Untreated Hereditary Hemochromatosis Research Articles

Striking Difference in Iron Utilization between Oral and Intravenous Iron in Various Anemias and Hemochromatosis

Introduction Patients with hereditary hemochromatosis (HH) and non-transfusion-dependent hereditary anemia (HA NTD) both express low hepcidin levels, leading to increased intestinal iron absorption and, ultimately, predominantly parenchymal iron overload. Knowledge about iron absorption in humans stems from iron absorption or utilization studies with radio-labeled iron performed in the 60-70s from the last century. Here, we present unique data of combined absorption and utilization studies in a large cohort of patients with primary and secondary hemochromatosis.Methods We retrospectively analyzed the data from iron absorption and kinetics studies performed from 1972 until 1994 as part of routine clinical practice in patients with iron-related health problems at the University Medical Center Utrecht, the Netherlands. A radioactive tracer dose of oral (1 mg) 59Fe with 51Cr as non-absorbable indicator, or intravenous (10 µCi) 59Fe was administered. Radio-activity was measured with a whole-body counter to assess absorption and with a gamma-counter to determine radio-activity in peripheral blood samples to calculate the amount of iron utilized for red blood cell (RBC) production.Main findings Iron absorption was analyzed in 6 distinct groups with and without iron overload and iron reducing therapy (table). Iron uptake is the percentage of the iron test dose taken up by enterocytes, retention the percentage retained in the body 14 days after ingestion, and transfer the fraction of iron taken up that is retained in the body. Iron uptake, transfer and retention were significantly higher in patients with treated and untreated HH and iron deficiency (ID) compared with healthy controls (p<0.01). Notably, uptake, transfer and retention were also significantly higher in the analyses of patients with treated or untreated HA NTD (including 19 congenital sideroblastic anemia, 6 hereditary spherocytosis, 5 congenital dyserythropoietic anemia, 3 non-transfusion dependent thalassemia, 4 Hb Adana, 2 hexokinase deficiency and 1 PKD) than in analyses of healthy controls (p<0.01). Next, iron retention was used to calculate the percentage of iron utilized for RBC production after 14 days. Mean percentages of RBC iron utilization (RBCIU) after an oral iron test dose were 37% (SD 17%) in untreated HA NTD, 53% (SD 19%) in treated HA NTD, 55% (SD 20%) in untreated HH, 70% (SD 22%) in treated HH, and 99% (SD 22%) in ID patients. Surprisingly, RBCIU was lower after oral than after intravenous iron in patients with HA NTD or HH (figure 1). The difference between oral and intravenous RBCIU was expressed as percentage of intravenous RBCIU, and denominated as the LIR (liver iron retention). The LIR had a mean value of 28% (SD 26%) in untreated HH, 23% (SD 24%) in untreated HA NTD, and 16% (SD 25%) in treated HH patients, all significantly higher than the LIR of 1% (SD 22%) measured in ID patients (p<0.05). The LIR was strongly correlated to iron saturation (r=0.41; p<0.01).Main conclusions Of major interest is the observation that a substantial fraction of oral iron retained in patients with iron overload was not utilized for erythropoiesis. Under circumstances of high transferrin saturation, a part of iron transported from enterocytes into the portal circulation will be non-transferrin-bound iron (NTBI). A part of this NTBI will be available as labile plasma iron (LPI), a form of iron with high redox potential, and the capacity to rapidly cross membranes via transporters and channels. Recently it was shown that in iron-overloaded conditions LPI is almost completely taken up after passage of the liver and this is facilitated by ZIP14 in a non-transferrin-dependent way. (Jenkitkasemwong et al. Cell Metabolism, 2015: 22(1), 138-150). We therefore hypothesize that LPI produced primarily in the portal system (oral dosed iron) is primarily taken up in the liver and that LPI produced elsewhere in the circulation (intravenous dosed iron) may be taken up by other organs as well.In conclusion, our data is suggestive of the existence of significant hepatic scavenging of NTBI/LPI under iron-overloaded conditions. This could explain the distinct patterns of transfusion-dependent and transfusion-independent iron overload and we suggest that ZIP14 could facilitate this. [Display omitted] Disclosuresvan Wijk:Agios Pharmaceuticals: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; RR Mechatronics: Research Funding. van Beers:RR Mechatronics: Research Funding; Bayer: Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Blood removal therapy in hereditary hemochromatosis induces a stress response resulting in improved genome integrity.

Hereditary hemochromatosis (HH) is a common disease of iron metabolism, manifesting with iron overload and affecting up to 1% of individuals of northern European descent. Untreated HH can result in irreversible damage of the liver and pancreas, potentially leading to cancer and diabetes. Therapy consists of normalizing iron stores by repeated blood donations (phlebotomy). Treated HH patients have normal survival rates and report less tiredness after phlebotomy; however, it is not understood why musculoskeletal symptoms may persist in spite of iron removal. We hypothesize that phlebotomy therapy does not simply reverse iron accumulation but has additional effects at the subcellular level. In particular, the systemic impact of phlebotomy on mitochondria and genome integrity is largely unknown. The effects of phlebotomy therapy on mitochondrial iron proteins and genome integrity were investigated in peripheral blood mononuclear blood cells from HH patients. After the reduction of systemic iron load in these patients with phlebotomy, we observed increased expression of mitochondrial superoxide dismutase, reduced iron sulfur assembly protein (Iscu1/2), and improved genome integrity. We conclude that phlebotomy therapy in HH does not merely restore systemic iron homeostasis, but induces an "oxidative stress" defense response that manifests as improved genome integrity. These findings provide novel insights into an ancient therapy.

Second international round robin for the quantification of serum non-transferrin-bound iron and labile plasma iron in patients with iron-overload disorders.

Non-transferrin-bound iron and its labile (redox active) plasma iron component are thought to be potentially toxic forms of iron originally identified in the serum of patients with iron overload. We compared ten worldwide leading assays (6 for non-transferrin-bound iron and 4 for labile plasma iron) as part of an international inter-laboratory study. Serum samples from 60 patients with four different iron-overload disorders in various treatment phases were coded and sent in duplicate for analysis to five different laboratories worldwide. Some laboratories provided multiple assays. Overall, highest assay levels were observed for patients with untreated hereditary hemochromatosis and β-thalassemia intermedia, patients with transfusion-dependent myelodysplastic syndromes and patients with transfusion-dependent and chelated β-thalassemia major. Absolute levels differed considerably between assays and were lower for labile plasma iron than for non-transferrin-bound iron. Four assays also reported negative values. Assays were reproducible with high between-sample and low within-sample variation. Assays correlated and correlations were highest within the group of non-transferrin-bound iron assays and within that of labile plasma iron assays. Increased transferrin saturation, but not ferritin, was a good indicator of the presence of forms of circulating non-transferrin-bound iron. The possibility of using non-transferrin-bound iron and labile plasma iron measures as clinical indicators of overt iron overload and/or of treatment efficacy would largely depend on the rigorous validation and standardization of assays.

Hereditary hemochromatosis: a neglected diagnosis in orthopedics

Hereditary hemochromatosis (HH) is a not uncommon autosomal recessive and potentially life-threatening disease. The hemochromatosis gene was identified by Feder et al. in 1996. About 1 in 200 individuals is estimated to be homozygous for the most common mutation—C282Y/C282Y. In the classical form of the disease, cysteine is substituted by tyrosine at amino acid 282 in both alleles. The so-called compound heterozygoty is less common (representing about 10% of cases) but is also compatible with HH. Here, histidine is substituted by aspartic acid at amino acid 63 in one allele and cysteine by tyrosine at amino acid 282 in the other (C282Y/H63D). Due to increased intestinal absorption, homozygotes develop iron overload but penetrance is very variable (McCune et al. 2006). Most orthopedic surgeons meet patients with undiagnosed HH on a yearly basis and an early diagnosis and treatment is important in order to avoid cirrhosis of the liver. Also, the risk of developing hepataocellular cancer is at least 20-fold higher than in their first-degree relatives (Elmberg et al. 2003). Fatigue and arthritis, unspecific and therefore often neglected, are common presentations whereas the classic bronze diabetes (darkened skin, diabetes, and cirrhosis) is the final stage of untreated HH that is very rarely seen (McDonell et al. 1999). A survey of 2,851 patients with hemochromatosis showed that patients had consulted a physician after an average of 2 years of symptoms, and on average it took a further 10 years before the diagnosis was made (McDonell et al. 1999). This is unfortunate, since medical treatment—i.e. regular phlebotomy—is effective. During the period 2001–2008, I replaced 93 ankles in 86 patients and 4 of these patients proved to have hemochromatosis. Here I have reviewed the orthopedic manifestations in 7 patients who had one or both ankles replaced during this period, 3 of whom had had their ankles replaced elsewhere. Cases The original records from all orthopedics departments and units of gastroenterology involved were consulted and the author interviewed the patients at least twice. All but 1 patient were below the age of 45 when they had their first joint symptoms, and there was usually a long patient’s and doctor’s delay before diagnosis and treatment. In 4 cases the hip, knee or ankle joint, and not the MP joints, was the first joint to become symptomatic. Only in one case (patient 5) did the joint symptoms start after the time that the diagnosis of HH had been made (Table 1). Table 1. Demographic data, laboratory findings, and joints replaced in 7 patients with hereditary hemochromatosis

Family‐based Detection for Hereditary Hemochromatosis

The purpose of this study was to examine motivators for and barriers to family-based detection for hereditary hemochromatosis (HH). HH patients (n = 60) and HH siblings (n = 25) participated in one-on-one or group interviews. Patients and siblings understood that HH "runs in families," but not that siblings are at higher HH risk than other family members. Patient motivators included concern for siblings' health, seriousness of untreated HH, and doctor's encouragement to tell siblings that they need to seek diagnostic testing. Siblings were motivated by the seriousness of HH. Barriers included lack of symptoms, belief that HH was rare, and assumption that their doctor would have mentioned the risk of HH. Family-based detection continues to be a feasible part of an overall public health strategy to promote early detection of HH. Greater awareness of HH and its potential consequences, especially among high-risk groups, provides an additional potential avenue for public health action.

Association between increased iron stores and impaired endothelial function in patients with hereditary hemochromatosis

ObjectivesWe studied associations between iron status and early functional and structural vascular abnormalities in patients with hereditary hemochromatosis (HH). BackgroundIron may be involved in atherogenesis, and patients bearing a genetic mutation associated with HH are possibly at risk of developing coronary heart disease. MethodsWe studied the vascular properties of 41 HH patients who had homozygosity for the C282Y mutation, along with 51 age-matched control subjects, by determination of endothelium-dependent dilation (EDD) of the brachial artery and intima-media thickness (IMT) of the carotid artery. ResultsMale HH patients who were not receiving phlebotomy therapy showed a reduced EDD and increased IMT compared with controls and HH patients receiving therapy. In female HH patients, irrespective of treatment status, vascular parameters were not different from those of controls, and none of these patients had severe iron overload. In HH patients, increased iron load was significantly associated with reduced EDD and increased IMT. Moreover, we found a positive correlation between body iron stores and indicators of oxidative stress. When previously untreated male HH patients were re-investigated after intensive phlebotomy therapy, a significant improvement in EDD was observed (2.6 ± 1.3% before vs. 5.5 ± 2.1% after treatment, p = 0.0015). ConclusionsImpaired endothelial function and increased IMT are associated with iron overload, with subsequent induction of oxidative stress, and are not linked to a genetic disability in HH patients. Consequent iron-depletion therapy normalizes endothelial function and may thus reduce the increased risk of cardiovascular events. Female patients may be at a reduced risk, presumably due to continuous iron loss by menstruation.

Mutations of the HFE Gene and the Risk of Hepatocellular Carcinoma

ABSTRACT: The discovery of the C282Y and H63D point mutations in the hereditary hemochromatosis-associated HFE gene allows us to study the molecular basis of congenital and acquired iron overload disorders. In hereditary hemochromatosis an increased frequency of the C282Y and, to a lesser extent, of the H63D mutations has been established, but their role in other conditions associated with iron overload and their prevalence in the normal population are still under investigation. We sought to determine the presence of such mutations, and their possible involvement in the multi-step neoplastic transformation of the hepatocytes, in patients diagnosed with hepatocellular carcinoma, a frequent complication of iron-induced liver cirrhosis occurring in untreated hereditary hemochromatosis subjects. The frequency of the C282Y and H63D mutations was determined in DNA from 12 patients with hepatocellular carcinoma and with no clinical signs of hereditary hemochromatosis. The frequency of the mutations was also determined in 130 normal subjects. A germline C282Y mutation was found in none of the hepatocellular carcinoma patients; the frequency of the H63D mutation was not increased, compared to the 130 controls. The allele frequencies of the C282Y and H63D mutations in the normal population were 0.042 and 0.185, respectively. In conclusion, we suggest that the hereditary hemochromatosis-related mutations of the HFE gene do not play a significant role in the pathogenesis of hepatocellular carcinoma.

Cloning of the hereditary hemochromatosis gene: Implications for pathogenesis, diagnosis, and screening

Hereditary hemochromatosis (HH) is one of the most common genetic disorders affecting populations of European ancestry. It is characterized by an inappropriately high iron absorption that leads to iron overload preferentially in the parenchymal organs. Although the severity of the phenotype can be modified by a number of factors, it is clear that most homozygotes will eventually become symptomatic. Clinical manifestations are often nonspecific and easily overlooked. Untreated HH can be associated with substantial morbidity and mortality. Diagnosis in the precirrhotic stage, however, results in normal life expectancy. Early diagnosis and the initiation of phlebotomy therapy are therefore keys to preventing complications related to iron overload. The recent isolation of a strong candidate gene for hemochromatosis has the potential to allow for genetic diagnosis and screening in the near future. This exciting finding is likely not only to change clinical practice but also to yield new insights into the poorly understood pathophysiology of the disease.

The Immune System in Hereditary Hemochromatosis: A Quantitative and Functional Assessment of the Cellular Arm

The objective of this investigation was to evaluate certain quantitative and functional characteristics of the effector cells of the cellular arm of the immune system in hereditary hemochromatosis (HH) with respect to treatment status. Two observations were consistent with the postulate that the elevated levels of storage iron has in vivo immunoregulatory properties: (1) the absolute number of CD8-positive T cells were significantly elevated in untreated HH patients (n = 7) and reduced in treated patients (n = 7), as compared with controls; and (2) the proliferative response of peripheral blood mononuclear cells from untreated HH patients to mitogens was suboptimal but the response of peripheral blood mononuclear cells (PBM) from treated HH patients was normal. Furthermore, immunoglobulin secretion by PBM from treated HH patients as compared to controls was altered. Finally, one T effector cell abnormality was unrelated to treatment status in that a subset of mature, non-activated T lymphocytes aberrantly formed thermostable erythrocyte-rosettes (TE-R), a lymphoid surface marker usually expressed on thymocytes or activated T cells. Taken together these data define certain immune alterations that are consistent with the interpretation that cellular immunity may be influenced by the high level of storage iron in HH patients.

Regulation of the hepatic transferrin receptor in hereditary hemochromatosis.

The liver is the main site of iron accumulation and pathologic sequelae in hereditary hemochromatosis. Whether this is a result solely of inappropriately increased absorption of iron by the gastrointestinal tract or a more generalized regulatory failure of iron balance is unknown. Using immunohistochemical techniques, we have examined the effects of therapeutic changes in liver iron stores on the expression of the hepatic transferrin receptor in hereditary hemochromatosis. Ten patients with untreated hereditary hemochromatosis had no detectable staining for transferrin receptor in their liver biopsies. All had increased hepatic ferritin (mean = 19.9 micrograms per mg protein, range = 1 to 31.7 micrograms per mg protein) and hepatic iron levels (mean = 36.2 micrograms per mg protein, range = 3.6 to 69.9 micrograms per mg protein). In contrast, hepatocyte transferrin receptor was detected in seven patients in whom hepatic iron stores were markedly depleted by venesection (hepatic ferritin mean = 0.32 microgram per mg protein, range = 0.16 to 0.53 microgram per mg protein; hepatic iron mean = 0.98 microgram per mg protein, range = 0.3 to 2.1 micrograms per mg protein). Sequential data from one patient confirmed the reexpression of receptor in response to therapeutic iron depletion, whereas data from another patient studied during treatment illustrated a reciprocal relationship between liver tissue distribution of iron and expression of transferrin receptor. The finding that appropriate physiologic regulation of the hepatic transferrin receptor operates in hereditary hemochromatosis does not support the concept of a generalized defect in receptor-mediated uptake of transferrin-bound iron.

Low Serum 25-Hydroxyvitamin in Hereditary Hemochromatosis:Relation to Iron Status

Under normal conditions, vitamin D absorbed from the diet or synthesized in the skin is transported to the liver where it undergoes hydroxylation. The purpose of this study was to determine whether excess hepatic iron affects this process and the subsequent production of 1,25-dihydroxyvitamin D (1,25-[OH]2D) in the kidney. Mean serum 25-hydroxyvitamin D (25-OHD) concentrations in untreated hereditary hemochromatosis were 13 +/- 6 (SD) in 9 patients with cirrhosis, 13 +/- 6 in 5 patients with hepatic fibrosis, and 22 +/- 6 in 10 patients with normal hepatic architecture aside from siderosis and were significantly lower than the levels found in 24 controls matched for age, sex, and season, p less than 0.05. The mean serum 25-OHD levels in the two groups with hemochromatosis and hepatic damage were significantly lower than the value in the group with normal hepatic architecture, p less than 0.05. Serum 25-OHD levels in individual patients were inversely related to the size of body iron stores as measured by exchangeable body iron, r = -0.64, or serum ferritin, r = -0.47, p less than 0.05. In 15 patients removal of excess body iron by venesection therapy produced a significant increase in the mean serum 25-OHD from 20 ng/ml to 30 ng/ml, p less than 0.05. In contrast, mean serum 1,25-[OH]2D levels were similar in iron-loaded and control subjects, indicating that the regulation of this metabolite was intact in patients with hemochromatosis. The results reveal that the low serum 25-OHD concentration in patients with hemochromatosis is directly related to the extent of iron loading and it is improved by venesection therapy.

Magnetic-susceptibility measurement of human iron stores.

We made direct noninvasive magnetic measurements of hepatic iron stores with a specially designed superconducting quantum-interference-device (SQUID) susceptometer in 20 normal subjects and in 110 patients with liver disease, iron deficiency, hereditary hemochromatosis, or transfusional iron overload. Magnetic in vivo measurements of liver non-heme iron were closely correlated with chemical in vitro measurements in liver-biopsy specimens (r = 0.98, P less than 10(-5) up to 115 mumol per gram of liver tissue (wet weight) or more. Magnetically determined storage-iron concentrations were below 6.0 mumol per gram in iron-deficient patients and normal men and premenopausal women, but they were raised (9.7 to 31.4 mumol) in 12 of 67 patients with liver disease and were greatly increased (22.9 to 117.7 mumol) in patients with untreated hereditary hemochromatosis or transfusional iron overload. Magnetic measurements of iron stores provide a new quantitative technique for early detection of hereditary hemochromatosis and for rapid evaluation of treatment regimens for transfusional iron overload.