concentrations of renin and angiotensin II, and with pronounced lateralisation on renal vein sampling followed the development of acute unilateral renal artery stenosis. These measurements all returned to normal after nephrectomy, conforming with the pattern of changes previously established only in experimental animals.