Transferrin in disease II: defects in the regulation of transferrin saturation with iron contribute to susceptibility to infection

Patients with leukemia were found to have a high percentage of saturation of their serum transferrin with iron to an extent only rarely observed with other malignancies. This was associated with a reduced ability of their serum to inhibit the growth of a test strain of Pseudomonas aeruginosa. Serum iron, transferrin, and related parameters were measured serially in patients undergoing bone marrow transplantation for leukemia or aplastic anemia. It was found that a high proportion of these patients also have a high saturation of their transferrin with iron. This was related to three distinct physiologic deficits: a low level of serum transferrin; a high level of iron; and an inability to reduce the level of serum iron during infection. Three of six patients who were unable to reduce their serum during fever and infection subsequently died of sepsis. These data support the hypothesis that derangements in nonspecific serologic defense mechanisms involving iron contribute to susceptibility to infection in patients with leukemia undergoing bone marrow transplantation.     

Serum ferritin and bone marrow iron stores. I. Correlation with absence of iron in biopsy specimens

Serum iron, total iron-binding capacity, and percentage saturation of transferrin have classically been used to demonstrate a hypoferremic state; however, these tests may not discriminate between depleted iron stores and conditions associated with defective reticuloendothelial release of iron. Estimation of stainable iron in the bone marrow biopsy specimen is then the most practical way to assess body iron stores. With the availability of a radioimmunoassay procedure for serum ferritin, we undertook a prospective study to determine whether serum ferritin concentrations might replace assessment of the marrow biopsy iron stores as an indicator of hypoferremia. Iron stores were absent from bone marrow biopsy specimens from 104 patients. A good correlation between low serum ferritin levels and absence of iron stores in biopsy specimens was found for 91 patients (87.5%). Thirteen (12.5%) had normal serum ferritin concentrations with absence of biopsy iron. These individuals had hematopoietic malignancies or active hepatic disease, or were receiving iron therapy. In this group, a bone marrow biopsy would still be necessary for evaluation of a hypoferremic state, even though the serum ferritin concentration might be normal.     

Normal serum ferritin concentrations in precirrhotic hemochromatosis.

We investigated 33 of 58 members of two families with latent or precirrhotic hemochromatosis to determine its pattern of inheritance and to evaluate the serum ferritin levels as an index of iron stores. In both families, the pattern of inheritance was as an autosomal dominant trait with incomplete expressivity. Mean serum ferritin values in the affected family members were 88.5 ng per milliliter (range, 28.0 to 201.9) for males and 65.2 ng per milliter (range 23.7 to 97.0) for females, which were no different from controls (P is less than 0.5). Furthermore, the serum ferritin values did not correlate with or reflect mobilizable iron stores, and there were no relations between the serum iron, iron-binding capacity and transferrin saturation (P is less than 0.2). Thus, serum ferritin concentrations in precirrhotic familial hemochromatosis appear to underestimate iron stores. Serum ferritin levels do not help to identify such patients with increased iron stores for therapeutic phlebotomy.     

A population-based study of the clinical expression of the hemochromatosis gene.

BACKGROUND AND METHODS: Hereditary hemochromatosis is associated with homozygosity for the C282Y mutation in the hemochromatosis (HFE) gene on chromosome 6, elevated serum transferrin saturation, and excess iron deposits throughout the body. To assess the prevalence and clinical expression of the HFE gene, we conducted a population-based study in Busselton, Australia. In 1994, we obtained blood samples for the determination of serum transferrin saturation and ferritin levels and the presence or absence of the C282Y mutation and the H63D mutation (which may contribute to increased hepatic iron levels) in 3011 unrelated white adults. We evaluated all subjects who had persistently elevated transferrin-saturation values (45 percent or higher) or were homozygous for the C282Y mutation. We recommended liver biopsy for subjects with serum ferritin levels of 300 ng per milliliter or higher. The subjects were followed for up to four years. RESULTS: Sixteen of the subjects (0.5 percent) were homozygous for the C282Y mutation, and 424 (14.1 percent) were heterozygous. The serum transferrin saturation was 45 percent or higher in 15 of the 16 who were homozygous; in 1 subject it was 43 percent. Four of the homozygous subjects had previously been given a diagnosis of hemochromatosis, and 12 had not. Seven of these 12 patients had elevated serum ferritin levels in 1994; 6 of the 7 had further increases in 1998, and 1 had a decrease, although the value remained elevated. The serum ferritin levels in the four other homozygous patients remained in the normal range. Eleven of the 16 homozygous subjects underwent liver biopsy; 3 had hepatic fibrosis, and 1, who had a history of excessive alcohol consumption, had cirrhosis and mild microvesicular steatosis. Eight of the 16 homozygous subjects had clinical findings that were consistent with the presence of hereditary hemochromatosis, such as hepatomegaly, skin pigmentation, and arthritis. CONCLUSIONS: In a population of white adults of northern European ancestry, 0.5 percent were homozygous for the C282Y mutation in the HFE gene. However, only half of those who were homozygous had clinical features of hemochromatosis, and one quarter had serum ferritin levels that remained normal over a four-year period.     

Comparison of haematological indices between women of four ethnic groups and the effect of oral contraceptives.

Six-hundred-and-eighty-two women volunteers from four ethnic groups--Black, Indian, Oriental and White took part in a study to assess differences in haematological indices between the groups. This study was part of a broad investigation into the metabolic effects of oral contraceptives. The effect of the oral contraceptive (OC) on haematological indices was analysed but not found to be significant. The haemoglobin concentrations were lower than normal laboratory reference values for White subjects in 12.5% of Indian, 16.5% of Black and 4.3% of Oriental control groups respectively. All the White control group were within the normal range. These findings were considered in relation to age, weight, pregnancies, smoking, alcohol consumption, nutritional status, and disorders of haemoglobin synthesis. A deficient iron intake accounted for the high incidence of low haemoglobin in the Indian group in whom low transferrin saturation and serum ferritin were observed. With the possible exception of inherited disorders of haemoglobin synthesis, none of the factors we considered could account for the low haemoglobins found in the Black group. Separate reference values for haematological indices in different ethnic populations are considered.     

Effects of chronic aluminum administration on blood and liver iron-related parameters in mice

In this study, the effects of chronically administered aluminum on iron metabolism-related parameters of liver and blood of mice were investigated. An additional purpose to determine how chronic aluminum administration together with vitamin E as an antioxidant to mice changed the parameters related to iron metabolism. For these purposes, we used 21 adult female Balb-c mice in this study. The animals were divided into three groups: one group with aluminum administered chronically, another group with aluminum plus vitamin E administered chronically, and the control group. Serum levels of hemoglobin, ferritin, iron, transferrin, hematocrit, total iron binding capacity (TIBC), as well as percentage of transferrin saturation were determined in all groups. In addition, the liver tissue levels of ferritin and iron were analyzed. Hemoglobin and hematocrit levels of the aluminum group and aluminum plus vitamin E group were significantly decreased compared to the control. In conclusion, no changes occurred in the serum iron related parameters although Al induced anemia in mice when Al administered chronically. There was an increase in the levels of liver iron and ferritin with Al, but Vit E had no effect on the changes of all blood and liver parameters caused by Al.     

Iron metabolism in boys involved in intensive physical training

The purpose of the present study was to compare some haematological and iron-related parameters of prepubertal boys (10-12 years old) involved in intensive physical training program in preparation for the national championship with nontrained age-matched subjects. For this purpose, iron stores, haemoglobin, ferritin and serum transferrin receptor concentrations were taken into account. The athletes' dietary intakes were similar to the respective intakes in the control group. Mean ferritin concentration was similar in investigated groups of boys at the start of the study, but significant changes between those groups occurred during the 8 months of study. Compared with the control group, the trained ones have shown significantly higher serum transferrin receptor concentration during the competition period of the training season, just when they reached maximum performance capacity. Similarly, significant difference in total body iron, estimated as the sum of the individual's red blood cells iron and iron stores, between investigated groups occurred only during the competition period. The main finding of this study is that the endurance training in boys brings about significant decrease in serum ferritin, as well as iron stores in the body. Haematological parameters and iron status of trained children revealed latent anaemia (15%) or even manifest anaemia (9%). These findings indicate high prevalence of nonanaemic iron deficiency in young athletes and bear relationship to swimming training.     

Serum ferritin levels and transferrin saturation in men with prostate cancer

Elevated body iron stores (serum ferritin >300 microg/L, transferrin saturation TS >50%) are associated with increased risk of liver and lung cancers. To determine whether such association also exists for prostate cancer (PC), we measured serum ferritin, serum iron, total iron-binding capacity (TIBC), and TS in serum samples from 34 men with newly diagnosed, untreated PC and 84 healthy men, ranging in age from 49-78 years. In contrast with other malignancies, men with PC had significantly lower mean concentrations of serum ferritin (156 microg/L) and TS (24.35%) than those without PC (ferritin, 245 microg/L; TS, 31.98%) (p<0.05). The 95% confidence intervals for ferritin were 109-203 microg/L and 205-286 microg/L, and those for TS were 20.29-28.4% and 28.35-35.61% for men with and without PC, respectively. Significant differences were observed between both groups in the distribution of serum ferritin (<100, 101-300, >300 microg/L) and TS (<16, 16-50, >50%) (p<0.05). A lower percentage of cases than of controls had serum ferritin (17.6% versus 29.8%) and TS (5.9% versus 14.7%) above normal. These differences persisted when the analysis was limited to African-American men (31 cases and 52 controls). Data suggest that elevated body iron stores are less common in men with PC compared to those without PC.     

Serum ferritin as a measure of iron stores in the college girls

The average daily iron consumption of the college girls was 48 per cent of the recommended dietary allowances of ICMR (1990). The Hb level was below the normal value. The values of serum iron, transferrin saturation (TS) and unsaturated iron bearing capacity (UIBC) were in the normal range but near the lower margin. The TIBC was above the normal range. The serum ferritin values showed very poor iron stores. A highly significant (p < 0.01) correlation was observed between Hb, serum iron and TS with serum ferritin. There is a superiority of ferritin over other blood parameters as it indicates the liver iron stores, hence, a better predictor of iron deficiency status.     

Iron state in alpha and beta thalassaemia trait.

The iron state was examined in two groups of pregnant women who were carriers of alpha and beta thalassaemia genes. In both groups the haematological expression of the disease--namely, haemoglobin and mean cell haemoglobin concentrations--was nearly identical. In patients with alpha thalassaemia the ferritin concentrations and percentage of ferritin deficiency was the same as in normal pregnant patients, whereas in those with beta thalassaemia the ferritin concentrations were usually much higher and iron deficiency four times less common. This variance appears to be explained by different degrees of extravascular or intravascular haemolysis between the two thalassaemias as assessed by the activities of serum alpha hydroxybutyrate dehydrogenase.     

Clinical utility of serum tests for iron deficiency in hospitalized patients

Serum iron and ferritin measurements lack the requisite sensitivity and/or specificity to accurately diagnose iron deficiency. To determine their utility in hospitalized patients, the authors compared the results of these tests with the presence of stainable iron in bone marrow aspirates of 301 patients. Forty (13.3%) had absent marrow iron. The serum diagnosis of iron deficiency was accepted on the basis of the following: iron less than 11 mumol/L, total iron-binding capacity (TIBC) greater than 45 mumol/L, transferrin saturation (%Sat) less than 0.20, and ferritin less than 13 micrograms/L for females and less than 25 micrograms/L for males. Using these criteria, iron deficiency was correctly diagnosed by serum iron in 41%, TIBC in 84%, %Sat in 50%, and ferritin in 90% of the patients. The serum ferritin is clearly the only useful serum test for diagnosing iron deficiency in hospitalized patients but is limited by a low sensitivity. The bone marrow examination is the most sensitive test for diagnosing iron deficiency in hospitalized patients.     

Transferrin and ferritin response to bacterial infection: The role of the liver and brain in fish

Iron is essential for growth and survival, but it is also toxic when in excess. Thus, there is a tight regulation of iron that is accomplished by the interaction of several genes including the iron transporter transferrin and iron storage protein ferritin. These genes are also known to be involved in response to infection. The aim of this study was to understand the role of transferrin and ferritin in infection and iron metabolism in fish. Thus, sea bass transferrin and ferritin H cDNAs were isolated from liver, cloned and characterized. Transferrin constitutive expression was found to be highest in the liver, but also with significant expression in the brain, particularly in the highly vascularized region connecting the inferior lobe of the hypothalamus and the saccus vasculosus. Ferritin, on the other hand, was expressed in all tested organs, but also significantly higher in the liver. Fish were subjected to either experimental bacterial infection or iron modulation and transferrin and ferritin mRNA expression levels were analyzed, along with several iron regulatory parameters. Transferrin expression was found to decrease in the liver and increase in the brain in response to infection and to increase in the liver in iron deficiency. Ferritin expression was found to inversely reflect transferrin in the liver, increasing in infection and iron overload and decreasing in iron deficiency, whereas in the brain, ferritin expression was also increased in infection. These findings demonstrate the evolutionary conservation of transferrin and ferritin dual functions in vertebrates, being involved in both the immune response and iron metabolism.     

Role of non-transferrin bound iron in iron overload and liver dysfunction in long term survivors of acute leukaemia and bone marrow transplantation.

AIMS: To determine whether nontransferrin bound iron is present in the serum of long term survivors of acute leukaemia and bone marrow transplantation who have liver dysfunction as indicated by consistently raised serum aspartate aminotransferase (AST) activities. METHODS: Thirty eight patients, who were at least three years from the end of treatment, were studied. Serum samples were analysed for hepatitis C, hepatitis B, AST, ferritin, and non-transferrin bound iron. A bleomycin based assay was used to detect non-transferrin bound iron. Patient and blood bank records were examined to determine the number of units of transfused blood received by each patient. RESULTS: Ten patients had consistently raised serum AST activities. Of these, two had evidence of hepatitis C infection, one had chronic hepatitis B infection and one had chronic graft versus host disease affecting the liver. None of these four patients had detectable non-transferrin bound iron. The remaining six patients had no obvious reason for raised AST activities, but four had non-transferrin bound iron detectable in their serum as compared with only two out of 28 patients with normal AST activities. Patients with abnormal AST activities had higher serum ferritin concentrations than those with normal AST, though serum ferritin was raised in 21 of 28 patients without liver dysfunction. CONCLUSION: Non-transferrin bound iron may be found in this group of patients, suggesting that iron overload is the cause of the observed liver dysfunction. Non-transferrin bound iron may also be a more specific indicator of iron overload than the serum ferritin concentrations.     

Difference albumin-transferrin interest in the iron deficiency detection in a cohort of 1288 schoolchildren in the district of Tunis

Iron deficiency (ID) is the most common nutritional deficiency worldwide especially among young children, women in pregnancy and breastfeeding. This study was undertaken to assess the prevalence of ID in 1288 pupil ranging in age from 11 to 14 years. Haemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular Hb (MCH), serum iron (Fe) serum transferrin (Trf), serum ferritin (Ft) and an inflammtory proteic profil (IPP) were measured. The IPP combines the analysis of protein variations: protein results are converted in percent of normal values referenced for the technique used. It has been suggested that on the protein profile, an increase in serum transferrin level compared to a normal serum albumin level (DAT: difference albumin-transferrin), appears early in the course of ID. Iron deficiency was defined by a low serum ferritin (< 15 ng/mL) and/or a pathologic DAT (> 28%). Approximately, 33.8% of children had Ft < 15 ng/mL and 12,8% had DAT > 28% while ferritin values were in the normal range. Diagnosis performance (sensitivity, specificity and diagnosis efficacy) of ferritin and DAT were compared to the performance of high serum transferrin receptor (sTfR) values in 2 populations presenting or not a biological inflammation. Only the diagnosis efficacy of DAT was constant in both situations. In conclusion, the serum ferritin concentration is the first indicator of body storage iron identifying ID, however normal or elevated values of ferritin may be difficult to interpret particulary in the presence of inflammation. sTfR and DAT values are thus reliable indicators of ID in such circumstances.     

Iron metabolism and "sports anemia". II. A hematological comparison of elite runners and control subjects

A hematological comparison was performed between 43 middle and long distance male runners and 119 male controls. The hematocrit, serum iron, transferrin saturation and serum ferritin values were significantly lower in the athletes. The amount of bone marrow hemosiderin was also lower in the athletes than in a group of non-athletic men of the same age. Even if these values were clearly lower than in the controls, they were not low enough to indicate iron deficiency. The observations that sideroblast counts in bone marrow smears were normal and that both red cell indices and red cell protoporphyrin were normal strongly support the conclusion that lack of iron had not limitated erythropoiesis or the formation of an optimal red cell mass. Low serum haptoglobin values in most athletes indicated an increased intravascular hemolysis. As the hemoglobin-haptoglobin complex formed is taken up by hepatocytes, this implies that there is a shift in the red cell catabolism in these athletes from the reticuloendothelial system to the hepatocytes. This shift may explain the paradoxical findings of low serum ferritin concentrations and reduced contents of bone marrow hemosiderin. This is consistent with the observed normal erythropoiesis. It was concluded that runners "anemia" is no true anemia and not caused by iron deficiency. "Sports anemia" is thus no indication for routine iron supplementation.     

Studies on the change in the levels of serum ferritin, serum iron and total iron binding capacity caused by aging and sex difference

Sex difference and aging change of serum ferritin concentration in normal subjects were studied with their relations to serum iron concentration, total iron binding capacity (TIBC) and other hematological parameters. The subjects of this study were the stuff of our hospital (113 males and 330 females) and some old patients without having any diseases of internal medicine (11 males and 23 females), 477 in all. Serum ferritin level was 108.0 +/- 57.8 ng/ml in men and 26.4 +/- 22.7 ng/ml in women, which showed the significant difference between the sexes. In terms of the changes in serum ferritin level by aging, serum ferritin level increased with age from twenties to fifties in the men. On the other hand, it remained low in the women to their forties and its changes by aging were not observed, though it abruptly increased in the women after 50 years of age. The low levels of serum ferritin, iron, transferrin saturation (Fe/TIBC) and hemoglobin of red blood cell were often observed in the women aged from 18 to 45, but rarely found in the women after 50 years of age. According to this fact, the low level of serum ferritin in the young women are considered to be related to the menstruation. Significant correlation between serum ferritin and serum iron or transferrin saturation was shown both in men and women, while that between serum ferritin and hemoglobin of red blood cell was shown only in women.(ABSTRACT TRUNCATED AT 250 WORDS)     

The HLA linked iron loading gene in an Afrikaner population.

The serum ferritin concentration was used as a screening test to identify the presence of iron overload in 599 Afrikaans subjects (300 males and 299 females) living in the South Western Cape, South Africa. Seventeen of the males with concentrations greater than 400 micrograms/l were reevaluated three and five years later. Serum ferritin concentrations were measured again and further diagnostic procedures were carried out. These included an assessment of alcohol intake and measurements of serum gamma glutamyltransferase, the percentage saturation of transferrin, and HLA-A,-B,-C, and -DR loci typing on the subjects as well as their families. Liver biopsies were performed on some affected subjects. Of the original 16 index subjects, four were diagnosed as homozygous for the HLA linked iron loading gene which is responsible for the clinical disease idiopathic haemochromatosis. Six appeared to be heterozygotes, three were heterozygotes who were also abusing alcohol, and two did not fit into any of the diagnostic groups. The calculated gene frequency was 0.082, with an expected heterozygote frequency of 0.148. The fact that no females were identified in the study suggested that the diagnostic criteria for homozygosity (serum ferritin greater than 400 micrograms/l and % saturation greater than 60%) were set too high. The data were therefore recalculated for the 300 males; when this was done the gene frequency was 0.115 and the heterozygote frequency 0.024. Two subjects were diagnosed as homozygotes in the study of family members and 37 as heterozygotes (33 definite and four probable). Both the homozygotes and nine of the heterozygotes showed mild to moderate disturbances of iron metabolism. There was considerable overlap between the phenotype expression in these nine heterozygotes and the homozygotes, probably as a result of setting the threshold for the serum ferritin concentrations at the relatively high value of 400 microgram/ml. By doing this a small subset of heterozygotes with biochemical abnormalities was identified. The results of the present pilot study suggest a high frequency of the HLA linked iron loading gene in the Afrikaner population of South Western Cape.     

Serum markers of stored body iron are not appropriate markers of health effects of iron: a focus on serum ferritin

Experimental studies have consistently shown that iron is a critical catalyst in generating oxygen free radicals via Fenton chemistry. Nevertheless, epidemiologic studies conflict on the association between stored body iron markers and disease outcomes, including coronary heart disease. We hypothesize that stored body iron markers common in epidemiologic studies, such as serum ferritin, transferrin saturation, iron, or iron-binding capacity, are inappropriate to investigate harmful health effects related to iron overload. Oxygen free radicals are produced only by free iron, but stored body iron markers reflect iron bound to ferritin or transferrin, which are produced to sequester catalytically active free iron. Moreover, increased serum ferritin may occur as a defense mechanism in response to oxidative stress; such increase might eventually minimize oxidative stress and consequent pathology due to free iron. Therefore, though highly correlated with stored body iron, a measure of bound iron will fail to identify any harmful effect, unless it is also a marker of free iron. It is generally believed that free iron rarely exists, except in iron-overload with 100% transferrin saturation. However, some recent studies find non-transferrin bound iron (NTBI) or the intracellular labile iron pool (LIP) in the presence of triggers disturbing iron homeostasis, such as alcohol consumption. In contrast to the tight bond in ferritin or transferrin, free iron is more likely to dissociate from a looser bond. Therefore research on the relation of iron with disease outcomes should investigate NTBI or the intracellular LIP. Any positive influence of iron on coronary heart and other diseases might be observable only when a trigger is present. These factors may explain why there have been conflicting results between serum markers of stored body iron and disease outcomes in epidemiological studies.     

Impact of hemochromatosis screening in patients with indeterminate results: the hemochromatosis and iron overload screening study.

PURPOSE: Assess the quality of life impact of receiving indeterminate test results for hemochromatosis, a disorder involving HFE genetic mutations and/or elevated serum transferrin saturation and ferritin. METHODS: The study sample was from the Hemochromatosis and Iron Overload Screening Study, a large observational study of hemochromatosis among primary care patients in the US and Canada using HFE genotype and serum transferrin saturation and ferritin screening. Study subjects included 2,304 patients found with hemochromatosis risk of uncertain clinical significance. Assessed was SF-36 general health and emotional well-being before screening and six weeks after participants received their test results. Health worries were assessed after screening. RESULTS: Of the study subjects, 1,268 participants (51.5%) completed both assessments. Compared to normal controls, those with HFE mutations or elevated serum transferrin saturation and ferritin levels of uncertain significance were more likely to report diminished general health and mental well-being, and more health worries. These effects were associated with participants' belief of having tested positive for hemochromatosis or iron overload. CONCLUSION: Notification of indeterminate results from screening may be associated with mild negative effects on well-being, and might be a potential participant risk in screening programs for disorders with uncertain genotype-phenotype.     

Iron metabolism and "sports anemia". I. A study of several iron parameters in elite runners with differences in iron status

Several reports have suggested that iron deficiency might explain "sports anemia" especially in long distance runners. The present study was made to further study the iron metabolism in runners as the proposed cause of "sports anemia" is abstruse considering the good iron nutrition in these athletes. Based on a screening of 43 elite male runners, using bone marrow hemosiderin, serum ferritin and transferrin saturation, two groups of subjects were selected for a very extensive study on iron metabolism. In group 1 (n = 5) iron depletion was suggested in at least one of the screening studies. In group 2 (n = 7) at least one test strongly indicated good iron repletion. This experimental design was chosen to obtain two groups with similar body composition and exercise load but different iron metabolism. The studies comprised determinations of red cell and plasma volumes, plasma iron turnover and red cell incorporation of radioiron, red cell indices, plasma iron and transferrin, red cell protoporphyrin, serum ferritin, serum haptoglobin, urinary iron losses, iron absorption, bone marrow hemosiderin, dietary intake of energy and nutrients and a Desferal test. Pooling the results together it was obvious that none of the subjects were truly iron-deficient. A few occasional findings suggesting low iron stores cannot be satisfactorily explained and indicate that further studies are needed.