Prediction of iron absorption based on iron status of female blood donors

Dietary factors associated with the risk of high iron stores in the elderly Framingham Heart Study cohort

BACKGROUND

High body iron stores may increase the risk of several chronic diseases. Whether dietary factors contribute to the risk of high iron stores is unknown.

OBJECTIVE

We assessed the relation between dietary factors and the risk of high iron stores in the elderly Framingham Heart Study cohort.

DESIGN

We examined the relation between the usual intake of dietary factors (food-frequency questionnaire) and the risk of high iron stores (serum ferritin >300 and 200 micro g/L in men and women, respectively) in 614 subjects aged 68-93 y.

RESULTS

The risk of high iron stores was significantly higher 1) in subjects who took > or =30 mg supplemental Fe/d than in nonusers [odds ratio (OR): 4.32; 95% CI: 1.63, 11.47], 2) in subjects who consumed >21 servings of fruit/wk than in those who consumed < or =14 servings/wk (OR: 2.88; 95% CI: 1.26, 6.61), and 3) in subjects who consumed >4 but <7 or > or=7 servings of red meat/wk than in those who consumed < or =4 servings/wk (ORs: 2.94 and 3.61, respectively; 95% CIs: 1.33, 6.47 and 1.57, 8.27, respectively). Whole-grain intake (>7 servings/wk) was inversely associated (OR: 0.23; 95% CI: 0.07, 0.75).

CONCLUSIONS

Among elders, intakes of highly bioavailable forms of iron (supplemental iron and red meat) and of fruit, a dietary source of an enhancer of nonheme-iron absorption (vitamin C), promote high iron stores, whereas foods containing phytate (whole grains) decrease these stores. Individual dietary patterns may be important modulators of high iron stores.

Aspirin intake and the use of serum ferritin as a measure of iron status

BACKGROUND

Atherosclerosis, a primary cause of myocardial infarction (MI), is an inflammatory disease. Aspirin use lowers risk of MI, probably through antithrombotic and antiinflammatory effects. Because serum ferritin (SF) can be elevated spuriously by inflammation, reported associations between elevated SF, used as an indicator of iron stores, and heart disease could be confounded by occult inflammation and aspirin use if they affect SF independently of iron status.

OBJECTIVE

We tested the hypothesis that aspirin use is associated with reduced SF.

DESIGN

We used analysis of covariance to investigate the relation between SF and categories of aspirin use in 913 elderly participants aged 67-96 y in the Framingham Heart Study.

RESULTS

After adjustment for sex, age, body mass index, smoking, alcohol use, concentrations of C-reactive protein and liver enzymes, white blood cell count, and use of nonaspirin nonsteroidal antiinflammatory drugs and other medications, subjects who took >7 aspirins/wk had a significantly lower (by 25%) geometric mean SF than did nonusers, who took <1 aspirin/wk (71 compared with 95 microg/L, respectively; P for trend = 0.004). This effect of aspirin on SF was more marked in diseased subjects than in healthy subjects (mean SF was 50% lower compared with 21% lower, respectively).

CONCLUSIONS

Aspirin use is associated with lower SF. We suggest this effect results from possible increased occult blood loss and a cytokine-mediated effect on SF in subjects with inflammation, infection, or liver disease. The relations between aspirin, inflammation, and SF may confound epidemiologic associations between elevated SF, as an indicator of iron stores, and heart disease risk.

Nutrient intakes and iron status of elderly men and women

Nutrient intake including iron and iron status indicators were investigated in 96 elderly subjects. Subjects were divided into 6 groups based on the sex and age. Each subject completed a 24-h diet recall and semi-quantitative food frequency questionnaire. Iron status indicators were measured. Body iron stores were calculated. The mean iron intake was higher than the current Taiwan Recommended Daily Nutrient Allowance of 10 mg in all groups. However, iron intake did not correlate with iron status indicators in any groups. Body iron stores significantly positively correlated with plasma ferritin (p < 0.05). One man in 65-69 y group, 2 men in 70-74 y group, 3 women in 65-69 y group, and 2 women in 70-74 y group were identified iron deficiency anemia. Elderly subjects had sufficient iron intakes, but iron deficiency still occurred in the elderly.

Iron status of the free-living, elderly Framingham Heart Study cohort: an iron-replete population with a high prevalence of elevated iron stores

BACKGROUND

Although iron deficiency occurs commonly in vulnerable groups of women of reproductive age, infants, and children, less is known about the iron nutriture of the elderly.

OBJECTIVE

Our objective was to evaluate the iron status of a noninstitutionalized, elderly US population, with a particular focus on 2 concerns unique to the elderly: 1) potential confounding effects of chronic disease on iron measures and 2) increased occurrence of elevated iron stores.

DESIGN

Multiple iron measures, including serum ferritin (SF), transferrin saturation, mean cell volume, and hemoglobin, were used to evaluate the prevalence of iron deficiency (ID), iron deficiency anemia (IDA), and other measures of iron nutriture in 1016 elderly white Americans aged 67-96 y from the Framingham Heart Study. "Diseased" subjects were defined as those with possible pathologically altered iron measures due to inflammation, infection, elevated liver enzymes, hereditary hemochromatosis, or cancer. The effect of altered iron status on various prevalence estimates was assessed.

RESULTS

The elderly subjects had a low prevalence of ID (2.7%), IDA (1.2%), and depleted iron stores (3%; SF < 12 microg/L). In contrast, 12.9% had elevated iron stores (SF > 300 microg/L in men and SF > 200 microg/L in women), of which only 1% was attributable to chronic disease. The prevalence of ID, IDA, and depleted iron stores was unaffected by the presence of chronic disease.

CONCLUSIONS

The Framingham Heart Study cohort is an iron-replete elderly population with a high prevalence of elevated iron stores in contrast with a low prevalence of iron deficiency, with insignificant effects of chronic disease on these iron status estimates. The likely liability in iron nutriture in free-living, elderly white Americans eating a Western diet is high iron stores, not iron deficiency.

Population-based screening for hemochromatosis using phenotypic and DNA testing among employees of health maintenance organizations in Springfield, Missouri

BACKGROUND

Hemochromatosis reportedly affects 3 to 8 persons per 1,000 and is associated with an elevated risk of morbidity and mortality. We sought to ascertain its prevalence in a community and to assess the association between phenotype and genotype.

METHODS

All health maintenance organization employees were invited to participate in hemochromatosis screening using a repeated elevation of the transferrin saturation test as the case definition (> or = 50% in women and > or = 60% in men with no other cause). Iron overload from hemochromatosis was defined as serum ferritin concentration > or = 95th percentile and mobilizable iron > or = 99th percentile for age and sex, or hepatic iron index > or = 1.9. The HFE gene was analyzed for mutations.

RESULTS

Participation among employees was 28% (1,653 of 6,000); 83% were women. The prevalence of hemochromatosis was 8 per 1,000 (13 of 1,653), and the prevalence of iron overload from hemochromatosis was 4 per 1,000 (5 of 1,653). Compared with those who had no HFE mutation, the relative risk (RR) for hemochromatosis was greatest for C282Y homozygotes (RR = 147), compound heterozygotes (RR = 19), and H63D homozygotes (RR = 9). Overall, 38% of participants had at least one HFE mutation. Screening based on an initial elevated transferrin saturation test had the best sensitivity, whereas DNA testing offered the best specificity and predictive value positive for iron overload disease.

CONCLUSIONS

In this population, we found a greater than expected prevalence of hemochromatosis and demonstrated a clear association with the HFE genotype. Promotion of screening is complicated by controversies in case definition and the large number of persons who will be detected before they have clinically significant iron loading, in whom the risk of clinical disease is unknown. Larger screening studies in more diverse populations are necessary to characterize the burden of disease and to follow those at risk (based on HFE or iron status measures) to establish the natural history of hemochromatosis.

Iron stores in professional athletes throughout the sports season

Sports anemia provoked by iron deficiency develops slowly and although the existence or reality of this condition is under discussion, the ferritin levels tend to reduce with sports practice. This paper analyzes the variations of iron metabolism, including the organism stores of this metal throughout a sports season in a group of professional sportsmen (soccer players) belonging to a team of the Spanish First Division. For the determination of the iron stores, a computer program has been developed that takes into account the ferritin concentrations, hemoglobin, and saturation of transferrin. The results show that at the end of the season, when the ferric supplementation, which had been performed at the other moments of analysis, was no longer administered the iron stores reduced significantly, as well as the serum ferritin concentration, without such decreases being considered as a prelatent (grade I) anemia.

Impact of HLA-H mutations on iron stores in healthy elderly men and women

The DNA of 287 healthy white elderly volunteers in the New Mexico Aging Process Study, between 63 and 91 years of age, was examined for mutations of the HLA-H gene at nt 845 and nt 187. None were found to be homozygous for the 845A mutation and there were no gender differences in the percentage of the various mutations. The frequency of the 845A mutation was 0.061 resulting in a carrier frequency of 12.2%. The frequency of the 187G mutation was 0.136 resulting in a carrier frequency of 19.9% for a single mutation; 2.4% were compound heterozygous, 834A/187G and 2.4% were homozygous for the 187G mutation. After excluding 5 men and 4 women with microcytic or macrocytic anemia, mean percent transferrin saturation (PSAT) and iron stores, as estimated from serum ferritin concentrations, were calculated for each mutation. Estimated iron stores were normally distributed (range approximately 50 to 1,550 mg) with men (n=111) having significantly higher mean estimated iron stores than women (n=167), 826 +/- 318 and 753 +/- 287 mg, respectively. More men, 15 of 28, (54%) with estimated iron stores in the upper quartile, >/= 1,050 mg, had a HLA-H mutation compared to 25 of 83 (30%) who had a mutation and whose estimated iron stores were < ,050 mg, P<0.05. Seven were heterozygous for the 845A mutation with mean estimated iron stores of 1,300 +/- 127 mg, 7 were heterozygous for the 187G mutation with mean estimated iron stores of 1,439 mg. Similar differences were not noted in women. Even though the potential role of the 187G mutation in the phenotypic expression of HH is less certain than the 845A mutation, the increase in PSAT seen in men with the 187G mutation and the equal distribution of 845A and 187G mutations seen with iron stores >/= 1,050 mg lends support for the involvement of the 187G mutation, or a linked mutation, in iron metabolism. We concluded that men having either a single chromosomal 845A and/or 187G mutation results in higher PSAT's and estimated iron stores than if no HLA-H mutation were present.

Iron-deficiency anaemia

Iron-deficiency anaemia (IDA) is a common clinical problem throughout the world and an enormous public health problem in developing countries. The cornerstone of the laboratory identification of IDA is a low haemoglobin and serum ferritin concentration although a normal serum ferritin does exclude IDA. When the serum ferritin is normal in an anaemic patient with iron-deficient erythropoiesis, it is common practise to perform a bone marrow examination to diagnose IDA. The recent introduction of serum transferrin receptor measurements is a useful alternative for distinguishing IDA from the anaemia of chronic disease because the serum receptor concentration is usually elevated in patients with IDA but normal in patients with anaemia due to inflammation or neoplasia. It is helpful for the clinican to be aware of the causes of physiological IDA. The most important are increased rate of body growth, excessive menstrual blood loss, pregnancy, regular blood donation, intensive endurance training, chronic aspirin use and a vegetarian diet. Without these, a careful search for unsuspected gastrointestinal blood loss must be made and even when the suspicion of physiological IDA is high, it is prudent to screen for fecal occult blood. In most patients, IDA responds promptly to oral iron therapy. Patients who experience troublesome side-effects with oral iron might benefit from a gastric delivery system for oral iron which eliminates nausea and vomiting and improves iron absorption when given with food.(ABSTRACT TRUNCATED AT 250 WORDS)