Serum hepcidin-25 may replace the ferritin index in the Thomas plot in assessing iron status in anemic patients

INTRODUCTION

Biochemical markers of iron deficiency do not distinguish iron-deficient anemia (IDA) from the anemia of chronic disease (ACD) and the combined state of ACD/IDA. Serum hepcidin-25 might be a marker resolving this problem. We investigated the extent to which serum hepcidin-25 enables the differentiation of the states above in comparison with the ferritin index plot, the so-called Thomas plot [soluble transferrin receptor (sTfR)/log ferritin and the reticulocyte hemoglobin content (CHr)].

METHODS

Serum hepcidin-25 was determined in 155 anemic patients who were classified as having latent iron deficiency (latent ID), IDA, ACD, or ACD/IDA using the ferritin index plot (Thomas plot). Hepcidin-25 was determined using an isotope-dilution micro-HPLC-tandem mass spectrometry method. The ability to discriminate among these states based on serum hepcidin-25 alone or in combination with the CHr was evaluated in a receiver operating characteristic curve analysis and a comparison with the recently established ferritin index plot.

RESULTS

Serum hepcidin-25 correlated with ferritin and the ferritin index. Use of a hepcidin-25 cutoff level of ≤4 nmol/l allowed the differentiation of IDA from ACD and ACD/IDA. Furthermore, the discrimination of ACD/IDA from ACD required combination with CHr in a new plot (hepcidin-25 and the CHr). The hepcidin-25 plot and the ferritin index plot showed a good correspondence in the differentiation of iron states in patients with anemia.

CONCLUSION

Patients with IDA can be differentiated from ACD and ACD/IDA but not ACD from ACD/IDA based on hepcidin-25 alone. The combination of hepcidin-25 with CHr in the hepcidin-25 plot was useful for the differentiation of the states above.

Serum hepcidin concentration in chronic haemodialysis patients: associations and effects of dialysis, iron and erythropoietin therapy

BACKGROUND

Hepcidin, a liver-derived peptide induced by iron overload and inflammation, is a major regulator of iron homeostasis. As hepcidin decreases gastrointestinal iron absorption and recirculation from monocytes, over-expression is associated with the development of anaemia.

METHODS

We studied the associations between circulating hepcidin levels and various laboratory parameters related to anaemia and/or inflammation in 20 patients on chronic haemodialysis. Furthermore, we determined the impact of dialysis and iron and/or erythropoietin (rhEpo) supplementation therapy on hepcidin serum concentrations. The patients were withheld from iron and rhEpo for 2 weeks before study entry. Hepcidin was measured by liquid chromatography-mass spectrometry (LC-MS/MS); serum iron and haematological parameters, cytokines and pro-hepcidin by commercially available enzyme-linked immunosorbent assays (ELISA) or standard automated methods.

RESULTS

While hepcidin levels at baseline were not correlated to pro-hepcidin, interleukin-6 or transforming growth factor-beta concentrations, we found significant associations with reticulocyte count (r = -0.55; P = 0.015), serum iron (r = 0.7; P = 0.004) and ferritin levels (r = 0.63; P = 0.004) and transferrin saturation (r = 0.69, P = 0.001). Dialysis using either a high or a low flux biocompatible dialyser resulted in a significant decrease of hepcidin concentrations, which returned to pre-dialysis values before the next dialysis session. When studying the effects of anaemia treatment, we observed a significant reduction of hepcidin levels following administration of rhEpo but not iron.

CONCLUSIONS

Hepcidin levels in stable haemodialysis patients appear to reflect systemic iron load, but not inflammation. Due to the negative association between reticulocyte counts and hepcidin, the reduction of circulating hepcidin concentrations by dialysis and/or rhEpo treatment may positively affect erythropoiesis.

Miniaturized monolithic disks for immunoadsorption of cardiac biomarkers from serum

Immunoadsorbers based on 2.0 x 6.0 mm i.d., epoxy-bearing, methacrylate-based monolithic disks were developed in order to target myoglobin and N-terminal pro-natriuretic peptide (NT-proBNP), two biomarkers involved in cardiovascular disease. In both cases, antibodies were successfully coupled to the polymeric disk material. The developed immunoadsorbers permitted the selective isolation of myoglobin and NT-proBNP from human serum. Myoglobin was successfully isolated and detected from serum samples at concentrations down to 250 fmol microL(-1). However, the affinity of the antibodies was not sufficient for the analysis of low-concentration clinical samples. Frontal analysis of anti-NT-proBNP disks revealed the ability of the immunoadsorber to bind up to 250 pmol NT-proBNP, which is more than sufficient for the analysis of clinical samples. Anti-NT-proBNP disks showed good stability over more than 18 months and excellent batch-to-batch reproducibility. Moreover, anti-NT-proBNP disks permitted the isolation of NT-proBNP at concentrations down to 750 amol microL(-1) in serum, corresponding to concentrations of strongly diseased patients. Using reversed-phase trapping columns, the detection of NT-proBNP eluted from immunoadsorbers by mass spectrometry was achieved for concentrations down to 7.8 fmol microL(-1).

Preparation of a candidate primary reference material for the international standardisation of HbA1c determinations

We prepared a candidate primary reference material for the forthcoming international standardisation of beta-N-terminal glycated hemoglobin A measurements. It consists of well-defined mixtures of purified beta-N-terminal glycated hemoglobin A and non-glycated hemoglobin A. First, beta-N-terminal glycated hemoglobin A and non-glycated hemoglobin A were isolated, purified to homogeneity, and characterised. The techniques used were cation exchange and affinity chromatography for the purification, and high performance liquid chromatography, capillary isoelectric focusing, electrospray ionisation mass spectrometry, and peptide mapping for the characterisation. Hemoglobins from blood of healthy, non-diabetic volunteers were obtained with a purity of > 99.5% for non-glycated hemoglobin A and of > 98.5% for beta-N-terminal glycated hemoglobin A. However, results from peptide mapping indicate that the beta-N-terminal glycated hemoglobin A preparations still contain some non-beta-N-terminal glycated hemoglobins, co-eluting with beta-N-terminal glycated hemoglobin A. The exact content of beta-N-terminal glycated hemoglobin A in these preparations could be determined by a procedure consisting of standard addition, enzymatic cleavage and quantification of the resulting beta-N-terminal peptides to be in the range from 95-97.5%. Since the beta-N-terminal glycated hemoglobin A and non-glycated hemoglobin A content could be exactly determined in the materials prepared, mixtures of both components could be successfully used to calibrate the candidate reference methods.

Candidate reference methods for hemoglobin A1c based on peptide mapping

A reference method that specifically measures hemoglobin (Hb) A1c is an essential part of the reference system for the international standardization of Hb A1c/glycohemoglobin. We have developed a new method for quantification, based on the specific N-terminal residue of the hemoglobin beta-chains. Enzymatic cleavage of the intact hemoglobin molecule with endoproteinase Glu-C has been optimized to obtain the beta-N-terminal hexapeptides of Hb A1c and Hb A0. These peptides have been separated by reversed-phase HPLC and quantitated by electrospray ionization-mass spectrometry (method A) or by capillary electrophoresis (method B). With these peptides and hyphenated separation techniques, it has been possible to overcome the insufficient resolution of currently used protein separation systems for Hb A1c.

Multidimensional high-performance liquid chromatography on Pinkerton ISRP and RP18 columns: direct serum injection to quantify creatinine

A two-dimensional high-performance liquid chromatographic method for the determination of creatinine with direct serum injection without sample pretreatment has been developed. The column-switching technique allowed a switch from columns packed with internal surface reversed-phase (ISRP) material to columns of almost any other material, even if the eluents necessary in a particular case do not appear to be directly compatible. A Pinkerton ISRP column, which stands out because of its very good stability when loaded with undiluted serum samples, was used as precolumn. The creatinine-containing fraction was switched to a reversed-phase Shandon RP18 column and was focused there by alteration of the eluent from pH 6.5 to phosphoric acid-ion-pair reagent. The separation occurs via a pH gradient, with ultraviolet detection at 234 nm. This method stands out particularly for its good long-term stability, simple sample handling without pretreatment, high selectivity, a broad linearity (0.3-30 mg/dl creatinine), good reproducibility (inter-assay coefficient of variation less than 3%) and high recovery (97-100%) relative to values obtained with gas chromatography-mass spectrometry.

Chemical Varieties of Essential Oils from Elsholtzia polystachya from Two Different Locations in India1

Capillary GC, GC-MS, IR, GC-IR, (1)H- and (13)C-NMR studies of the essential oil from the leaves and cones of ELSHOLTZIA POLYSTACHYA collected from two different locations in India revealed that one oil contained 1,8-cineol (37.3%), the other one perillene (61.2%) as the main constituent.

Terpenoids from Elsholtzia Species; II1. Constituents of Essential Oil from a New Chemotype of Elsholtzia cristata

Capillary GC, GC-MS, (1)H-, and (13)C-NMR spectroscopy revealed that the essential oil of ELSHOLTZIA CRISTATA Willd. growing in the Kumaun region contains 88% dehydroelsholtzia ketone along with some minor acylfuran derivatives. This species with respect to its oil composition is unlike that which grows in Japan and Kashmir, and contains elsholtzia ketone as the main constituent.

Constituents of Essential Oil of Elsholtzia strobilifera1

The composition of the essential oil of ELSHOLTZIA STROBILIFERA, growing around Naini Tal (India) has been investigated by capillary gas-chromatography, gas-chromatography-mass spectrometry and (13)C-NMR spectroscopy. Out of about 50 identified mono- and sesquiterpenoids, pinocarvone is the most abundant component, which has not been identified in any species of ELSHOLTZIA before. The acylfuran derivatives reported from other species of ELSHOLTZIA could not be detected.