The A736V TMPRSS6 polymorphism influences hepcidin and iron metabolism in chronic hemodialysis patients: TMPRSS6 and hepcidin in hemodialysis.

BACKGROUND: Aim of this study was to evaluate whether the A736V TMPRSS6 polymorphism, a major genetic determinant of iron metabolism in healthy subjects, influences serum levels of hepcidin, the hormone regulating iron metabolism, and erythropoiesis in chronic hemodialysis (CHD). METHODS: To this end, we considered 199 CHD patients from Northern Italy (157 with hepcidin evaluation), and 188 healthy controls without iron deficiency, matched for age and gender. Genetic polymorphisms were evaluated by allele specific polymerase chain reaction assays, and hepcidin quantified by mass spectrometry. RESULTS: Serum hepcidin levels were not different between the whole CHD population and controls (median 7.1, interquartile range (IQR) 0.55-17.1 vs. 7.4, 4.5-17.9 nM, respectively), but were higher in the CHD subgroup after exclusion of subjects with relative iron deficiency (p = 0.04). In CHD patients, the A736V TMPRSS6 polymorphism influenced serum hepcidin levels in individuals positive for mutations in the HFE gene of hereditary hemochromatosis (p < 0.0001). In particular, the TMPRSS6 736 V variant was associated with higher hepcidin levels (p = 0.017). At multivariate analysis, HFE and A736V TMPRSS6 genotypes predicted serum hepcidin independently of ferritin and C reactive protein (p = 0.048). In patients without acute inflammation and overt iron deficiency (C reactive protein <1 mg/dl and ferritin >30 ng/ml; n = 86), hepcidin was associated with lower mean corpuscular volume (p = 0.002), suggesting that it contributed to iron-restricted erythropoiesis. In line with previous results, in patients without acute inflammation and severe iron deficiency the "high hepcidin" 736 V TMPRSS6 variant was associated with higher erythropoietin maintenance dose (p = 0.016), independently of subclinical inflammation (p = 0.02). CONCLUSIONS: The A736V TMPRSS6 genotype influences hepcidin levels, erythropoiesis, and anemia management in CHD patients. Evaluation of the effect of TMPRSS6 genotype on clinical outcomes in prospective studies in CHD may be useful to predict the outcomes of hepcidin manipulation, and to guide treatment personalization by optimizing anemia management.

Different cardiovascular responses to hemodialysis-induced fluid depletion and blood pressure compliance.

BACKGROUND: On the basis of cardiovascular compliance, hemodialysis (HD) patients can be classified as hypotension prone (HP) or hypotension resistant (HR). METHODS: We compare the hemodynamic behavior and myocardial performances in 6 HP and 6 HR patients before and after an isolated ultrafiltration (IU) session removing 3% of total body water. RESULTS: HP show higher basal plasma angiotensin II levels during IU (p<0.01), whereas angiotensin II remained unchanged in HR patients (p<0.001 between groups). The percentage changes of plasma volume (PV) was similar in the 2 groups. A significant reduction of cardiac index was observed only in the HP group (p<0.001 between groups). The mean values of heart rate remained significantly higher, whereas total peripheral resistances significantly fell in the HP in comparison with the HR group (p<0.001 between groups). During IU, the mean arterial pressure (MAP) changes were -10 +/- 3 mm Hg in the HP vs. -3.3 +/- 2 mm Hg in the HR group (p<0.001). Echocardiography data were collected before and after IU. All enrolled patients presented left ventricular hypertrophy; following IU, HP patients showed a reduction of mean left ventricular diameter (p<0.01), left atrial diameters and right atrial diameter, and a change in percentage of right atrium ejection fraction (p<0.001, p<0.01). CONCLUSIONS: In comparison with HR patients, HP patients before and after IU showed a defective arteriovenous tone adjustment to the PV changes, with a hemodynamic picture of abnormal sympathetic stimulation. Moreover, a reduced cardiac preload with both atrial and ventricular underfilling in these patients is at risk for a sudden drop in MAP.

HFE mutations modulate the effect of iron on serum hepcidin-25 in chronic hemodialysis patients.

BACKGROUND AND OBJECTIVES: Increased serum hepcidin has been reported in patients receiving chronic hemodialysis, and hypothesized to contribute to the alterations of iron metabolism of end-stage renal disease. However, no quantitative assessment is available to date; the clinical determinants are still under definition; and the role of genetic factors, namely HFE mutations, has not yet been evaluated. The aim of this study was to quantitatively assess serum hepcidin-25 in hemodialysis patients versus controls, and analyze the relationship between hepcidin, iron indices, HFE genotype, and erythropoietic parameters. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: Sixty-five hemodialysis patients and 57 healthy controls were considered. Hepcidin-25 was evaluated by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, HFE genotype by restriction analysis. RESULTS: Serum hepcidin-25 was higher in hemodialysis patients compared with controls. In patients, hepcidin-25 correlated positively with ferritin and C reactive protein, and negatively with serum iron after adjustment for confounders. Hepcidin/ferritin ratio was lower in patients with (n = 25) than in those without (n = 40) HFE mutations. At multivariate analysis, hepcidin-25 was independently associated with ferritin and HFE status. In a subgroup of 22 "stable" patients, i.e., with Hb levels on target, normal CRP levels, and absence of complications for at least 1 yr, hepcidin-25 was negatively correlated with Hb levels independently of confounders. CONCLUSIONS: Serum hepcidin-25 is increased in hemodialysis patients, regulated by iron stores and inflammation, and relatively reduced in subjects carrying frequent HFE mutations. Hepcidin-25 may contribute to the pathogenesis of anemia by decreasing iron availability.

HFE genotype influences erythropoiesis support requirement in hemodialysis patients: a prospective study.

BACKGROUND/AIMS: HFE protein controls iron absorption and cycling, and HFE mutations influence iron status. The aim was to evaluate the effect of the HFE genotype on the need for iron and erythropoietin in Italian hemodialysis patients. METHODS: Ninety-six prevalent patients were evaluated at the time of enrolment and prospectively followed for 3 years. Patients were given r-HuEPO and Fe3+-gluconate according to guidelines. The HFE genotype was determined by restriction analysis. RESULTS: Three patients (3%) carried the C282Y mutation, 4 (4%) were homozygous and 18 (19%) heterozygous for the H63D mutation, and 71 (74%) were negative for both. At enrolment, subjects positive for HFE mutations had higher iron stores (ferritin 617 +/- 663 vs. 423 +/- 386 ng/ml, p = 0.05), were receiving less iron (82.5 +/- 66 vs. 110 +/- 154 mg/month, p = 0.05) and a lower r-HuEPO dosage (98 +/- 83 vs. 142 +/- 138 U/kg/week, p = 0.03). Consistently during the study period, patients positive for HFE mutations received a lower amount of r-HuEPO (94.5 +/- 63 vs. 186 +/- 344 U/kg/week, p = 0.01) and iron (97 +/- 63 vs. 121 +/- 68 mg/month, p = 0.07). Upon Cox regression analysis, after adjustment for confounding variables, the presence of HFE mutations was associated with a reduced risk of death (HR 0.6, 95% CI 0.34-1.03, p = 0.06). CONCLUSION: HFE mutations reduce the amount of r-HuEPO and iron necessary to support erythropoiesis in hemodialysis.

Efficacy and safety of a very-low-protein diet when postponing dialysis in the elderly: a prospective randomized multicenter controlled study.

BACKGROUND: A supplemented very-low-protein diet (sVLPD) seems to be safe when postponing dialysis therapy. STUDY DESIGN: Prospective multicenter randomized controlled study designed to assess the noninferiority of diet versus dialysis in 1-year mortality assessed by using intention-to-treat and per-protocol analysis. SETTING & PARTICIPANTS: Italian uremic patients without diabetes older than 70 years with glomerular filtration rate of 5 to 7 mL/min (0.08 to 0.12 mL/s). INTERVENTION: Randomization to an sVLPD (diet group) or dialysis. The sVLPD is a vegan diet (35 kcal; proteins, 0.3 g/kg body weight daily) supplemented with keto-analogues, amino acids, and vitamins. Patients following an sVLPD started dialysis therapy in the case of malnutrition, intractable fluid overload, hyperkalemia, or appearance of uremic symptoms. OUTCOMES & MEASUREMENTS: Mortality, hospitalization, and metabolic markers. RESULTS: 56 patients were randomly assigned to each group, median follow-up was 26.5 months (interquartile range, 40), and patients in the diet group spent a median of 10.7 months (interquartile range, 11) following an sVLPD. Forty patients in the diet group started dialysis treatment because of either fluid overload or hyperkalemia. There were 31 deaths (55%) in the dialysis group and 28 deaths (50%) in the diet group. One-year observed survival rates at intention to treat were 83.7% (95% confidence interval [CI], 74.5 to 94.0) in the dialysis group versus 87.3% (95% CI, 78.9 to 96.5) in the diet group (log-rank test for noninferiority, P < 0.001; for superiority, P = 0.6): the difference in survival was -3.6% (95% CI, -17 to +10; P = 0.002). The hazard ratio for hospitalization was 1.50 for the dialysis group (95% CI, 1.11 to 2.01; P < 0.01). LIMITATIONS: The unblinded nature of the study, exclusion of patients with diabetes, and incomplete enrollment. CONCLUSION: An sVLPD was effective and safe when postponing dialysis treatment in elderly patients without diabetes.

HFE gene mutations and oxidative stress influence serum ferritin, associated with vascular damage, in hemodialysis patients.

BACKGROUND/AIMS: Hyperferritinemia has been associated with cardiovascular mortality in hemodialysis patients. The aim of this study was to evaluate whether serum ferritin was affected by iron and oxidative status and by genetic factors (HFE mutations and the Ala9Val MnSOD polymorphism), and to assess the association between ferritin and cardiovascular damage evaluated by ecocolor-Doppler. METHODS: 63 hemodialysis patients were tested for HFE and MnSOD genotype by restriction analysis and oxidative status; vascular damage was assessed by measuring intima-media thickness, and by detecting plaques at carotid and femoral arteries. RESULTS: Ferritin was correlated with transferrin saturation (p = 0.003), decreased iron-specific serum antioxidant activity (p = 0.01), age (p = 0.03), and C282Y and H63D HFE mutations (p = 0.05), but not with the MnSOD polymorphism. Ferritin was associated with advanced vascular damage, as evaluated by the presence of plaques, both at carotid (p = 0.03) and femoral arteries (p = 0.001), the other risk factors being age and low albumin. Low iron-specific antioxidant activity was associated with carotid plaques (p = 0.03). CONCLUSION: In hemodialysis patients, hyperferritinemia reflects a relative increase in iron availability and a decrease in iron-specific antioxidant activity, is favored by HFE mutations, and represents a risk factor for advanced cardiovascular damage.

Successful treatment of hemolytic uremic syndrome after liver-kidney transplantation.

INTRODUCTION: Hemolytic-uremic syndrome (HUS) is a rare complication in organ transplantation, characterized by hemolytic microangiopathic anemia, thrombocytopenia, and severe renal failure. The syndrome is a well-recognized complication in bone marrow transplantation, and has been likewise described in several cases of solid organs transplantation, but never in patients receiving combined liver and kidney transplantation. CASE REPORT: We describe a case of HUS in a 59-year-old woman who underwent combined liver-kidney transplantation for hepato-renal polycystic disease. Clinical and laboratory manifestations of the syndrome were severe and included renal failure, hemolytic anemia, severe thrombocytopenia, hypertension, and neurological damage. The initial treatment consisted of withdrawal of cyclosporine, introduction of low-dose tacrolimus, and administration of fresh frozen plasma (FFP) transfusion and heparin. Since there was no improvement in clinical or biochemical features, plasmapheresis with FFP replacement (2000 mL/day) followed by intravenous immunoglobulin (0.4 mg/Kg/day) was started. A rapid improvement in renal function, platelet count, and hemolytic anemia was observed. CONCLUSIONS: Based on the good response observed in our patient, we feel that an aggressive treatment with plasmapheresis and intravenous immunoglobulin should be offered to organ transplant recipients with severe HUS.

Changes in viremia and circulating interferon-alpha during hemodialysis in hepatitis C virus-positive patients: only coincidental phenomena?

BACKGROUND: It has been hypothesized that hemodialysis (HD) treatment per se can preserve patients from an aggressive course of hepatitis C virus (HCV) infection by reduction of viral load. The aim of the present study in HCV-positive (HCV+) HD patients is to determine whether HD induces the production of interferon-alpha (IFN-alpha) and if such production can contribute to viremia reduction. METHODS: To address this issue, HCV RNA and IFN-alpha levels were determined in 11 HCV+ patients immediately before and at the end of a 4-hour dialysis session using cellulosic membranes and 24 and 48 hours later, ie, immediately before the subsequent dialysis session using the same membrane and at the end of the dialysis session. The same protocol was repeated 1 week later using a high-biocompatibility synthetic membrane. RESULTS: HCV titer decreased in all patients after dialysis (range, 3% to 95%; P = 0.001) and thereafter progressively increased and returned to basal levels within 48 hours, with a new reduction during the next dialysis treatment. There was no significant difference in the magnitude of changes in HCV titers in tests performed using cellulosic or synthetic membranes. Plasma IFN-alpha levels increased markedly after dialysis using both cellulosic (in 9 of 11 cases) and synthetic membranes (in 10 of 11 cases; P < 0.01) and returned to basal levels within 48 hours; thereafter, IFN-alpha levels increased again during the next dialysis session. In some patients, plasma IFN-alpha levels after HD were approximately 50% of the level observed after therapeutic administration of 6 million units of IFN-alpha to 4 HD patients with chronic hepatitis. CONCLUSION: Although without a proven direct cause-effect relationship between HCV level reduction and induction of IFN-alpha after dialysis, our observation suggests an additional new mechanism for the unusually mild course of HCV infection in HD patients.

Pregnancy in lupus nephritis.

BACKGROUND: Fetal and maternal outcomes of 70 pregnancies in 48 women with lupus nephritis were retrospectively analyzed. METHODS: In 13 women, lupus nephritis developed during pregnancy (group A). In 38 patients with known lupus nephritis (including 3 patients in group A who had another pregnancy), 57 pregnancies occurred. In 6 patients, a therapeutic abortion was performed. The remaining 51 pregnancies were considered pregnancies in lupus nephritis (group B). RESULTS: Fetal loss was 36% (38%, group A; 35%, group B); it decreased from 46% in the 1970s to 30% in the last decade. Among 41 live births, there were 13 preterm deliveries and 28 full-term deliveries. At multivariate analysis, proteinuria (P = 0.025), arterial hypertension (P = 0.05), and antiphospholipid antibodies (P = 0.01) were independent predictors of fetal loss. In group A, 3 patients developed acute renal failure, irreversible in 1 patient (7.7%); all other patients recovered after steroid and immunosuppressive therapy. In group B, 12 renal flares and 1 extrarenal flare developed during pregnancy or the postpartum period. Two patients progressed to irreversible renal failure (3.9%), and 1 of the 2 patients died. All other patients recovered. The incidence of renal flares before or during pregnancy was not different (P = 0.51). Renal quiescence at the onset of pregnancy was the only predictor of favorable maternal outcome. CONCLUSION: Proteinuria, hypertension, and positivity of antiphospholipid antibodies are independent predictors of adverse fetal outcome. Quiescence of renal disease is the only predictor of favorable maternal outcome.

Calcium and phosphate plasma levels in dialysis patients after dietary Ca-P overload. Role of gastric acid secretion.

In normal subjects, the gastric ionisation of calcium and phosphate seems to be a prerequisite for their intestinal absorption. We investigated the behavior of the plasma calcium and phosphate profile in 30 patients on regular dialysis treatment in the 6 h following a meal containing 1 g of calcium and 2 g of phosphate. Moreover, to assess the role of gastric acidity, the study was repeated after 3 days on omeprazole administration, to nearly abolish gastric acid secretion. Both total plasma calcium and ionized calcium peaked after the meal (at 30 and 120 min, respectively) only in basal study, while no peak was observed after the administration of omeprazole. Surprisingly, both in basal and in the omeprazole study the levels of plasma phosphate did not increase after the test meal. In conclusion, as in normal subjects, the gastric ionization of dietary calcium promotes the intestinal absorption of calcium in uremic patients on dialysis treatment, while the acute gastric acid inhibition by omeprazole reduced the intestinal calcium transport. In contrast, with the "trade off" hypothesis we did not observe any postprandial phosphate peak after the dietary load, and, in contrast with normal subjects, omeprazole administration did not influence the phosphate profile.