Glomerular Hyperfiltration: An Early Marker of Nephropathy in Fabry Disease

Background and objectives: Progressive nephropathy is one of the main features of Fabry disease (FD). It has been supposed that an early phase, clinically silent disease occurs in childhood and adolescence and is characterized by glomerular hyperfiltration (HF). Surprisingly, although HF has been reported in several studies, its prevalence is at present unknown. The focus of our study was to determine the prevalence of HF in a cohort of patients with FD and to identify the factors associated with a high risk of HF. Methods: To address this issue, a retrospective observational study of 87 patients with genetically confirmed FD was performed. HF was defined as an estimated glomerular filtration rate (eGFR) > 130 mL/min/1.73 m corrected for age (> 40 years:-1 mL/min/1.73 m /year). Results: HF occurred in 21 patients (24% of our population), and increased to 50% when only young adults were considered. Hyperfiltrating patients were younger and had lower proteinuria levels than those without HF. The prevalence of cardiovascular and other manifestations of FD was significantly lower in hyperfiltering patients. Conclusions: Our study showed a negative correlation between eGFR and age, and with proteinuria levels and the presence of cardiovascular and other manifestations of FD. These data favor the view that HF in Fabry patients could be related predominantly to a predisease state. Even in the absence of a "measured" GFR, HF should be regarded as an early marker of Fabry nephropathy, and its recognition and confirmation by true GFR seems a relevant feature to address the issue of the potential benefit of nephroprotective treatments at the early stage of Fabry nephropathy.