Screening for hemochromatosis

Health Economic Evaluations of Hemochromatosis Screening and Treatment: A Systematic Review

BACKGROUND

Hereditary hemochromatosis (HH) is an autosomal recessive disorder that leads to iron overload and multiorgan failure.

OBJECTIVES

The aim of this systematic review was to provide up-to-date evidence of all the current data on the costs and cost effectiveness of screening and treatment for HH.

METHODS

We searched PubMed, Cochrane Library, National Health Service Economic Evaluation Database (NHSEED), Cost-Effectiveness Analysis Registry (CEA Registry), Health Technology Assessment Database (HTAD), Centre for Reviews and Dissemination (CRD), and Econlit until April 2023 with no date restrictions. Articles that reported cost-utility, cost-description, cost-minimization, cost-effectiveness, or cost-benefit analyses for any kind of management (drugs, screening, etc.) were included in the study. Patients with HH, their siblings, or individuals suspected of having HH were included in the study. All screening and treatment strategies were included. Two authors assessed the quality of evidence related to screening (either phenotype or genotype screening) and treatment (phlebotomy and electrophoresis). Narrative synthesis was used to analyse the similarities and differences between the respective studies.

RESULTS

Thirty-nine papers were included in this study. The majority of the studies reported both the cost of phenotype screening, including transferrin saturation (TS), serum ferritin, and liver biopsy, and the cost of genotype screening (HFE screening, C282Y mutation). Few studies reported the cost for phlebotomy and erythrocytapheresis treatment. Data revealed that either phenotype or genotype screening were cost effective compared with no screening. Treatment studies concluded that erythrocytapheresis might be a cost-effective therapy compared with phlebotomy.

CONCLUSIONS

Economic studies on either the screening, or treatment strategy for HH patients should be performed in more countries. We suggest that cost-effectiveness studies on the role of deferasirox in HH should be carried out as an alternative therapy to phlebotomy.

Cardiovascular manifestations in hospitalized patients with hemochromatosis in the United States

BACKGROUND

Heart complications are the main cause of morbidity and mortality in hemochromatosis, but the liver is the main site for iron deposition in these patients. Large multicenter studies have described cardiovascular (CV) manifestations in patients with secondary hemochromatosis. However, the overall prevalence and risk of CV manifestations in patients with hemochromatosis at the population level are unknown.

OBJECTIVE

To examine the prevalence and risk of CV manifestations in patients with hemochromatosis.

METHODS

A retrospective cohort from the National Inpatient Sample database between 2012 and 2014 was studied. We identified hemochromatosis using ICD-9-CM diagnostic codes. CV manifestations were defined by the presence of conduction disorders, arrhythmias, congestive heart failure (CHF), pulmonary hypertension, and non-ischemic cardiomyopathy (NISCM).

RESULTS

Of the 63,846,188 weighted hospitalizations that met the inclusion criteria, 64,590 (0.1%) had hemochromatosis and 13,200,000 (20.7%) had one or more CV manifestations. Of those with hemochromatosis, 5.3% had primary and 94.7% had secondary hemochromatosis. 27.8% of all hemochromatosis patients had one or more CV manifestations, 16% cardiac arrhythmias, 10.6% supraventricular arrhythmias (SVA), 0.8% ventricular arrhythmias, 9.3% CHF, 7.4% pulmonary hypertension, 4.2% NISCM, 2% conduction disorders, and 0.4% cardiac arrest. SVA (14.6% vs 10.4%, P < 0.001) was more prevalent in primary hemochromatosis compared to secondary while pulmonary hypertension (7.7% vs 2.6%, P < 0.001) was more prevalent in secondary hemochromatosis compared to primary. In multivariate modelling, only the adjusted odds of composite CV manifestations (odds ratio [OR] 1.24, 95% confidence interval [CI]: 1.03-1.48, P < 0.05) and SVA (OR 1.59, 95% CI: 1.28-1.96, P < 0.001) were significantly higher in patients with primary hemochromatosis compared with patients without hemochromatosis. In patients with secondary hemochromatosis, the adjusted odds of composite CV manifestations (OR 1.84, 95% CI: 1.74-1.95, P < 0.001), CHF (OR 1.46, 95% CI: 1.35-1.57, P < 0.001), conduction disorder (OR 1.52, 95% CI: 1.33-1.73, P < 0.001), pulmonary hypertension (OR 4.43, 95% CI: 3.97-4.94, P < 0.001), SVA (OR 1.39, 95% CI: 1.29-1.48, P < 0.001), and NISCM (OR 1.98, 95% CI: 1.79-2.20, P < 0.001) were significantly higher compared with patients without hemochromatosis.

CONCLUSION

Supraventricular arrhythmias, congestive heart failure, and pulmonary hypertension were the most common CV disorders in hemochromatosis patients. Risk-adjusted burden of supraventricular arrhythmias was significantly higher in primary and secondary hemochromatosis while patients with secondary hemochromatosis had a higher risk of congestive heart failure, pulmonary hypertension, conduction disorders, and non-ischemic cardiomyopathy.

HFE Genotype, Ferritin Levels and Transferrin Saturation in Patients with Suspected Hereditary Hemochromatosis

HFE hemochromatosis is characterized by increased iron absorption and iron overload due to variants of the iron-regulating HFE gene. Overt disease is mainly associated with homozygosity for the C282Y variant, although the H63D variant in compound heterozygosity with C282Y (C282Y/H63D) contributes to disease manifestation. In this observational study, we describe the association between biochemical findings, age, gender and HFE genotype in patients referred from general practice to a tertiary care referral center for diagnostic workup based on suspected hemochromatosis due to persistent hyperferritinemia and HFE variants. C282Y and H63D homozygosity were, respectively, the most and least prevalent genotypes and we found a considerable variation in transferrin saturation and ferritin levels independent of HFE genotype, which may indeed represent a diagnostic challenge in general practice. While our results confirm C282Y homozygosity as the major cause of iron accumulation, non-C282Y homozygotes also displayed mild to moderate hyperferritinemia with median ferritin levels at 500-700 µg/L, well above the reference cut-off. Such findings have traditionally been ignored in the clinic, and initiation of iron depletion has largely been restricted to C282Y homozygotes. Nevertheless, superfluous iron can aggravate pathogenesis in combination with other diseases and risk factors, such as inflammation, cancer and hepatopathy, and this possibility should not be neglected by clinicians.

Chelating Polymers for Hereditary Hemochromatosis Treatment

Hemochromatosis (iron overload) encompasses a group of diseases that are characterized by a toxic hyperaccumulation of iron in parenchymal organs. Currently, only few treatments for this disease have been approved; however, all these treatments possess severe side effects. In this study, a paradigm for hemochromatosis maintenance/preventive therapy is investigated: polymers with negligible systemic biological availability form stable complexes with iron ions in the gastrointestinal tract, which reduces the biological availability of iron. Macroporous polymer beads are synthesized with three different iron-chelating moieties (benzene-1,2-diol, benzene-1,2,3-triol, and 1,10-phenanthroline). The polymers rapidly chelate iron ions from aqueous solutions in vitro in the course of minutes, and are noncytotoxic and nonprooxidant. Moreover, the in vivo biodistribution and pharmacokinetics show a negligible uptake from the gastrointestinal tract (using ¹²⁵ I-labeled polymer and single photon emission computed tomography/computed tomography), which generally prevents them from having systemic side effects. The therapeutic efficacy of the prepared polymers is successfully tested in vivo, and exhibits a significant inhibition of iron uptake from the gastrointestinal tract without any noticeable signs of toxicity. Furthermore, an in silico method is developed for the prediction of chelator selectivity. Therefore, this paradigm can be applied to the next-generation maintenance/preventive treatment for hemochromatosis and/or other diseases of similar pathophysiology.

Intrahepatic Iron Variation May Greatly Affect the Hepatic Iron Index

The quantitative hepatic iron index is considered the gold standard for the diagnosis of primary hemochromatosis. While intrahepatic variability in the amount of stainable iron in histologic sections of liver is well known, the quantitative variability has not been addressed. Eight native livers removed at transplantation for cirrhosis associated with hepatitis C were studied. Iron-stained sections from multiple different areas of each liver were examined, and small areas were graded for iron content on a scale of 0 to 4. The fragments of liver corresponding to these were then cut out of the corresponding section of the paraffin block and sent for iron quantitation. We found that marked quantitative heterogeneity in iron content (>260%) can exist in a given liver, leading, in two cases, to false positive results for the diagnosis of hemochromatosis. In addition, it was found that quantitative iron content did indeed linearly correlate with histologic grading. Thus, intrahepatic variation in iron content in a given liver is yet another reason to interpret the hepatic iron index with caution.

Transferrin Saturation: A Body Iron Biomarker

Iron is an essential element for several metabolic pathways and physiological processes. The maintenance of iron homeostasis within the human body requires a dynamic and highly sophisticated interplay of several proteins, as states of iron deficiency or excess are both potentially deleterious to health. Among these is plasma transferrin, which is central to iron metabolism not only through iron transport between body tissues in a soluble nontoxic form but also through its protective scavenger role in sequestering free toxic iron. The transferrin saturation (TSAT), an index that takes into account both plasma iron and its main transport protein, is considered an important biochemical marker of body iron status. Its increasing use in many health systems is due to the increased availability of measurement methods, such as calorimetry, turbidimetry, nephelometry, and immunochemistry to estimate its value. However, despite its frequent use in clinical practice to detect states of iron deficiency or iron overload, careful attention should be paid to the inherent limitations of the test especially in certain settings such as inflammation in order to avoid misinterpretation and erroneous conclusions. Beyond its usual clinical use, an emerging body of evidence has linked TSAT levels to major clinical outcomes such as cardiovascular mortality. This has the potential to extend the utility of TSAT index to risk stratification and prognostication. However, most of the current evidence is mainly driven by observational studies where the risk of residual confounding cannot be fully eliminated. Indeed, future efforts are required to fully explore this capability in well-designed clinical trials or prospective large-scale cohorts.

Infiltrative Cardiomyopathies

Infiltrative cardiomyopathies can result from a wide spectrum of both inherited and acquired conditions with varying systemic manifestations. They portend an adverse prognosis, with only a few exceptions (ie, glycogen storage disease), where early diagnosis can result in potentially curative treatment. The extent of cardiac abnormalities varies based on the degree of infiltration and results in increased ventricular wall thickness, chamber dilatation, and disruption of the conduction system. These changes often lead to the development of heart failure, atrioventricular (AV) block, and ventricular arrhythmia. Because these diseases are relatively rare, a high degree of clinical suspicion is important for diagnosis. Electrocardiography and echocardiography are helpful, but advanced techniques including cardiac magnetic resonance (CMR) and nuclear imaging are increasingly preferred. Treatment is dependent on the etiology and extent of the disease and involves medications, device therapy, and, in some cases, organ transplantation. Cardiac amyloid is the archetype of the infiltrative cardiomyopathies and is discussed in great detail in this review.

Transferrin saturation ratio and risk of total and cardiovascular mortality in the general population

BACKGROUND

The transferrin saturation (TSAT) ratio is a commonly used indicator of iron deficiency and iron overload in clinical practice but precise relationships with total and cardiovascular mortality are unclear.

PURPOSE

To better understand this relationship, we explored the association of TSAT ratio (serum iron/total iron binding capacity) with mortality in the general population.

METHODS

The relationships of TSAT ratio with total and cardiovascular mortality were explored in 15 823 subjects age 20 and older from the Third National Health and Nutrition Examination Survey (1988-94). All subjects had vital status assessed through to 2006.

RESULTS

During follow-up, 9.7% died of which 4.4% were from cardiovascular disease. In unadjusted analysis, increasing TSAT ratio was inversely associated with mortality. With adjustment for baseline demographic and clinical characteristics, the TSAT-mortality relationship followed a j-shaped pattern. Compared with the referent group [ratio 23.7-31.3%: hazard ratio (HR) =1.00], subjects in the lowest two quartiles, <17.5 % and 17.5-23.7 %, experienced significantly higher mortality risks of 1.45 (1.19-1.77) and 1.27 (1.06-1.53), respectively, whereas subjects in the highest quartile, >31.3 %, experienced significantly higher mortality risks of 1.23 (1.01-1.49). The pattern of association was more pronounced for cardiovascular mortality with significantly higher mortality risks for the lowest two quartiles [HR = 2.09 (1.43-3.05) and 1.90 (1.33-2.72), respectively] and highest quartile HR = 1.59 (1.05-2.40).

CONCLUSIONS

Both low and high TSAT ratios are significantly and independently associated with increased total and cardiovascular mortality. The optimal TSAT ratio associated with the greatest survival is between 24% and 40%.

Transferrin saturation and hospital length of stay and mortality in Medicare beneficiaries

OBJECTIVES

To evaluate in a large, nationally representative cohort the association between high serum transferrin saturation (TS) and hospital length of stay and mortality in older adults.

DESIGN

Prospective cohort.

SETTING

Longitudinal analyses of the Third National Health and Nutrition Examination Survey linked to Medicare claims from 1991 through 2006.

PARTICIPANTS

Medicare beneficiaries aged 65 and older at baseline.

MEASUREMENTS

Transferrin saturation collected on each participant at baseline was characterized as <20.0%, 20.0% to 54.9%, and 55.0% and greater. Length of stay in the hospital and death in the hospital were primary outcomes. Analyses were adjusted for age, sex, race and ethnicity, education, and severity of illness.

RESULTS

Individuals hospitalized during the study period (79.4%) with high (odds ratio (OR) = 2.54, 95% confidence interval (CI) = 1.05-6.12) or low (OR = 1.31, 95% CI = 1.07-1.62) TS had a significantly greater risk of death than those with moderate TS. Individuals with high TS had longer average length of stay per hospitalization (11.1 days, (standard error, SE 1.7 days), P = .01) than those with moderate TS (8.4 (0.3) days). Individuals with high TS also had more hospital days per year (8.6 (2.0) days, P = .04) than those with moderate TS (6.7 (0.5) days).

CONCLUSION

High TS is associated with longer length of stay and death in the hospital (unweighted N = 3,847, weighted N = 28,395,464).

Iron homeostasis and eye disease

BACKGROUND

Iron is necessary for life, but excess iron can be toxic to tissues. Iron is thought to damage tissues primarily by generating oxygen free radicals through the Fenton reaction.

METHODS

We present an overview of the evidence supporting iron's potential contribution to a broad range of eye disease using an anatomical approach.

RESULTS

Iron can be visualized in the cornea as iron lines in the normal aging cornea as well as in diseases like keratoconus and pterygium. In the lens, we present the evidence for the role of oxidative damage in cataractogenesis. Also, we review the evidence that iron may play a role in the pathogenesis of the retinal disease age-related macular degeneration. Although currently there is no direct link between excess iron and development of optic neuropathies, ferrous iron's ability to form highly reactive oxygen species may play a role in optic nerve pathology. Lastly, we discuss recent advances in prevention and therapeutics for eye disease with antioxidants and iron chelators.

GENERAL SIGNIFICANCE

Iron homeostasis is important for ocular health.

Iron-overload-related disease in HFE hereditary hemochromatosis

BACKGROUND

Most persons who are homozygous for C282Y, the HFE allele most commonly asssociated with hereditary hemochromatosis, have elevated levels of serum ferritin and transferrin saturation. Diseases related to iron overload develop in some C282Y homozygotes, but the extent of the risk is controversial.

METHODS

We assessed HFE mutations in 31,192 persons of northern European descent between the ages of 40 and 69 years who participated in the Melbourne Collaborative Cohort Study and were followed for an average of 12 years. In a random sample of 1438 subjects stratified according to HFE genotype, including all 203 C282Y homozygotes (of whom 108 were women and 95 were men), we obtained clinical and biochemical data, including two sets of iron measurements performed 12 years apart. Disease related to iron overload was defined as documented iron overload and one or more of the following conditions: cirrhosis, liver fibrosis, hepatocellular carcinoma, elevated aminotransferase levels, physician-diagnosed symptomatic hemochromatosis, and arthropathy of the second and third metacarpophalangeal joints.

RESULTS

The proportion of C282Y homozygotes with documented iron-overload-related disease was 28.4% (95% confidence interval [CI], 18.8 to 40.2) for men and 1.2% (95% CI, 0.03 to 6.5) for women. Only one non-C282Y homozygote (a compound heterozygote) had documented iron-overload-related disease. Male C282Y homozygotes with a serum ferritin level of 1000 mug per liter or more were more likely to report fatigue, use of arthritis medicine, and a history of liver disease than were men who had the wild-type gene.

CONCLUSIONS

In persons who are homozygous for the C282Y mutation, iron-overload-related disease developed in a substantial proportion of men but in a small proportion of women.

Iron overload in the liver diagnostic and quantification

Hereditary Hemochromatosis is the most frequent modality of iron overload. Since 1996 genetic tests have facilitated significantly the non-invasive diagnosis of the disease. There are however many cases of negative genetic tests that require confirmation by hepatic iron quantification which is traditionally performed by hepatic biopsy. There are many studies that have demonstrated the possibility of performing hepatic iron quantification with Magnetic Resonance. However, a consensus has not been reached yet regarding the technique or the possibility to reproduce the same method of calculus in different machines. This article reviews the state of the art of the question and delineates possible future lines to standardise this non-invasive method of hepatic iron quantification.

Targeted screening for genetic haemochromatosis: a combined phenotype/genotype approach

OBJECTIVE

To evaluate the clinical utility of a targeted screening approach for the detection of genetic haemochromatosis.

METHODS

Screening by measuring fasting serum transferrin saturation (TS) and gene testing was carried out in patients in whom a raised serum alanine amino transferase (ALT) activity and raised random serum TS had been found on routine blood testing.

RESULTS

During the 29 month study period, 32 patients homozygous for the C282Y genotype were detected from a catchment population of 330,000 by screening blood samples referred initially for routine laboratory liver function tests. By comparison, during the same period of time and within the same population, only seven patients were found by clinical suspicion alone. The patients in the study, after treatment by venesection, have shown both clinical and biochemical improvement.

CONCLUSIONS

The study shows that from a population of patients in whom a routine liver function profile had been requested, it is possible to detect subjects homozygous for the C282Y HFE genotype who have clinical or biochemical markers of iron overload.

Revisiting hereditary hemochromatosis: current concepts and progress

Originally regarded as a rare affliction notable for its distinctive evolution to "bronze diabetes," hereditary hemochromatosis is now recognized as the most common genetic disorder in populations of European ancestry. Recent advances in our understanding of iron metabolism, the identification of the gene responsible for hemochromatosis, and large epidemiologic studies have changed the diagnostic approach toward patients with hereditary hemochromatosis and other forms of iron overload. This article reviews the pathophysiology, epidemiology, clinical features, diagnostic testing, and management of hemochromatosis for the primary care provider.

The role of hereditary hemochromatosis in aseptic loosening following primary total hip arthroplasty

Hereditary hemochromatosis (HH) results in increased iron absorption and subsequent deposition in tissue. This condition occurs predominantly in individuals of Northern European and Celtic origin with Ireland having one of the highest allele frequencies in the world. This study examines the hypothesis that homozygosity for either the C282Y or H63D mutations in the HFE gene may be associated with aseptic loosening following total hip arthroplasty (THA). Two groups of individuals were screened for the C282Y and H63D mutations associated with HH. Group 1 were individuals who had undergone primary hip arthroplasty and group 2 were individuals who had undergone revision hip arthroplasty for aseptic loosening. Exclusion criteria included rheumatoid or other inflammatory arthropathies and revision due to causes other than aseptic loosening. Significantly more patients in the revision THA group were homozygous for the C282Y genotype (P = 0.014). Aseptic loosening occurred earlier in these patients (P = 0.009), in particular in the patients who had clinical signs of hemochromatosis. No association was seen with the H63D mutation and revision THA. The incidence of HH in the group of primary THA patients was no higher than the background incidence. Patients who require primary THA and who are homozygous for the C282Y mutation have an increased risk of developing aseptic loosening, leading to revision THA. Moreover C282Y homozygosity appears to be associated with earlier aseptic loosening than in individuals without the C282Y mutation.

Soluble transferrin receptor in hemochromatosis patients during phlebotomy therapy

BACKGROUND

The monitoring of phlebotomies in hemochromatosis patients depends on iron status measured by ferritin and transferrin saturation (TS). However, in the presence of inflammation or liver injury, soluble transferrin receptor (sTfR) determination was proposed to replace ferritin for diagnosing iron deficiency (ID). The present study evaluated performances of sTfR for the prediction of iron deficiency in a large number of hemochromatosis patients under phlebotomy therapy.

METHODS

We studied 52 patients undergoing therapeutic phlebotomies and obtained 2 samples from 37 patients. Biological parameters were determined before each phlebotomy began. Performances of sTfR and TS in the diagnosis of iron deficiency were compared, according to ferritin levels under 12 microg/l.

RESULTS

Ferritin and TS were correlated with removed iron (r=0.473, p<0.005 and r=0.345, p<0.05, respectively) and sTfR was correlated with the decrease in hemoglobin levels induced by phlebotomies (r=-0.678, p<0.0001). Areas under Receiver Operating Characteristics (ROC) curves for sTfR and TS were not statistically different for prediction of iron deficiency and sensitivity/specificity of sTfR at 1.64 mg/l were 67/86%.

CONCLUSIONS

sTfR determination could be used to predict iron depletion induced by phlebotomies when ferritin is of limited interest, to avoid the appearance of anemia.

Transferrin saturation, dietary iron intake, and risk of cancer

PURPOSE

Transferrin saturation of more than 60% has been identified as a cancer risk factor. It is unclear whether dietary iron intake increases the risk of cancer among individuals with transferrin saturation of less than 60%. The purpose of this study was to examine the association of dietary iron intake and the risk of cancer among adults with increased transferrin saturation.

METHODS

Analysis of a cohort study, the National Health and Nutrition Examination Survey I Epidemiologic Follow-Up Study, was performed. US adults (aged 25 to 74 years at baseline) were followed up from baseline in 1971-1974 to 1992 (N = 6,309).

RESULTS

A total of 7.3% of the US population had a serum transferrin saturation of more than 45% at baseline. Intake of dietary iron was essentially uncorrelated with transferrin saturation (r = 0.04). Compared with individuals who had normal serum transferrin saturation and low dietary iron intake, individuals whose serum transferrin saturation was more than 45% and who had high dietary iron intake also had an increased adjusted relative risk of cancer (2.24; 95% confidence interval [CI], 1.02-4.89). Increased risk was not found for individuals with a transferrin saturation of more than 45% but a normal dietary iron intake (hazard ratio, 1.02; 95% CI, 0.69-1.49). Transferrin saturation levels could be set as low as 41%, and the individuals with high transferrin saturation and high dietary iron intake would still have an increased adjusted relative risk of cancer (hazard ratio, 2.00; 95% CI, 1.04-3.82).

CONCLUSIONS

Among persons with increased transferrin saturation, a daily intake of dietary iron more than 18 mg is associated with an increased risk of cancer. Future research might focus on the benefits of dietary changes in those individuals with increased serum transferrin saturation.

Analysis of HFE and TFR2 gene mutations in patients with acute leukemia

There are increasing evidences regarding the association between iron overload and extra-hepatic malignancies. We studied the prevalence of 12 hereditary hemochromatosis (HH) gene mutations (C282Y, V53M, V59M, H63D, H63H, S56C, Q127H, E168Q, E168X, W169X and Q283P in the HFE gene and Y250X in the TFR2 gene) and its correlation with the iron status in 82 adult patients with acute leukemia (AL); 48 patients (58.5%) were affected by acute myeloid leukemia (AML) and 34 patients (41.5%) by acute lymphoblastic leukemia (ALL); 27 patients (32.9%) had at least one HH gene mutation (6 heterozygous for C282Y, 6 homozygous for H63D, 13 heterozygous for H63D and 2 heterozygous for S56C). Mean serum ferritin levels at diagnosis were increased (822.5+/-811.4 microg/L). However, there was no difference between patients positive or negative for the HH gene mutations. Similarly, we did not observe any statistically significant difference as far as iron status between AML and ALL patients. Our study does not support the evidence of an association between hemochromatosis gene mutations and iron overload in AL patients.

Male hypogonadism in the primary care clinic

Hypogonadism is common in clinical practice but is frequently unrecognized and underdiagnosed. The common causes of male hypogonadism vary with the age of presentation. The overall prevalence of male hypogonadism based upon low serum total testosterone levels is high and increases with age. There are many pitfalls in making the diagnosis of male hypogonadism. First, male hypogonadism is sometimes difficult to recognize because the signs and symptoms are often nonspecific and overlap with other common syndromes. Second, the biochemical diagnosis of male hypogonadism is not straightforward because it might not be clear which testosterone assay to select from the many that are available. Finally, even after the diagnosis of male hypogonadism is made, the patient and clinician must weigh the potential benefits and risks of androgen replacement therapy. However, new diagnostic tools and therapies are making decisions easier.

Reflective testing: how useful is the practice of adding on tests by laboratory clinicians?

AIMS

To investigate the clinical value and practice of reflective testing, a new term to describe the practice of adding on tests when reporting or clinically authorising results.

METHODS

A consultant medical biochemist collected over a calendar year (2001) copies of clinical biochemistry reports on samples to which he had added on either iron studies (iron, total iron binding capacity (TIBC), and percentage saturation), or vitamin D. Iron studies and vitamin D were added on when biochemical results, available clinical information, demographic data, and clinical experience-or combinations thereof-suggested the possibility of haemochromatosis or vitamin D deficiency, respectively. The number of reports that the consultant authorised was estimated for the same calendar year. The number and percentage of raised TIBC percentage saturation and low vitamin D results from the tests that were added on were collated.

RESULTS

Raised TIBC saturation values were found in 28 patients (18.7% of the iron studies added on), of whom 16 were subsequently genotyped, eight having a genotype consistent with haemochromatosis. Thirty one patients with vitamin D deficiency (23.1% of the vitamin D tests added on) were identified.

CONCLUSIONS

The addition of iron studies and vitamin D tests by a laboratory clinician, when reporting, resulted in the identification of patients with haemochromatosis and vitamin D deficiency. The practice of adding on tests should be called reflective testing, because it is discretionary and is based on the clinical judgement of a laboratory clinician in the interpretation of results.

Elevated serum transferrin saturation and mortality

BACKGROUND

A large proportion of US adults have elevated transferrin saturation, an indicator of a predisposition for iron overload. The purpose of this study was to evaluate the relationship between elevated serum transferrin saturation and mortality.

METHODS

This cohort study was conducted using data from the First Health and Nutrition Examination Survey 1 (1971-1974) (NHANES I) merged with the NHANES I Epidemiologic Followup Study (1992) (N = 10,714). We used SUDAAN and appropriate weights to make population estimates for the adult US population (aged 25 to 74 years at baseline). All-cause mortality was evaluated in relation to serum transferrin saturation of greater than 45%, greater than 50%, greater than 55%, and greater than 60% using Cox proportional hazards regression.

RESULTS

In a Cox proportional hazards model controlling for potential confounders, including comorbid diseases, smoking, and cholesterol, all-cause mortality is significantly greater for persons with a serum transferrin saturation of more than 55%, compared with those with saturations below this cutoff (hazards ratio [HR] = 1.60, 95% confidence interval [CI], 1.17-2.21). No one who died had hemochromatosis as any of the 20 listed causes of death. Many of the underlying causes of death for persons with serum transferrin saturation levels of more than 55% are common causes of death in the general population, although these persons were more likely to have died of cirrhosis and diabetes, a finding consistent with iron overload.

CONCLUSIONS

In this nationally representative cohort of adults, those with elevated serum transferrin saturation, more than 2% of the adult US population, were at increased risk for all-cause mortality.

Coeliac disease and hereditary haemochromatosis: association and implications

Coeliac disease and hereditary haemochromatosis are genetic disorders paradoxically associated with altered intestinal absorption of iron. Hereditary haemochromatosis is the most common autosomal recessive disease in the Caucasian population and is characterised by an iron overload state. Coeliac disease, or gluten sensitive enteropathy, on the other hand is frequently associated with iron deficiency anaemia. We report the cases of two patients who developed both coeliac disease and hereditary haemochromatosis. We review the literature of this rare association and examine how the clinical presentation is modified by their co-existence and the potential genetic linkage of these two disorders.

Screening for iron overload in the Turkish population

BACKGROUND/AIMS

Hereditary hemochromatosis (HH), the most common autosomal recessive disease in the white population, is characterized by excessive gastrointestinal absorption of iron and loading of parenchymal organs. HFE mutations of C282Y and H63D are largely responsible for HH in populations of Celtic ancestry. Although many screening studies related to HH have been done in Northern Europe, the USA and Australia, as yet, no such study has been published on Turkey. In this study we aimed to screen the Turkish population for iron overload.

METHODS

Random samples were obtained from 4,633 healthy adults (3,827 male, 806 female, mean age +/- SD 35 +/- 8 years, range 14-76) for the measurement of transferrin saturation (TS). Measurements were repeated after an overnight fast in the subjects whose initial TS was > or =50%. Serum ferritin levels and C282Y and H63D gene mutations were studied in cases when fasting TS was > or =50%. In cases where the serum ferritin level was >200 ng/ml with or without HFE mutations, liver biopsy was performed for histological evaluation and determination of iron content.

RESULTS

In 158 subjects, TS was > or =50% in the non-fasting state. A second determination of TS after an overnight fast was performed in 135 subjects. In 26 subjects, the TS was > or =50% in the fasting state. HFE mutation and serum ferritin levels were measured in these 26 subjects. Eleven subject (10 male, 1 female) were heterozygote and 1 male subject was homozygote in reference to H63D. C282Y mutation was not found. Four of these 26 subjects (all males, aged 23, 24, 40, 49) had increased serum ferritin levels and liver biopsy was performed. In 1 male (aged 49) who was heterozygote for H63D genotype with a serum ferritin level of 645 ng/ml, iron overload in liver tissue was shown by histology as well as atomic absorption spectrophotometry.

CONCLUSION

The prevalence of hemochromatosis in the Turkish population is much lower in comparison to populations of Celtic ancestry and C282Y mutation is non-existent.

Genetics of haemochromatosis

After identification of the hereditary haemochromatosis gene HFE, and receipt of confirmation that most patients with the condition were homozygous for a single, founder mutation (C282Y), most assumed that C282Y would be a prevalent, highly penetrant mutation in a gene that plays a key part in the regulation of iron absorption and of whole-body iron homoeostasis. With carrier rates of between 10% and 15%, and a homozygote frequency of about one-in-150 in people of northern European descent, C282Y is certainly prevalent. However, it is not highly penetrant. The pronounced variation in phenotype in individuals with the same gene mutation has prompted the search for modifier genes at other loci, and for environmental factors that might affect expression of the condition. Progress in our understanding of how HFE regulates the absorption of dietary iron has been slow, but much can be learnt from the study of the rare instances of haemochromatosis that involve mutations in newly-identified iron-metabolism genes, such as TFR2--a transferrin receptor isoform--and ferroportin1/Ireg1/mtp1--an intestinal iron transporter. The availability of definitive information on penetrance and the identity of genetic modifiers will aid the debate on whether population screening for haemochromatosis should be undertaken or whether alternative strategies should be implemented to improve early detection.

Hereditary hemochromatosis

Hereditary hemochromatosis (hh, type 1 hemochromatosis) is an autosomal recessive trait characterized by hyperabsorption of dietary iron. The disease trait occurs in approximately five per thousand Caucasians of northern European descent. The causative gene, designated HFE, was isolated and characterized in 1996; most individuals with hh are homozygous for a mutation resulting in a change from cysteine to tyrosine at residue 282 of the HFE protein (C282Y). Wild-type HFE protein binds to the transferrin receptor, and by an undefined mechanism the enterocyte is "programmed" to absorb an amount of dietary iron precisely matched to the body's needs. The C282Y mutant protein is not expressed on the cell surface and does not bind to the transferrin receptor; the result is an enterocyte programmed to absorb slightly more iron than required. Most individuals with hh display a common laboratory phenotype, an elevated transferrin saturation. Iron stores in excess of normal eventually occur in most men and some women. The prevalence of organ damage due to iron overload, however, remains a controversial issue. Published estimates range from less than 1% to "nearly all." The main reason for this discrepancy has been ascertainment bias. Retrospective studies have been biased in favor of individuals with morbid complications of hh, whereas screening studies of groups such as blood donors generally include only healthy subjects. We focus here on a review of studies that have attempted to avoid ascertainment bias. If biopsy-proven hepatic fibrosis and/or cirrhosis is employed as the single criterion for disease-related morbidity, clinical penetrance of hh occurs in 4% to 25% of homozygotes. This range, although narrower than in biased studies, is still wide and requires clarification. A large-scale population-based study has been sponsored by the National Institutes of Health to address this issue. Until results become available, the pragmatic approach is to continue to screen for hemochromatosis in the primary care setting and to maintain serum ferritin values at approximately 100 micro g/L or lower with phlebotomy therapy.

HFE based re-evaluation of heterozygous hemochromatosis

Homozygosity for the C282Y mutation in the HFE gene is strongly associated with hereditary hemochromatosis. More than one subject out of 10 in the general population is a heterozygote for the C282Y mutation. In this study, we address whether or not conclusions drawn from HLA-based family studies regarding the expression of heterozygous hemochromatosis are applicable to C282Y heterozygotes. The correlation between HLA-inferred and HFE genotypes and the variation of serum iron tests according to HFE genotype and other factors were studied in persons from well-characterized hemochromatosis pedigrees. Subjects were tested for both C282Y and H63D mutations. The following factors were studied: age, sex, alcohol consumption, body mass index, liver function tests, serum lipids and glucose, serum iron, transferrin saturation, and ferritin. HLA-inferred heterozygotes were C282Y heterozygotes in only 70% and compound heterozygotes (i.e., heterozygotes for both C282Y and H63D) in 20%. C282Y heterozygotes did not differ from wild type homozygotes in terms of serum iron tests. Only compound heterozygotes presented with slightly increased transferrin saturation. On the other hand, increased serum ferritin was strongly associated with overweight or lipidic or glucose abnormalities. C282Y heterozygotes selected from family studies do not have greater serum iron tests than wild type homozygotes, except for compound heterozygotes, and therefore should not require special followup. The discovery of abnormal iron tests in a C282Y heterozygote should lead to workup for other causes of iron overload.

Preserving the national blood supply

This paper examines the current state of the blood supply in the US and focuses on the potential for augmenting blood availability by attention to the iron status of donors. Increasing demands are being made upon the national blood supply as rates of blood donation are declining, in part because of the loss of blood donors as a result of enhanced screening and testing procedures. Iron-related means of expanding the blood supply include the use of blood from individuals undergoing therapeutic phlebotomy for hereditary hemochromatosis and enhancing the retention and commitment of women of childbearing age as donors by using iron supplementation to prevent iron deficiency. In Section I, Dr. Klein discuss the circumstances responsible for a decline in the population of eligible donors, including public attitudes toward donation, factors influencing the retention of donors by blood centers, and the effects of increased screening and testing to maintain the safety of the blood supply. In Section II, Drs. Kushner and Ajioka focus on the consequences of the decision by the US Food and Drug Administration (FDA) to develop recommendations to permit blood centers to collect blood from patients with hereditary hemochromatosis and to distribute this blood obtained without disease labeling if all other screening and testing procedures are passed. After summarizing the pathophysiology of hereditary hemochromatosis, the use by blood centers of blood obtained from heterozygotes and homozygotes for hereditary hemochromatosis is considered. In Section III, Dr. Brittenham reviews the use of low dose, short-term carbonyl iron supplementation for women donors of childbearing age. Replacing the iron lost at donation can help prevent iron deficiency in women of childbearing age and, by decreasing deferral, enhance the retention and commitment of women who give blood regularly. He emphasizes the use by blood centers of iron-related means to enhance recruitment and retention of blood donors.

Strategies for early diagnosis of haemochromatosis

Genetic haemochromatosis is one of the most frequent inborn errors of metabolism. Only patients with early non-cirrhotic haemochromatosis treated by phlebotomies have a normal life expectancy. The present review analyses strategies for early diagnosis of haemochromatosis by using the Medline database and own data from a large cohort of patients with haemochromatosis. The still widely used approach to look for haemochromatosis in the presence of clinical complications such as liver disease will detect haemochromatosis in a considerable percentage of patients with Celtic origin. However, up to one half of these patients will already have an irreversible complication such as liver cirrhosis, diabetes mellitus or cardiomyopathy. In contrast, screening approaches of non-selected asymptomatic subjects using either determination of transferrin saturation and serum ferritin (phenotypic screening) or using genetic testing will detect haemochromatosis in most subjects in a precirrhotic stage without irreversible complications. Both phenotypic and genetic screening are highly cost-effective for detection of iron-loaded individuals in the general population. The current clinical approach to look for haemochromatosis in the presence of clinical disease is unacceptable. Only a more general type of screening in asymptomatic subjects including genetic testing will increase the rate of early diagnosis and will further improve the clinical outcome.

Screening for hemochromatosis

BACKGROUND

Hereditary hemochromatosis is the most common autosomal recessive disorder in populations of northern European descent.

ISSUES

Many experts consider hemochromatosis to be an almost ideal disease for population screening because it essentially fulfills almost all the criteria for screening proposed by the WHO. However, others disagree and suggest that more data are required particularly with regard to the natural history and penetrance of the disease. There is also disagreement about the best diagnostic/screening test for the disease and the performance of these tests in the context of screening. Other concerns are the variability and lack of standardization in screening test measurements, the selection of screening threshold values and the identification of false positive cases. The advent of a genetic test for the condition has brought other worries with regard to informed consent and the ethical, legal and social implications of screening particularly in relation to medical and general discrimination. Other important issues include compliance, cost effectiveness and the evidence that screening has lessened the burden of disease in the community.

CONCLUSIONS

At the present time, we believe that further data regarding both the exact disease burden and the outcomes of screening studies particularly in the general community are required before widespread population screening is introduced.

Relationship between transferrin saturation and iron stores in the African American and US Caucasian populations: analysis of data from the third National Health and Nutrition Examination Survey

In previous analyses of transferrin saturation data in African Americans and Caucasians from the second National Health and Nutrition Examination Survey (NHANES II), subpopulations were found consistent with population genetics for common loci that influence iron metabolism. The goal of this new study was to determine if these transferrin saturation subpopulations have different levels of iron stores. Statistical mixture modeling was applied to transferrin saturation data for African Americans and Caucasians from the third National Health and Nutrition Examination Survey (NHANES III), and then the mean serum ferritin concentrations were determined for the transferrin saturation subpopulations that were identified. After adjustment for diurnal variation, 3 subpopulations of transferrin saturation were identified in each racial group. Satisfying Hardy-Weinberg conditions for major locus effects, in both racial groups the sum of the square roots of the proportion with the lowest mean transferrin saturation and the proportion with the highest mean transferrin saturation was approximately 1. When weighted to reflect the US adult population as a whole, these subpopulations of increasing transferrin saturations had progressively increasing mean age-adjusted serum ferritin concentration values in each ethnic grouping as stratified by sex (trend test, P <.002 for all). These results are consistent with the concept that population transferrin saturation subpopulations reflect different levels of storage iron.

Screening for hemochromatosis: high prevalence and low morbidity in an unselected population of 65,238 persons

BACKGROUND

Hereditary hemochromatosis (HH) is a common genetic disease leading to accumulation of iron in several organs, most notably the liver. The C282Y/C282Y mutation in the HFE gene is found in most cases. In order to prevent clinical disease and to study the cost and feasibility of screening, a large population was screened.

METHODS

In a Norwegian county, all inhabitants 20 years or older were invited to participate in a population-based health survey programme. Screening for HH was one of several subprojects. Blood samples were obtained from 65,238 persons. Subjects with high serum transferrin saturation in two tests and high serum ferritin were clinically evaluated for HH. All subjects with high serum transferrin saturation in two tests were offered genotyping.

RESULTS

HH was newly diagnosed in 92 women and 177 men. Phlebotomy treatment was performed in 64 women and 152 men. Severe organ damage (liver cirrhosis) was ascertained in only 4 men. We found no correlation between serum ferritin and age. The estimated cost was US$ 1.6 per subject screened and US$ 390 per newly discovered HH subject. The estimated prevalence of phenotypical HH not previously known was 0.34% in women and 0.68% in men. The prevalence of the C282Y/C282Y mutation was at least 0.68%.

CONCLUSION

Large-scale screening for HH can be performed at a relatively low cost if combined with a health survey programme. The yield in terms of newly discovered cases is considerable, but few cases were found seriously ill. Better knowledge of the natural course of HH is necessary if we are to be able to estimate the cost-effectiveness of large-scale screening.

MCV as a guide to phlebotomy therapy for hemochromatosis

BACKGROUND

A multitude of recommendations exist for laboratory assays to monitor the pace and endpoints of phlebotomy therapy for hemochromatosis. All of these recommendations rely on an assessment of storage iron to guide treatment, and none have been prospectively evaluated.

STUDY DESIGN AND METHODS

Nine consecutive patients underwent serial monitoring of Hb, MCV, transferrin saturation, and ferritin during weekly phlebotomy to deplete iron stores (induction therapy) and less frequent sessions to prevent iron reaccumulation (maintenance therapy). Changes in MCV and Hb were used to guide the pace of phlebotomy over a median of 7 years of follow-up.

RESULTS

During induction therapy, the MCV increased transiently because of reticulocytosis and then stabilized for a prolonged period before decreasing more sharply, which reflected iron-limited erythropoiesis. Iron depletion was achieved after a median of 38 phlebotomies and removal of 9.0 g of iron. Maintenance phlebotomy was targeted to maintain the MCV at 5 to 10 percent below prephlebotomy values and the Hb at >13 g per dL. Transferrin saturation fluctuated considerably during treatment, but remained below 35 percent during MCV-guided maintenance therapy. Ferritin values were not useful guides to the pace of phlebotomy. The median maintenance therapy phlebotomy interval was 7.5 weeks (range, 6-16), which corresponded to an average daily iron removal of 35 to 67 microg per kg. Most patients showed evidence of iron reaccumulation at phlebotomy intervals of 8 weeks or more.

CONCLUSION

The MCV is an inexpensive, precise, physiologic indicator of erythropoietic iron availability. When used in conjunction with the Hb, it is a clinically useful guide to the pace of phlebotomy therapy for hemochromatosis.

Genetic hemochromatosis: detection, management, and population screening

Genetic hemochromatosis (GH) is an inherited disease that results in iron overload, and, if untreated, causes irreversible organ damage. Knowledge and understanding of the early features of the condition, often nonspecific, and of the diagnostic route are necessary to detect iron overload and diagnose GH before irremedial damage has been done. Genetic testing now plays an important role in diagnosis. Management of the patient with established GH centers on venesection to return body iron levels to normal, treatment of the complications of GH, and family screening for GH. Population screening for GH, the ideal strategy to prevent any morbidity from iron overload, has not yet been accepted by public health professionals, largely because of the lack of data on the disease penetrance in genetically susceptible individuals.

Early detection of genetic hemochromatosis: should all young adults be offered the genetic test?

Genetic hemochromatosis (GH) is a late-onset, autosomal recessive disorder. The majority of those at risk from iron overload and its clinical consequences may be detected by a simple genetic test. Furthermore, treatment by phlebotomy, if instituted early, removes excess iron and prevents the complications of iron overload which include arthralgia, diabetes, and cirrhosis of the liver. GH seems to be an obvious candidate for inclusion in national screening programs. However, important questions remain concerning the proportion of individuals with the high-risk genotype who eventually show clinical manifestations of iron overload and the significance of heterozygosity for haemochromatosis in terms of morbidity. Until these questions are resolved, the introduction of widespread genetic screening cannot be justified.

Prevention in liver disease

Prevention has become an important component of medical therapy for a variety of diseases. Preventive strategies in liver disease are relatively underdeveloped and have focused mainly on specific complications of chronic liver disease and vaccination for viral hepatitis. Although public health initiatives designed to prevent certain forms of liver disease are in place, they seem to be underutilized and their utility has not been evaluated. The development of a comprehensive approach using public health initiatives in conjunction with strategies by health care providers is important because of the potential for decreasing the human and health care costs associated with hepatic dysfunction. This article reviews the available literature regarding prevention for health care providers, includes a summary of ongoing public health initiatives, and suggests an approach to prevention in liver disease. It is intended to raise awareness and encourage implementation of preventive strategies in hepatology.

Biochemical expression of heterozygous hereditary hemochromatosis

Background: Hereditary hemochromatosis (HH) is a common autosomal recessive disease caused by an iron overload. Two mutations (C282Y and H63D) on the responsible HFE gene have been described. HH heterozygotes may have a slight iron overload that does not cause clinical disease. Compound heterozygosity may be associated with higher iron stores than C282Y heterozygosity. We studied biochemical iron parameters in HH C282Y and compound heterozygotes without a clinically significant iron overload. Methods: Data on hemoglobin, hematocrit, mean corpuscular volume, serum ferritin, serum iron, transferrin, and transferrin saturation were obtained from 40 C282 wild type controls (irrespective of H63D genotype), 61 C282Y heterozygotes, and 18 compound (C282Y/H63D) heterozygotes without clinical iron overload disease. Results: Serum ferritin levels were significantly higher in female HH heterozygotes, particularly in compound heterozygotes, than in normal women. In male heterozygotes, no difference in serum ferritin was found. We found higher mean serum iron and transferrin saturation levels in male and female HH heterozygotes than in normal controls, the highest in the group of compound heterozygotes. Conclusions: Mean serum ferritin (only in women), serum iron, and transferrin saturation are highest in compound heterozygotes and lowest in controls. C282Y heterozygotes seem to be an intermediate group between compound heterozygotes and the normal population.

Transdermal estrogen replacement therapy in postmenopausal women previously treated for porphyria cutanea tarda

Oral contraceptives and postmenopausal estrogen replacement therapy are recognized as risk factors for the development of porphyria cutanea tarda (PCT) in women. The recommended clinical practice is to withhold estrogen therapy in women who have had phlebotomy therapy for PCT and are clinically and biochemically normal. We tested the safety and efficacy of transdermal estrogen replacement therapy in 7 women previously treated for PCT and compared them with 19 non-porphyric control subjects treated with transdermal or oral estrogens. Gonadotrophic hormone levels, estrogen levels, liver function studies, body iron stores, urine porphyrin excretion, and cytochrome P4501A2 (CYP1A2) activity were monitored for 1 year. Four of the women previously treated for PCT completed the study. None had evidence of a porphyric relapse. CYP1A2 activity, measured by three different methods, did not differ between study subjects receiving estrogens, patients with active PCT, and non-porphyric control subjects, nor did CYP1A2 activity change during the study period. Gonadotrophic hormone levels fell and estrogen levels rose in all women receiving estrogens. The administration of estrogens by the transdermal route appeared to be safe in the small number of subjects we studied and should be considered for women previously treated for PCT.