Background: In primary aldosteronism (PA), aldosterone could affect glomerular hemodynamics by elevating renal vascular resistance and glomerular capillary pressure. However, the relationship between plasma aldosterone concentrations (PAC) and glomerular hemodynamics including efferent arteriolar resistance (Re), and afferent arteriolar resistance (Ra) in humans is still unclear. The aim of this study was to investigate the relationships of PAC with intraglomerular hemodynamic parameters in patients with PA.
Methods: An observational study of glomerular hemodynamics was performed using simultaneous measurements of plasma clearance of para-aminohippurate and inulin (Cin; glomerular filtration rate (GFR)) in 17 patients with PA. Kidney function was evaluated by Cin, estimated GFR based on serum creatine (eGFRcre) and serum cystatin C (eGFRcys) and creatine clearance (Ccr). Intraglomerular hemodynamic parameters, including Re, Ra, and intraglomerular hydrostatic pressure (Pglo) were calculated using Gomez's formulae.
Results: In the 17 PA cases, PAC was significantly correlated with Cin (rho = 0.752, P = 0.001) and eGFRcys (rho = 0.567, P = 0.018), but was not correlated with eGFRcre and Ccr. PAC was also significantly correlated with Pglo, Re, and urinary protein/day (rho = 0.775, P = 0.0004, rho = 0.625, P = 0.009, and rho = 0.625, P = 0.007, respectively). Multivariable regression analysis showed that PAC was significantly associated with Cin and Re. In comparing aldosterone-producing adenoma (APA) and non-APA cases, Cin was significantly elevated in APA (P = 0.037), whereas eGFRcre, eGFRcys, and Ccr were not. Re tended to be higher in APA (P = 0.064).
Conclusions: These results suggest high aldosterone causes glomerular hyperfiltration by constricting Re. Cin, but not eGFRcre and Ccr, may be useful for evaluating kidney function in PA.
Keywords: blood pressure; efferent arteriolar resistance; hypertension; inulin clearance; primary aldosteronism.
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