Microalbuminuria in hypertensive non-proteinuric renal transplant recipients: Role of previous acute rejection episodes and sodium intake

Microalbuminuria (Malb: albuminuria: 30-299 mg/24h) is associated with many cardiovascular parameters (high systolic (SAP) and diastolic (DAP) arteria l pressure, total cholesterol, triglycerides, fasting glucose and body weig ht, low HDL-cholesterol) and may be a marker of cardiovascular and renal ri sk in the general population. Whether MAlb could be an integrated marker of cardiovascular and renal risk in transplant recipients is unknown. Patients and methods: 75 hypertensive non-proteinuric renal transplant reci pients were selected. Antihypertensive medications were stopped for a month prior to the studies. MAlb (on a 24-hour urine collection), cyclosporine t rough levels (CsA-L), fasting glucose and lipids were measured. SAP and DAP were determined with a semi-automatic device. Results: 29 patients (12 W/17M) had normal levels of albuminuria (Nalb: alb uminuria<30 mg/24h) and 46 had MAlb. As compared to Nalb patients, those wi th Malb were younger (M+/-SD : 44.3+/-13 vs 51.2+/-9.7 respectively, p=0.00 9), had higher SAP (152+/-16 vs 146+/-15 mmHg, p=0.09) et DAP (86+/-11 vs. 81+/-10 mmHg, p=0.01). No difference in smoking habits, serum creatinine (1 25+/-27 vs 119+/-28 <mu>mol/L), total-, HDL- and LDL-cholesterol, triglycer ides, fasting glucose, CsA-L (142+/-29 vs 144+/-26 ng/mL), 24h-urine urea e xcretion was observed. History of acute rejection episodes (45.7% vs 17.2%, p=0.01) was more frequent and 24-hour natriuresis (192+/-70 vs 152+/-79 mm ol/24h,p<0.01) was higher in Malb than in NAlb. Conclusion: The determinants of microalbuminuria in renal transplant recipi ents are different from those found in the general population. History of a cute rejection episodes was more frequent in renal transplant recipients wi th Malb than in those with NAlb despite similar renal function, suggesting that Malb may a marker of subclinical renal lesions due to immunological ag gression. The relationship between natriuresis and Malb suggests that sodiu m intake modulates target-organ damage associated with hypertension.