Parkinson?s disease (PD) is the second most common neurodegenerative condition characterized
by motor and non-motor symptoms causing a great burden in patients? quality of life.
PD has been associated with various metabolic factors such as diabetes, hypertension,
and more recently chronic kidney disease where proteinuria has been associated with
an increased risk. The presence of small amounts of albumin in urine, microalbuminuria,
is a common biomarker for endothelial damage and a predictive factor for not only
cardiovascular but also neurological dysfunction. Multiple studies have assessed potential
biomarkers for PD progression with great heterogeneity, we hypothesize the use of
microalbuminuria as a potential marker that correlates with PD severity and might
represent a feasible and simple method of evaluating PD patients in clinical practice.
Evidence supporting the present hypothesis comes from oxidative stress, insulin resistance,
and endothelial dysfunction. Oxidative stress is a key element in PD pathogenesis;
studies have shown lower antioxidant capacity as PD progresses. On the other side,
insulin signaling plays an important role in neuronal growth and survival, with its
resistance being associated with PD. Microalbuminuria has been associated with both
processes; increased levels of oxidative stress markers and decreased insulin sensitivity,
hence its screening in PD might reflect these common pathological mechanisms. Moreover,
the low vitamin D levels observed in PD patients, which are correlated with endothelial
dysfunction and disease severity, might contribute to microalbuminuria induction.
More evidence on this vascular approach comes from white matter lesions (WML), observed
in brain imaging, which have been significantly associated with motor and non-motor
function in PD patients and are independently associated with microalbuminuria. In
this manner, an oxidant and insulin resistant environment, along with low vitamin
D levels in PD patients, which are associated with microalbuminuria, might contribute
altogether to WML. As the latter are correlated with motor and non-motor function,
microalbuminuria might thus give insight on PD status. Prospective cohort studies
with an adequate sample size, follow-up, and a thorough battery of clinical tests
for PD are needed to confirm this hypothesis.