Lower hemoglobin levels in patients with parkinson's disease are associated with disease severity and iron metabolism

Although several lines of evidence suggest that low levels of hemoglobin are a risk factor for Parkinson's disease (PD), few studies have examined changes in hemoglobin after PD onset. In this study, we quantify alterations in hemoglobin after the onset of PD and explore possible mechanisms for changes in hemoglobin. We enrolled 213 PD and 219 control subjects between 2013 and 2014 at the Third Affiliated Hospital of Sun Yat-sen University and Nanfang Hospital of Southern Medical University. We collected data from routine blood tests (including markers of iron metabolism) and measured basic clinical parameters. The hemoglobin levels were lower in PD patients relative to control subjects (125.1±15.68 g/L and 139.9±11.83 g/L, respectively; p＜0.001). Serum iron levels did not change in PD patients compared to control subjects (14.92±4.88 μmol/L and 15.73±4.40 μmol/L, respectively; p=0.35). Total iron binding capacity (TIBC) was also unaltered (PD group: 48.29±9.13 μmol/L; control group: 49.74±8.35 μmol/L; p=0.43). The level of ferritin in PD and control subjects was 174.07±74.04 ng/mL and 191.82±91.49 ng/mL (p=0.04), respectively. We further analyzed the relationship between iron metabolism and PD by stratifying the data by disease severity and found that late-stage PD patients have lower levels of iron, ferritin, and TIBC (14.36±4.95 μmol/L, 162.24±71.25 μmol/L and 46.84±10.15 ng/mL) compared to age-matched controls. Significant correlations were observed between hemoglobin levels and iron metablism. Our results suggest that hemoglobin levels are lower in PD patients compared to controls and are associated with the severity of PD and iron metabolism.