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Background: Serum transferrin receptor concentrations indicate both erythropoietic activity and the deficit of functional iron in the erythron. In contrast with serum ferritin concentrations, serum transferrin receptor concentrations are not or are only marginally influenced by the inflammatory response to infection. Objective: We assessed iron status and examined the relation between serum transferrin receptor concentrations and malaria in children aged 2-36 mo who were asymptomatic for malaria. Design: This was a community-based cluster survey (n = 318). Results: Prevalences of malaria, anemia (hemoglobin concentration < 110 g/L), iron deficiency (serum ferritin concentration < 12 [micro]g/L), and iron deficiency anemia were 18%, 69%, 53%, and 46%, respectively. Malaria was associated with lower mean hemoglobin concentrations (92.7 compared with 104.1 g/L; P = 0.0001) and higher geometric mean serum concentrations of transferrin receptor (11.4 compared with 7.8 mg/L; P = 0.005), ferritin (21.6 compared with 11.9 [micro]g/L; P = 0.05), and C-reactive protein (12.5 compared with 6.8 mg/L; P = 0.004). There was no evidence for an association between serum concentrations of C-reactive protein and transferrin receptor. Children with malaria had higher serum transferrin receptor concentrations than expected for the degree of anemia, even after adjustment for inflammation indicated by serum C-reactive protein concentration quartiles (P = 0.02). Conclusions: Our findings are consistent with the notion that malaria-induced hemolysis is accompanied by increased erythropoiesis. Serum transferrin receptor concentration is not useful for detecting iron deficiency in individuals with malaria. Individuals with high concentrations of serum C-reactive protein or similar acute phase reactants should be excluded from analysis if serum ferritin concentrations < 12 [micro]g/L are to be used to measure iron deficiency in malaria-endemic areas. Am J Clin Nutr 2001;74:767-75. KEY WORDS Iron deficiency, anemia, ferritin, transferrin receptors, C-reactive protein, falciparum malaria, helminthiasis, preschool children, Kenya, community survey

We studied serum transferrin and ferritin concentrations in relation to individual body growth, stage of puberty, blood hemoglobin, and red blood cell iron (RBCI) in 60 prepubertal or early pubertal boys at 3-mo intervals for 18 mo. One-third of the boys had increased serum transferrin concentrations and almost all had decreased ferritin concentrations during the follow-up. No change in mean transferrin was observed but the individual 18-mo increments in transferrin correlated positively with the increments in hemoglobin (r = 0.55, P < 0.001) and in estimated RBCI (r = 0.31, P = 0.02). Serum transferrin remained stable at different genital stages, but ferritin was lower in the pubertal than in the prepubertal boys. Transferrin concentrations at 18 mo correlated positively with the preceding weight velocities. The rise in transferrin did not lead to an increase in iron-deficiency anemia. In contrast, transferrin rose in boys whose hemoglobin increased. In pubertal boys with relatively ample iron status, serum transferrin may be an indicator of increased availability of iron for erythropoiesis. The declining ferritin concentration indicates that part of the extra iron is mobilized through redistribution from stores to red blood cell mass and is generally associated with greatly increasing absorption. Thus, the pubertal changes in transferrin and ferritin are not necessarily indications of iron deficiency.

To determine whether normal physiologic changes associated with hormone fluctuations over the menstrual cycle affect concentrations of iron-status indicators, we examined data from 1712 women aged 18-44 y from the Second National Health and Nutrition Examination Survey (NHANES II) after adjusting for potential confounders. Adjusted mean values of hemoglobin (Hb), transferrin saturation (TS), and serum ferritin (SF) were lowest for women whose blood was drawn during menses and highest for women examined in luteal or late luteal phase of the menstrual cycle (Hb = 130 vs 133 g/L; TS = 21.2% vs 24.8%, P < 0.01 for both; and SF = 17.2 vs 24.0 [mu]g/L, P < 0.05). The prevalence estimate of impaired iron status was significantly higher for women whose blood was drawn during the menstrual phase than for women whose blood was drawn during the luteal and late luteal phases. Our findings suggest that the phases of the menstrual cycle affect the concentration or values of iron-status indicators. These cyclic variations in indicators of iron status are a potential source of error when iron status is assessed in large population surveys that include women of reproductive age.

The iron status of 3228 subjects from the nutrition survey Proyecto Venezuela was studied. The sample included children from 1 to 16 y of age grouped by age and sex. Values for three indicators of iron status were compared: hemoglobin concentration, serum ferritin concentration, and percentage saturation of serum transferrin. In all groups there was a strong overlap in the hemoglobin concentration distribution curves for non-iron-deficient and iron-deficient subjects classified as such according to the other two indexes. The prevalence of iron deficiency ranged from 35% in 1-3 y olds to 10% in adolescent males, the values being almost identical in the nonanemic group compared with the total population. In the different groups, 80-97% of the subjects with abnormal values of at least one of these two indexes were not anemic. The difficulties involved in establishing a state of iron deficiency according to these indexes are discussed.

Day-to-day variability in biochemical indicators of iron status in well-hydrated and healthy women 70-79 y old (n = 10) was determined. Venous blood was collected on 4 nonconsecutive days during a 2-wk period. Analytical ([delta.sup.2.sub.rep]) and biological ([delta.sup.2.sub.fd]) variance components were computed based on a previously established scheme in younger adults. These two variance components were summed to obtain the total day-to-day variability ([delta.sup.2.sub.fd]). Our results indicate that biological variation contributed most to the intraindividual variation. We calculated that sampling once for most iron indexes and twice for plasma transferrin receptors in elderly individuals is adequate to accurately determine these indexes whereas serum iron and transferrin saturation, indexes with high [CV.sub.fd], require seven and eight measurements, respectively. These data, compared with previously published data in younger adults, demonstrate that aging is associated with a decreased variation in some indexes of iron status such as serum ferritin. Am J Clin Nutr 1993:57:414-9

During pregnancy the amount of iron required by the body increases, and iron deficiency anemia is common during pregnancy. It has been reported that even mild anemia can increase the risk of premature delivery and perinatal mortality. Diagnosing anemia during pregnancy can be difficult because during pregnancy the plasma volume (amount of fluid in the blood) increases. Transferrin is a protein that transports iron in the blood. It binds to a protein in cell membranes (called the transferrin receptor) and it transfers the iron into the cell. Recently, it was reported that during anemia, when iron supply is low, the amount of transferrin receptor in the blood increases. Therefore, a study was performed to determine if measuring the amount of transferrin receptor in the blood is a good method for diagnosing anemia during pregnancy. The study included 176 women in the third trimester of pregnancy. The amount of transferrin receptor in the blood was measured in each subject, and iron deficiency was diagnosed by measuring blood levels of hemoglobin (a red blood cell protein that contains iron), ferritin (the storage form of iron) and erythrocyte protoporphyrin (an iron-containing pigment in red blood cells). Forty-four percent of the women had depleted iron stores, and 13 were diagnosed as having iron deficiency anemia. Eighty-five percent of the women with iron deficiency anemia had abnormally high levels of transferrin receptor in their blood. It is concluded that blood transferrin receptor levels are a sensitive index of iron deficiency in pregnancy. (Consumer Summary produced by Reliance Medical Information, Inc.)

Background: The serum transferrin receptor (TfR) and the ratio of TfR to serum ferritin (TfR:SF) have been shown to be useful as early indicators of iron deficiency. Objective: The objective of this study was to evaluate the performance of TfR and TfR:SF in the assessment of iron deficiency in infants and to analyze age-related changes in both variables. Design: A total of 716 blood samples obtained from 515 healthy infants aged 8-15 mo were studied. Results: In 144 samples in which all other laboratory indicators of iron status were within the reference range, the median and 95% CI for TfR and TfR:SF were 8.5 mg/L (95% CI: 5.9, 13.5) and 497 (95% CI: 134, 975), respectively. TfR and TfR:SF were significantly correlated with the other laboratory indicators of iron status. Furthermore, as the severity of iron deficiency progressed, there was a gradual increase in mean TfR concentration (P [is less than] 0.00001; analysis of variance). The sensitivity of TfR [is greater than] 13.5 mg/L and TfR:SF [is greater than] 975 in the diagnosis of iron deficiency was 23.6% and 68.4%, respectively. The specificity was 98.3% and 63.3% for TfR and TfR:SF, respectively. The sensitivity and specificity of SF [is less than] 10 [micro]g/L were 63.7% and 60.8%, respectively. Receiver operator characteristic analysis showed that TfR and TfR:SF were more accurate than was SF alone in the diagnosis of iron deficiency. Conclusions: TfR and TfR:SF showed age-related changes; TfR and TfR:SF appear to be better diagnostic tests for iron deficiency in infants than SF. Am J Clin Nutr 2000;72:1191-5. KEY WORDS Transferrin receptor, serum ferritin, ratio of transferrin receptor to ferritin, iron deficiency, infants

Approximately 15-20% of type 1 diabetic patients show parietal cell antibodies (PCA). PCA+ subjects may be at increased risk for iron deficiency anaemia, a manifestation of gastric autoimmunity. Soluble transferrin [...]