Mass spectrometry-based hepcidin measurements in serum and urine: analytical aspects and clinical implications.

Contains fulltext : 52294.pdf (publisher's version ) (Open Access)BACKGROUND: Discovery of the central role of hepcidin in body iron regulation has shed new light on the pathophysiology of iron disorders. Information is lacking on newer analytical approaches to measure hepcidin in serum and urine. Recent reports on the measurement of urine and serum hepcidin by surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) necessitate analytical and clinical evaluation of MS-based methodologies. METHODS: We used SELDI-TOF MS, immunocapture, and tandem MS to identify and characterize hepcidin in serum and urine. In addition to diagnostic application, we investigated analytical reproducibility and biological and preanalytical variation for both serum and urine on Normal Phase 20 and Immobilized Metal Affinity Capture 30 ProteinChip arrays. We obtained samples from healthy controls and patients with documented iron-deficiency anemia, inflammation-induced anemia, thalassemia major, and hereditary hemochromatosis. RESULTS: Proteomic techniques showed that hepcidin-20, -22, and -25 isoforms are present in urine. Hepcidin-25 in serum had the same amino acid sequence as hepcidin-25 in urine, whereas hepcidin-22 was not detected in serum. The interarray CV was 15% to 27%, and interspot CV was 11% to 13%. Preliminary studies showed that hepcidin-25 differentiated disorders of iron metabolism. Urine hepcidin is more affected by multiple freeze-thaw cycles and storage conditions, but less influenced by diurnal variation, than is serum hepcidin. CONCLUSION: SELDI-TOF MS can be used to measure hepcidin in both serum and urine, but serum requires a standardized sampling protocol

Identification of a novel panel of cerebrospinal fluid biomarkers for Alzheimer's disease

An early and accurate diagnosis of Alzheimer's disease (AD) is required to initiate symptomatic treatment with currently approved drugs and will be of even greater importance if disease modifying compounds in development display a clinical effect. Protein profiles of human cerebrospinal fluid samples from AD patients (n = 95) and population-based healthy controls (n = 72) were analyzed by SELDI-TOF-MS in order to discover and characterize novel candidate biomarker combinations that differentiate AD patients from normal aging in this explorative study. Thirty candidate biomarkers (ROC AUC > 0.7) were discovered that could differentiate patients with AD from healthy controls. Protein sequence determination and positive identification of 15 biomarkers revealed potential associations between the identified markers and AD pathogenesis. A multi-marker combination of five peaks could distinguish AD from healthy control individuals with high sensitivity (97%) and specificity (98%). The panel of five markers was tested on a blinded independent data set of 30 AD samples and 28 controls giving 100% sensitivity and 97% specificity. This novel panel of biomarkers could potentially be used to improve the accuracy of diagnosis of AD