TF and Parkinson disease: A meta-analysis of all quantitative reports of iron in the substantia nigra and biofluids in Parkinson disease concluded that cerebrospinal iron levels were non-significantly higher and serum/plasma levels somewhat lower in parkinsonism, while CSF and serum/plasma ferritin and transferrin and serum/plasma lactoferrin and haptoglobin concentrations are similar in people with Parkinson disease and controls (reviewed: Jiménez-Jiménez et al. 2021).