Objective: Primary aldosteronism (PA) is associated with vascular end organ damage. We evaluated the newly established German Conns Register for evidence of renal impairment and compared the data with renal function from hypertensive subjects from an epidemiologic cohort.
Methods: The registry was founded in 2006 and has at present 7 participating centres in 5 locations. Data are entered in a central electronic database. Up to July 2007 555 patients were enrolled and matched for age, sex and BMI in a 1:1 ratio with hypertensive control subjects form the epidemiologic F3 survey of the Kooperative Gesundheitsforschung in the region of Augsburg (KORA). About 408 patients with PA and 408 hypertensive controls were finally analyzed.
Results: The percentage of patients with a serum creatinine concentration above the normal range of 1.2 mg/dl was significantly higher in patients with PA than in hypertensive controls (129 of 408 (31.6%) vs 48 of 408 (11.8%), P<0.001). Accordingly, mean glomerular filtration rate (GFR) was significantly lower (P<0.001). Subgroup analysis showed that this was independent of sex, age or diabetes, but hypokalemic patients with PA had lower GFR than normokalemic patients. In a second step we analysed the long-term effect of specific treatment on renal function. Adrenalectomy for aldosterone producing adenoma reduced systolic blood pressure from a mean of 160 to 143.7 mmHg. In parallel, we observed an increase in serum creatinine and a decrease of GFR from 71.4 to 64 ml/min (P<0.001). A similar trend was seen with spironolactone treatment.
Conclusions: Glomerular filtration rate is reduced in patients with PA. Normalizing systemic blood pressure by removal of the adenoma reduces renal plasma flow. This uncovers the real extend of renal impairment in PA.