To date, concentrations of the promising biomarker hepcidin have only been assessed in serum of relatively small series of healthy volunteers and patients. We assessed age-and sex-stratified reference ranges of serum hepcidin concentration in a selected reference set and performed regression analyses to study associations between hepcidin and (biochemical) variables in a large, wellphenotyped sample of the general population (n ‫؍‬ 2998). All participants filled out a questionnaire on lifestyle, health status, and medical history. Serum measurements of iron parameters, liver enzyme alanine aminotransferase, creatinine and C-reactive protein were available. Serum hepcidin concentrations were lower for premenopausal than for postmenopausal women (median, 4.1nM vs 8.5nM, respectively). Hepcidin concentrations in men were constant over age (median, 7.8nM).

BACKGROUND:The peptide hormone hepcidin plays a central role in regulating dietary iron absorption and body iron distribution. Many human diseases are associated with alterations in hepcidin concentrations. The measurement of hepcidin in biological fluids is therefore a promising tool in the diagnosis and management of medical conditions in which iron metabolism is affected.CONTENT: We describe hepcidin structure, kinetics, function, and regulation. We moreover explore the therapeutic potential for modulating hepcidin expression and the diagnostic potential for hepcidin measurements in clinical practice.

Assays for the detection of the iron regulatory hormone hepcidin in plasma or urine have not yet been widely available, whereas quantitative comparisons between hepcidin levels in these different matrices were thus far even impossible due to technical restrictions. To circumvent these limitations, we here describe several advances in time-of flight mass spectrometry (TOF MS), the most important of which concerned spiking of a synthetic hepcidin analogue as internal standard into serum and urine samples. This serves both as a control for experimental variation, such as recovery and matrix-dependent ionization and ion suppression, and at the same time allows value assignment to the measured hepcidin peak intensities. The assay improvements were clinically evaluated using samples from various patients groups and its relevance was further underscored by the significant correlation of serum hepcidin levels with serum iron indices in healthy individuals. Most importantly, this approach allowed kinetic studies as illustrated by the paired analyses of serum and urine samples, showing that more than 97% of the freely filtered serum hepcidin can be reabsorbed in the kidney. Thus, the here reported advances in TOF MS-based hepcidin measurements represent critical steps in the accurate quantification of hepcidin in various body fluids and pave the way for clinical studies on the kinetic behavior of hepcidin in both healthy and diseased states.

BACKGROUND:Hepcidin is an iron-regulatory peptide hormone that consists of 3 isoforms: bioactive hepcidin-25, and inactive hepcidin-22 and hepcidin-20. Hepcidin is instrumental in the diagnosis and monitoring of iron metabolism disorders, but reliable methods for its quantification in serum are sparse, as is knowledge of their relative analytical strengths and clinical utility.

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We conclude that hepcidin levels were suppressed during the second and third trimester of pregnancy, which was likely determined by the occurrence of iron deficiency. These data give insight in iron homeostasis during normal pregnancy.

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Measurements of the iron regulatory hormone hepcidin by various methodologies and laboratories are not harmonized. As a result different numeric results are obtained for the same clinical sample. We investigated whether better agreement between plasma hepcidin methods can be achieved by harmonization. Native plasma pools (n 5 11) of a variety of hepcidin concentrations and blank plasma spiked with three different quantities of synthetic hepcidin-25 purchased from two different commercial sources (n 5 6), were distributed in duplicate among 21 methods worldwide. We assessed commutability by comparing results from synthetic hepcidin with those from native samples in various method couples by Bland-Altman plots. Methods differed substantially in absolute values and reproducibility. For the majority of methods we found that samples with synthetic hepcidin-25 were noncommutable with the native samples. In an attempt to harmonize by using native hepcidin results, we selected two methods that showed good mutual agreement of native results and calculated consensus values as the medians for the 11 duplicate native samples obtained by these two methods. Finally, we constructed algorithms enabling the laboratories to calculate the hepcidin consensus (HEPCON) value using their own native hepcidin results. We found that the use of these algorithms substantially reduced the between-method CV. Until commutable materials are defined, hepcidin harmonization can be achieved by exploiting specific algorithms, allowing each lab to report their native hepcidin concentrations in HEPCON values. This study represents the first step toward harmonization of plasma hepcidin methods and facilitates aggregation of hepcidin data from different research investigations. Am. J. Hematol. 87:977-983, 2012. V