The measurement of reticuloendothelial iron release using iron-dextran

Current status of pharmacologic therapies in patient blood management

Patient blood management(1,2) incorporates patient-centered, evidence-based medical and surgical approaches to improve patient outcomes by relying on the patient's own (autologous) blood rather than allogeneic blood. Particular attention is paid to preemptive measures such as anemia management. The emphasis on the approaches being "patient-centered" is to distinguish them from previous approaches in transfusion medicine, which have been "product-centered" and focused on blood risks, costs, and inventory concerns rather than on patient outcomes. Patient blood management(3) structures its goals by avoiding blood transfusion(4) with effective use of alternatives to allogeneic blood transfusion.(5) These alternatives include autologous blood procurement, preoperative autologous blood donation, acute normovolemic hemodilution, and intra/postoperative red blood cell (RBC) salvage and reinfusion. Reviewed here are the available pharmacologic tools for anemia and blood management: erythropoiesis-stimulating agents (ESAs), iron therapy, hemostatic agents, and potentially, artificial oxygen carriers.

Detection, evaluation, and management of iron-restricted erythropoiesis

Progress in our understanding of iron-restricted erythropoiesis has been made possible by important advances in defining the molecular mechanisms of iron homeostasis. The detection and diagnostic classification of iron-restricted erythropoiesis can be a challenging process for the clinician. Newer assays for markers of inflammation may allow more targeted management of the anemia in these conditions. The availability of new intravenous iron preparations provides new options for the treatment of iron-restricted erythropoiesis. This review summarizes recent advances regarding the detection, evaluation, and management of iron-restricted erythropoiesis.

Iron sequestration and anemia of inflammation

Anemia of chronic disease, also called anemia of inflammation, is characterized by hypoferremia due to iron sequestration that eventually results in iron-restricted erythropoiesis. During the last decade, the molecular mechanisms of iron sequestration have been found to center on cytokine-stimulated overproduction of the iron-regulatory hormone hepcidin. The inflammatory cytokine interleukin-6 (IL-6) is a particularly prominent inducer of hepcidin, but other cytokines are likely to contribute as well. Hepcidin excess causes the endocytosis and proteolysis of the sole known cellular iron exporter, ferroportin, trapping iron in macrophages and iron-absorbing enterocytes. The supply of iron to hemoglobin synthesis becomes limiting, eventually resulting in anemia. Depending on the details of the underlying disease, other inflammation-related mechanisms may also contribute to anemia.

Iron therapy in patients undergoing maintenance hemodialysis

Twelve patients in maintenance hemodialysis, receiving long-term oral iron therapy, have been treated with i.v. iron dextran, in order to evaluate the effect on the Hb level. Both Hb and hematocrit were unchanged before and after the iron dextran infusion (p greater than 0.5, p greater than 0.7, respectively). Oral iron therapy is usually sufficient to maintain an adequate iron balance in dialysed patients and should be preferred to parenteral iron in view of the better utilization and absence of side-effects. The indication for parenteral iron should be limited to patients with impaired gastrointestinal iron absorption.

Iron absorption in patients with chronic uremia undergoing regular hemodialysis

Gastrointestinal iron absorption has been measured by whole body counting in 17 patients with chronic uremia undergoin regular hemodialysis. Absorption was expressed as whole body retention 14 days after oral administration of 10 muCi 59Fe together with a carrier dose of 10 mg Fe2+. The percentage incorporation in the total erythrocyte mass of administered 59Fe (erythrocyte incorporation) and absorbed 59Fe (red cell utilization) was estimated as well. Geometric mean iron absorption was 14.3 +/- 2.0 (S.D.)% and significantly higher than the value obtained in a normal control group (p less than 0.03). Geometric mean erythrocyte incorporation was 11.6 +/- 2.3 (S.D.)% and arithmetic mean red cell utilization was 84.4 +/- 6.0 (S.E.M.)%. Neither of these parameters differed from corresponding values in the control group (p greater than 0.1 and p greater than 0.2, respectively). The correlation between iron absorption and erythrocyte incorporation was highly significant (r=0.94, p less than 0.001). Patients on regular hemodialysis are subjected to considerable iron loss which should be treated by iron supplementation; oral iron administration is recommended in view of the adequate gastrointestinal absorption.

Iron absorption and iron status in patients with chronic uremia on regular peritoneal dialysis

Gastrointestinal iron absorption was measured by whole body counting in 18 patients on regular peritoneal dialysis. Ten patients received regular oral iron treatment prior to the study (iron treated group), 8 patients did not receive iron treatment (non-iron treated group). Whole body retention 14 days after oral administration of 10 microCi 59Fe together with a carrier dose of 10 mg Fe2+ was used as an estimate of absorption. The erythrocyte iron incorporation, i.e. the percentage of administered 59Fe incorporated into the total erythrocyte mass, was measured. Geometric mean iron absorption in the non-iron treated groups was 7.4+/-3.3 (S.D.) % and in the iron treated group 2.8+/-2.5% (p less than 0.01). Absorption in the non-iron treated group did not differ significantly from the value in a normal control group (p greater than 0.3). Absorption in the iron treated group was distinctly lower than in the controls (p less than 0.01), due to the high iron supplementation. Several patients in the non-iron treated group had latent or overt iron deficiency, while patients in the iron treated group had satisfactory iron status. The correlation between iron absorption and erythrocyte iron incorporation was highly significant (r=0.95, p less than 0.001). Peritoneal dialysis patients on the whole have a normally functioning iron absorption. However, due to increased iron losses and insufficient dietary iron intake, the maintenance of a satisfactory iron balance implies an adequate oral iron supplementation.

Erythropoietin and iron-restricted erythropoiesis

Twenty five years ago, Finch summarized knowledge gained primarily from studies of normal individuals, patients with hereditary hemolytic anemias, and patients with hemochromatosis [1]. Under conditions of basal erythropoiesis in normal subjects, plasma iron turnover (as an index of marrow erythropoietic response) is little affected, whether transferrin saturation ranges from very low to very high levels. In contrast, the erythropoietic response in individuals with congenital hemolytic anemia, in whom erythropoiesis is chronically raised up to sixfold over basal levels [2], is affected (and limited) by serum iron levels and by transferrin saturation [3]. Patients with hemochromatosis who underwent serial phlebotomy were observed to mount erythropoietic responses of up to eightfold over basal rates, attributed to the maintenance of very high serum iron and transferrin saturation levels in these patients [4], whereas normal individuals were shown to have difficulty providing sufficient iron to support rates of erythropoiesis greater than three times basal rates [5]. These observations led Finch to identify a "relative iron deficiency" state, also known as "functional iron deficiency," which he defined as circumstances in which increased erythron iron requirements exceed the available supply of iron [6]. In another clinical setting, patients undergoing autologous blood donation represent a model for perisurgical blood loss and the erythropoietic response. Insights gained over the last 20 years regarding the relationship between erythropoietin, iron, and erythropoiesis, along with implications for clinical management, will be reviewed.

Molecular pathogenesis of anemia of chronic disease

Most patients suffering from chronic infections, chronic inflammatory diseases, and some malignancies develop a mild to moderate anemia designated anemia of chronic disease or anemia of inflammation. Patients with this anemia have low serum iron, low to normal transferrin, and high to normal serum ferritin concentration. The anemia is caused by increased inflammatory cytokines, especially IL-6, inducing increased production of the iron-regulatory hormone hepcidin by hepatocytes. Hepcidin blocks the release of iron from macrophages, hepatocytes, and enterocytes, causing the characteristic hypoferremia associated with this anemia and iron-deprivation of the developing erythrocytes.

Iron metabolism in the reticuloendothelial system

Comprised mainly of monocytes and tissue macrophages, the reticuloendothelial system (RES) plays two major roles in iron metabolism: it recycles iron from senescent red blood cells and it serves as a large storage depot for excess iron. Although iron recycling by the RES represents the largest pathway of iron efflux in the body, the precise mechanisms involved have remained elusive. However, studies characterizing the function and regulation of Nramp1, DMT1, HFE, FPN1, CD163, and hepcidin are rapidly expanding our knowledge of the molecular aspects of RE iron handling. This review summarizes fundamental physiological and biochemical aspects of iron metabolism in the RES and focuses on how recent studies have advanced our understanding of these areas. Also discussed are novel insights into the molecular mechanisms contributing to the abnormal RE iron metabolism characteristic of hereditary hemochromatosis and the anemia of chronic disease.

Iron sucrose: the oldest iron therapy becomes new

Several parenteral iron preparations are now available. This article focuses on iron sucrose, a hematinic, used more widely than any other for more than five decades, chiefly in Europe and now available in North America. Iron sucrose has an average molecular weight of 34 to 60 kd, and after intravenous (IV) administration, it distributes into a volume equal to that of plasma, with a terminal half-life of 5 to 6 hours. Transferrin and ferritin levels can be measured reliably 48 hours after IV administration of this agent. Iron sucrose carries no "black-box" warning, and a test dose is not required before it is administered. Doses of 100 mg can be administered over several minutes, and larger doses up to 300 mg can be administered within 60 minutes. The efficacy of iron sucrose has been shown in patients with chronic kidney disease (CKD) both before and after the initiation of dialysis therapy. Iron sucrose, like iron gluconate, has been associated with a markedly lower incidence of life-threatening anaphylactoid reactions and may be administered safely to those with previously documented intolerance to iron dextran or iron gluconate. Nonanaphylactoid reactions, including non-life-threatening hypotension, nausea, and exanthema, also are extremely uncommon with iron sucrose. Management of patients with the anemia of CKD mandates that we carefully examine the effectiveness and safety of this oldest of iron preparations and the accumulating present-day data regarding it and contemporaneous agents.

Gender modulates responsiveness to recombinant erythropoietin

Several investigators reported that individuals with diabetes and women on hemodialysis treated with recombinant erythropoietin (EPO) attained lower hematocrits than individuals without diabetes and men. It is unclear whether these observed differences in achieved hematocrits are caused by inherent biological differences in responsiveness to EPO or undetected differences in modifiable factors that affect response to EPO. Also potentially modulating response to EPO is diurnal variation in the bioavailability of serum iron. To address these issues, we studied 309 patients undergoing hemodialysis in two large facilities in New York City. Retrospective data collected monthly for 3 months included patients' hematocrit, dose of EPO, urea reduction ratio (URR), total amount of intravenous iron administered, serum albumin concentration, transferrin saturation, and time of day patient underwent dialysis. The 309 study subjects (165 women, 144 men) included 207 blacks (67%), 74 Hispanics (24%), 23 whites (7%), and 5 Asians (2%) with a mean age of 55.4 +/- 15.6 (SD) years. Despite a greater mean URR (74% +/- 6.4% versus 71% +/- 6%; P = 0.001) and a 39% greater dose of EPO (97 +/- 65 versus 59 +/- 53 U/kg; P = 0.001), women (36% +/- 3.5%) had hematocrits equivalent with men (36.5% +/- 3.7%; P = not significant [NS]). There was no difference in the amount of intravenous iron administered to men (375 +/- 389 mg) and women (377 +/- 413 mg; P = NS). Diabetes mellitus (P = 0.48) did not significantly affect the odds of attaining a hematocrit greater than 33% after adjustment for URR, EPO dose, and amount of intravenous iron administered. The time of day a patient underwent dialysis (P = 0.93) had no effect on their response to EPO. We conclude that gender, but not diabetes status or time of dialysis, modulates response to EPO in hemodialysis patients.

Adequacy of dialysis and differences in hematocrit among dialysis facilities

Despite the clearly established relationship between adequacy of dialysis and response to erythropoietin, recent guidelines on anemia management in end-stage renal disease (ESRD) omit mention of dialysis adequacy while advocating the use of large amounts of intravenous iron. To determine the relative effects of adequacy of dialysis and intravenous iron on hematocrit, we studied 309 hemodialysis patients and analyzed data from 141 hemodialysis facilities in New York State (ESRD Network 2), as well as data from all 18 ESRD Networks in the United States, for the last quarter of 1997. Among the 309 subjects, mean hematocrit differed between quartiles of urea reduction ratio (URR; F statistic = 4; P: = 0.008). Patients with URRs greater than 70% were 2.6 times more likely to have hematocrits greater than 33% (odds ratio, 2.6; 95% confidence interval [CI], 1.3 to 5.3; P: = 0.009) after adjustment for other factors. Mean dialysis facility (n = 141) hematocrits correlated directly with mean URRs (r = 0.32; P: = 0.001). Facilities with a mean URR greater than 70% were three times more likely to have a mean hematocrit greater than 33% (odds ratio, 3; 95% CI, 1.2 to 7.5; P: = 0.02). The percentage of patients in each of the 18 ESRD Networks with hematocrits of 33% or greater correlated inversely with the percentage of patients administered intravenous iron (r = -0.53; P: = 0.03) after adjustment for dose of erythropoietin. We conclude that adequacy of dialysis predicts the response to erythropoietin at both patient and dialysis facility levels. Patients with low hematocrits primarily because of inadequate dialysis may inappropriately be administered excess intravenous iron intended as a corrective measure.

Erythropoietin, iron, and erythropoiesis

Recent knowledge gained regarding the relationship between erythropoietin, iron, and erythropoiesis in patients with blood loss anemia, with or without recombinant human erythropoietin therapy, has implications for patient management. Under conditions of significant blood loss, erythropoietin therapy, or both, iron-restricted erythropoiesis is evident, even in the presence of storage iron and iron oral supplementation. Intravenous iron therapy in renal dialysis patients undergoing erythropoietin therapy can produce hematologic responses with serum ferritin levels up to 400 μg/L, indicating that traditional biochemical markers of storage iron in patients with anemia caused by chronic disease are unhelpful in the assessment of iron status. Newer measurements of erythrocyte and reticulocyte indices using automated counters show promise in the evaluation of iron-restricted erythropoiesis. Assays for serum erythropoietin and the transferrin receptor are valuable tools for clinical research, but their roles in routine clinical practice remain undefined. The availability of safer intravenous iron preparations allows for carefully controlled studies of their value in patients undergoing erythropoietin therapy or experiencing blood loss, or both.

Erythropoietin, iron, and erythropoiesis

Recent knowledge gained regarding the relationship between erythropoietin, iron, and erythropoiesis in patients with blood loss anemia, with or without recombinant human erythropoietin therapy, has implications for patient management. Under conditions of significant blood loss, erythropoietin therapy, or both, iron-restricted erythropoiesis is evident, even in the presence of storage iron and iron oral supplementation. Intravenous iron therapy in renal dialysis patients undergoing erythropoietin therapy can produce hematologic responses with serum ferritin levels up to 400 μg/L, indicating that traditional biochemical markers of storage iron in patients with anemia caused by chronic disease are unhelpful in the assessment of iron status. Newer measurements of erythrocyte and reticulocyte indices using automated counters show promise in the evaluation of iron-restricted erythropoiesis. Assays for serum erythropoietin and the transferrin receptor are valuable tools for clinical research, but their roles in routine clinical practice remain undefined. The availability of safer intravenous iron preparations allows for carefully controlled studies of their value in patients undergoing erythropoietin therapy or experiencing blood loss, or both.

End-stage renal disease (ESRD) and vascular access grafting: a critical review

End-Stage Renal Disease (ESRD) is a major disease state, costing the U.S. $9.5 billion in 1992, and increasing 10% yearly. The growth in the number of ESRD patients can be attributed principally to demographic trends: the aging of the general population and the improved treatment and increased survival rate of patients with diabetes, hypertension, and other illnesses that lead to ESRD. Moreover, improved dialysis technology has enabled older patients and those who previously could not tolerate dialysis due to other illnesses to benefit from this treatment. Three modalities exist for the treatment of ESRD: hemodialysis, peritoneal dialysis, and kidney transplant. This article reviews the medical treatments and the synthetic polymers used in the manufacture of vascular access grafts. We report on the development of a new, polyurethane-based microporous vascular graft, which displays self-sealing and improved compliance characteristics for use in vascular access grafting.

Decreased affinity and number of transferrin receptors on erythroblasts in the anemia of rheumatoid arthritis

In anemia of chronic disease (ACD) in rheumatoid arthritis (RA) a decreased iron uptake and transferrin binding by erythroblasts are postulated to play a pathophysiological role. To examine whether this is related to changes in transferrin receptor expression by erythroblasts, we studied bone marrow from 5 healthy controls, 5 nonanemic RA patients, and 9 RA patients with ACD. Bone marrow mononuclear cells were incubated with increasing concentrations of 125I-transferrin and specific binding data were analyzed by the method of Scatchard. The number of transferrin receptors on erythroblasts from RA patients with ACD was significantly lower as compared to nonanemic RA patients (P < .05) and controls (P < .02). The affinity of the transferrin receptor tended to be lower in ACD. These preliminary data may indicate that transferrin receptor expression by erythroblasts is impaired in ACD. Since the rate of erythroid iron uptake is mainly determined by the number of transferrin binding sites, this may explain a decrease in erythroblast iron availability in ACD in RA.

Transferrin microheterogeneity in rheumatoid arthritis. Relation with disease activity and anemia of chronic disease

We studied the relation between disease activity in rheumatoid arthritis (RA) and the microheterogeneity of transferrin. Using crossed immuno isoelectric focusing, transferrin microheterogeneity patterns were analyzed in sera of healthy individuals, nonanemic RA patients, iron deficient RA patients and RA patients with the anemia of chronic disease (ACD). In all RA groups a significant shift in the microheterogeneity pattern was observed, reflecting increased synthesis of transferrins with highly branched glycan chains. Increased disease activity correlated with both the induction of ACD and the change in transferrin glycosylation, which was, therefore, most pronounced in ACD. Generally, an increased synthesis of glycoproteins is accompanied by alterations in their glycosylation pattern. Since transferrin is a negative acute phase protein, our results indicated that changes in synthetic rates and changes in glycosylation induced in the acute phase response are regulated independently.

Tumor necrosis factor alpha is associated with disease activity and the degree of anemia in patients with rheumatoid arthritis

To elucidate the role of tumor necrosis factor alpha (TNF) in determining anemia of chronic disease (ACD) in rheumatoid arthritis (RA), 24 patients were studied for disease parameters, TNF serum levels and bone marrow for erythroid colony growth and compared with six controls. Serum TNF alpha was highest in ACD and correlated well with RA disease parameters. Both TNF and other RA disease parameters correlated inversely with degree of anemia. BFUe counts were lower in ACD, correlated positively with Hb and negatively with erythrocyte sedimentation rate (ESR). TNF reduced whereas anti-TNF upregulated in vitro erythroid colony counts. TNF production occurred in similar amounts in bone marrow cultures in the three groups. From these preliminary findings we conclude that ACD in RA correlates with by RA disease activity and that TNF may serve not only as an RA disease marker but also could be one of the factors mediating impaired erythropoiesis in ACD in active RA.

Anemia of chronic disease

ACD is probably the most common anemia among hospitalized medical patients. It is variably defined by its clinical and, particularly, its laboratory manifestations. The most consistent features are low serum iron and normal or increased serum ferritin levels, reflecting normal or increased iron stores and distinguishing ACD from iron deficiency anemia. ACD often coexists with iron deficiency and the anemia of renal insufficiency. Most patients have an underlying infectious, inflammatory, or neoplastic disease, but as many as one quarter of patients do not. Several mechanisms have been proposed, the most significant of which are a block in reutilization of hemoglobin iron for red cell production and relative deficiency of erythropoietin, but the pathogenesis and mediators involved remain uncertain. The anemia itself seldom requires treatment and is ameliorated by successful treatment of the underlying disease.

Anaemia of chronic disease in rheumatoid arthritis. Raised serum interleukin-6 (IL-6) levels and effects of IL-6 and anti-IL-6 on in vitro erythropoiesis

Serum and bone marrow from 21 patients with rheumatoid arthritis (RA) were studied in order to establish the pathogenetic role of interleukin-6 (IL-6) in anemia of chronic disease (ACD). Erythroid colony growth, using burst forming units of erythroblasts (BFUe) as a parameter, was impaired in ACD and not in nonanemic RA controls. Serum IL-6 was elevated in ACD and it correlated well with parameters of disease activity such as erythrocyte sedimentation rate and C-reactive protein. IL-6 addition to bone marrow cultures had inconsistent effects while anti-IL-6 addition resulted in impaired erythroid colony growth, suggesting stimulatory effects of IL-6 produced in the medium, which may be masked by simultaneous production of cytokines with suppressive effects. It was concluded that elevated serum IL-6 in ACD reflects disease activity. It probably plays no pathogenetic role in ACD. Its stimulatory effects on erythroid growth might counteract suppressive effects of other interleukins.

The role of erythropoietin in the anaemia of chronic disease in rheumatoid arthritis

We reviewed studies on the role of erythropoietin (Epo) in the anaemia of chronic disease (ACD) in rheumatoid arthritis (RA). A relatively impaired Epo response to the anaemia was found in a number of studies although in others serum Epo level was the same as in other types of anaemia. Some arguments are found in favor of a reduced bone marrow-Epo sensitivity although these reflect results mainly from in vitro experiments. It is not yet established whether bone marrow macrophage Epo production is impaired in ACD. In two cases Epo administration to RA patients resulted in increased erythropoiesis. It was concluded that impaired Epo production or reduced bone marrow Epo sensitivity might be associated with ACD but it is not certain whether these factors are causally linked with ACD or side phenomena of RA disease activity. Future Epo treatment in RA and ACD will possibly solve this question.

Anaemia in rheumatoid arthritis: the role of iron, vitamin B12, and folic acid deficiency, and erythropoietin responsiveness

Thirty six patients with rheumatoid arthritis (RA) (25 with anaemia) were studied to establish the role of iron, vitamin B12, and folic acid deficiency, erythropoietin responsiveness, and iron absorption in the diagnosis and pathogenesis of anaemia in RA. Iron deficiency, assessed by stainable bone marrow iron content, occurred in 13/25 (52%), vitamin B12 deficiency in 7/24 (29%), and folic acid deficiency in 5/24 (21%) of the anaemic patients. Only 8/25 (32%) had just one type of anaemia. The iron deficiency of anaemia of chronic disease (ACD) was distinguished by ferritin concentration, which was higher in that group. Mean cell volume (MCV) and mean cell haemoglobin (MCH) were lower in both anaemic groups, but most pronounced in iron deficient patients. Folic acid, and especially vitamin B12 deficiency, masked iron deficiency by increasing the MCV and MCH. Iron absorption tended to be highest in iron deficiency and lowest in ACD, suggesting that decreased iron absorption is not a cause of ACD in RA. No specific causes were found for vitamin B12 or folic acid deficiency. Haemoglobin concentration was negatively correlated with erythrocyte sedimentation rate in the group with ACD. Erythropoietin response was lower in ACD than in iron deficient patients. It was concluded that generally more than one type of anaemia is present simultaneously in anaemic patients with RA. The diagnosis of each type may be masked by another. Studies on pathogenesis of the anaemia are difficult as deficiencies generally coexist with ACD. Disease activity and, possibly, erythropoietin responsiveness are major factors in ACD pathogenesis.

Anaemia in rheumatoid arthritis: pathogenesis, diagnosis and treatment

The pathogenesis, diagnosis and treatment of the anaemia of chronic disorders (ACD) in rheumatoid arthritis (RA) were reviewed. Causes of anaemia other than ACD frequently present in RA. Decreased iron absorption was shown to be the result of active RA rather than a cause of ACD or iron deficiency. It has been hypothesized that bone marrow iron availability decreases due to decreased iron release by the mononuclear phagocyte system or that the anaemia in ACD is due to ineffective erythropoiesis; these remain controversial theories. Studies considering a decreased erythropoietin responsiveness have not produced consistent results. Erythroid colony growth is suppressed in vitro by interleukins and tumour necrosis factor but their role in vivo in ACD is unknown. The diagnosis of ACD is made by exclusion. Iron deficiency is detected by transferrin, ferritin, and cellular indices after adaptation of their normal values. Treatment of the anaemia consists merely of antirheumatic treatment. Iron administration is counterproductive since iron chelators or exogenous erythropoietin administration might increase erythropoiesis.

The anemia of chronic disease: spectrum of associated diseases in a series of unselected hospitalized patients

PURPOSE

Previous studies of the anemia of chronic disease (ACD) have generally begun with patients afflicted with one of the classical underlying diseases such as rheumatoid arthritis. The clinical spectrum of ACD has not been thoroughly examined. We hypothesized that many patients have an anemia with the characteristics of ACD but do not have one of the infectious, inflammatory, or neoplastic disorders usually associated with ACD. We therefore evaluated a series of consecutive, unselected, anemic patients admitted to a county hospital.

PATIENTS AND METHODS

All patients admitted to the medicine ward service of a county hospital were screened for anemia (hematocrit less than 40% in men, less than 37% in women). Additional laboratory data were collected on all anemic patients, except those with active gastrointestinal bleeding, hemolytic disease, or leukemia or multiple myeloma. The patients were divided into three groups on the basis of serum values indicating iron distribution: iron deficiency (serum ferritin less than 10 ng/mL), ACD (serum iron less than 60 micrograms/dL and serum ferritin more than 50 ng/mL), and all others (non-ACD). The hospital records of the patients in the latter two groups were reviewed and their diagnoses recorded.

RESULTS

Seven patients with iron deficiency were not considered further. Ninety patients with ACD were compared with 75 patients with non-ACD. The anemia in ACD patients was more severe than most authors describe. The mean hematocrit was 31%, and 20% of patients had hematocrits below 25%. The anemia was usually normocytic (mean red cell volume [MCV] 86 fL), but 21% had an MCV less than 80 fL. The level of saturation of serum iron-binding capacity was quite low in ACD (mean 15%) and was normal in non-ACD (mean 31%). Renal insufficiency was common in both groups; serum creatinine values were more than 2 mg/dL in 31% of patients with ACD and 20% of non-ACD patients. Sixty percent of patients with ACD had a principal diagnosis that fell into the infectious, inflammatory, and neoplastic categories commonly associated with ACD. Renal insufficiency was the major diagnosis in 16%, and the principal diagnosis in 24% was a disease not commonly considered to be associated with ACD. In non-ACD patients, the principal diagnosis was an infectious, inflammatory, or neoplastic disease in 55%, renal insufficiency in 9%, and another disease in 36%.

CONCLUSIONS

When ACD was defined by the abnormalities of iron distribution, which are its most consistent and widely accepted characteristics, the spectrum of associated diseases was much broader than the traditional categories of infectious, inflammatory, and neoplastic disorders, and the overlap with non-ACD was large. Until the etiologic and pathogenetic mechanisms of ACD are better understood, a flexible and inclusive view of this disorder seems appropriate.

Prediction and evaluation of the effect of iron treatment in anaemic RA patients

In order to predict a haemoglobin (Hb) rise, in response to treatment with iron from simple erythrocyte and serological parameters, we treated 28 anaemic RA patients with oral iron during 6 weeks. Iron deficiency, present in 57% of patients, was assessed by staining a bone marrow aspirate for iron. Response rate in this group was 81% and median Hb increase was 0.8 mmol/l. After 6 weeks 69% of iron deficient patients were still anaemic. Patients without iron deficiency, considered as having anaemia of chronic disease (ACD), showed no significant Hb rise. The finding of a hypochromic microcytic anaemia was associated with a significant Hb rise. MCV showed highest specificity and predictive value (90 and 88%) and ferritin was the most valid predictor of a Hb rise within 6 weeks. Combination of low MCV and low ferritin resulted in a 100% specificity and predictive value indicating that patients with values below cut off point of these variables will definitely respond to treatment. Disease activity tended to decrease after 6 weeks, but this was not correlated with a Hb rise. It was concluded that a Hb rise can be predicted accurately by blood parameters. Using certain combinations, bone marrow aspiration is rarely necessary. Iron treatment is only useful in iron deficient RA patients, although active RA limits maximal Hb rise. In contrast to earlier findings, iron treatment had no deleterious effects on disease activity.

Studies on the rat liver following iron overload: an analysis of iron and lysosomal enzymes in isolated parenchymal and non-parenchymal cells

Iron overload is known to affect the liver. In order to study the effect of iron on various liver cellular and subcellular compartments and the alterations due to mobilization of iron, an experimental model has been developed previously. In this study iron stores in parenchymal and non-parenchymal cells have been investigated during iron loading and unloading. Following completion of the experimental procedures, liver cells were isolated by means of collagenase perfusion (parenchymal cells) and pronase treatment (nonparenchymal cells). It was found that iron overload did not result in significantly increased levels of three lysosomal enzymes, and that the enzyme activities were not altered as iron was mobilized. Iron stores were localized largely in parenchymal cells, and these stores decreased after cessation of iron loading. The iron content was further lowered if the animals were bled. The non-parenchymal cells of the liver initially stored a relatively small part of the administered iron but this increased in the two months following iron loading. On the other hand if the animals were bled there was a pronounced decrease in iron content of these cells as well as in parenchymal cells. It is concluded that iron overload does not affect lysosomal enzymes and that iron stores in both parenchymal and non-parenchymal cells can be mobilized in response to increased demand.

Serum ferritin in non-dialysis patients with chronic renal failure: relation to bone marrow iron stores

Serum ferritin and bone marrow haemosiderin iron was studied in 50 non-dialysis patients with chronic renal failure, and in 53 healthy subjects. S-ferritin was correlated to marrow iron both in patients with renal failure and in healthy subjects (P less than 0.001). Geometric-mean S-ferritin in patients with 0- (1+) marrow iron was 33 micrograms/l, 1+ marrow iron 166 micrograms/l, and 2+ marrow iron 519 micrograms/l. Healthy subjects with 0- (1+) marrow iron had a mean S-ferritin of 16 micrograms/l and those with 1+ marrow iron a value of 65 micrograms/l. S-ferritin levels were higher in patients than in healthy subjects at all marrow iron grades (P less than 0.001). Healthy subjects with S-ferritin less than 15 micrograms/l had absent or reduced marrow iron, while those with S-ferritin greater than 30 micrograms/l had normal marrow iron. Using a critical S-ferritin value of less than or equal to 20 micrograms/l, the diagnostic efficiency in terms of diagnosing absent or reduced marrow iron was 0.90 (PV pos = 0.85, Pv neg = 0.91). In patients with renal failure S-ferritin less than 60 micrograms/l indicated absent or reduced marrow iron, while values greater than 80 micrograms/l were associated with normal marrow iron. The diagnostic efficiency of S-ferritin using a critical value of less than or equal to 60 micrograms/l was 0.94 (PV pos = 0.93, PV neg = 0.97). S-ferritin is a useful indicator of marrow iron stores in patients with chronic renal failure.

In-vitro studies of ineffective erythropoiesis in rheumatoid arthritis

Ineffective erythropoiesis was assessed in a series of 32 patients with rheumatoid arthritis by means of a new in-vitro method which measures the release of haem from a labelled cohort of erythroblasts in culture. Haem release was significantly increased in patients with the anaemia of chronic disorders but was normal in those who were not anaemic or who had an iron-deficiency anaemia. In 2 patients with anaemia of chronic disorders haem release returned to normal after successful antirheumatic therapy. The increased ineffective erythropoiesis in patients with rheumatoid arthritis and anaemia of chronic disorders appeared to be unrelated to functional iron deficiency and was not attributable to a serum factor.

Release of iron by resident and stimulated mouse peritoneal macrophages following ingestion and degradation of transferrin-antitransferrin immune complexes

A method of loading macrophages from normal and inflammatory mouse peritoneal exudates with 59Fe using 59Fe, 125I-transferrin-antitransferrin immune complexes is described and the subsequent release of iron and degraded transferrin to the incubation medium has been studied. Release of iron occurred more rapidly from resident macrophages than from thioglycollate broth-induced (stimulated) macrophages, but degradation of the 125I-transferrin in the immune complexes was faster in stimulated cells. A small percentage of the iron released was in the form of ferritin. Desferrioxamine (1 mM) increased the release of iron from both stimulated and resident macrophages, the effect being proportionally greater in the stimulated cells. Ascorbic acid (1 mM) had no effect on the release of iron, nor did the addition of apotransferrin (1 mg/ml) to the culture medium. These results support the concept of a blockade of iron release by reticuloendothelial cells in states of inflammation, and suggest that it may be a primary cause of the anaemia of chronic disease.

Diagnostic efficiency of various laboratory tests in the assessment of bone marrow iron stores in patients with chronic uraemia

Bone marrow haemosiderin iron was correlated with various laboratory parameters of iron status in order to define a reliable laboratory index of marrow iron stores. Marrow iron, serum iron, plasma transferrin, transferrin saturation, iron absorption, red cell iron incorporation and serum ferritin were measured in 21 non-dialysed, 20 peritoneal dialysed and 34 haemodialysed patients with chronic uraemia. Diagnostic accuracy of the laboratory tests in terms of diagnosing reduced marrow iron stores was expressed as the predictive value of a positive test and a negative test, and efficiency. Diagnostic efficiency of serum iron, plasma transferrin and transferrin saturation was too low to be of value in the individual patient. Iron absorption and red cell incorporation had a higher diagnostic efficiency, but are unpractical for routine use. Serum ferritin displayed a high diagnostic efficiency and appears to be a reliable index of marrow iron stores, suitable for sequential monitoring of iron status in uraemic subjects.

Studies on the rat liver following iron overload

Sprague-Dawley rats were given Jectofer injections to obtain iron overload in rat liver Kupffer and parenchymal cells. The release of iron was studied on the light and electron microscopical level by bleeding of the iron loaded animals and comparing the results with non bled controls. During the mobilization of iron. Kupffer cells showed a rapid and almost complete disappearance of electron dense iron containing particles (IP) while there was only limited decline of IPs in the parenchymal cells. Iron was demonstrated with X-ray microanalysis at the ultrastructural level, and presence of acid phosphatase was revealed using a histochemical method based on precipitation of lead phosphate at sites of enzyme activity in combination with X-ray microanalysis. It was demonstrated that all IP-containing cytoplasmic bodies also showed presence of acid phosphatase implying that all of them represented lysosomes. The mechanism of release of iron from Kupffer and parenchymal cells was discussed with special emphasis on the role of the lysosomes and the relationship between their contents and other cellular structures.

Morphological changes of the liver in uremic patients treated with chronic hemodialysis--laparoscopic observations and light- and electron-microscopic studies

In order to clarify morphological changes of the liver in the uremic state, 16 uremic patients treated with chronic hemodialysis were studied. Biopsy was performed in 14 cases under laparoscopic observation and in two on the occasion of renal transplantation. One uremic patients not being treated with dialysis was also studied for comparison. All biopsy specimens were examined by light and electron microscopy. The liver usually appeared mildly or moderately swollen under laparoscopic observations, which was considered at least partially due to the enlargement of the hepatocytes. All patients had hepatocytes with an Orcein-negative "ground glass" appearance, in which marked proliferation of smooth endoplasmic reticulum (SER) was found by electron microscopy. Since the patient not being on dialysis also had such hepatocytes, this finding may be characteristic of uremia. With electron microscopy, in addition to proliferation of SER, alteration of mitochondria and rough endoplasmic reticulum (RER) and an increase in cytoplasmic lipid droplets were observed. Hypertrophy of the Golgi apparatus containing electron-dense particles (VLDL) was often found in patients associated with hypertriglyceridemia. Amorphous electron-dense inclusions in microbodies were occasionally observed. Siderosis was observed in nine patients including three having parenchymal siderosis. With electron microscopy, various siderosomes were seen in the cytoplasm of hepatocytes in patients with parencymal siderosis. Conclusively, these histological and ultrastructral features of hepatocytes are rather associated with several metabolic abnormalities in uremia.

A method for the investigation of reticuloendothelial iron kinetics in man

A colloidal suspension of hydrolysed radio-iron of high specific activity has been developed for the investigation of reticuloendothelial (RE) iron kinetics in man. Following intravenous injection this material is cleared rapidly by the RE system and the iron released intn to the endogenous RE iron load, and it has proved possible to measure RE iron release without disturbing the normal iron flow.

Role of ineffective erythropoiesis in the anaemia of rheumatoid arthritis

The importance of inadequate haemoglobin synthesis and ineffective erythropoiesis in the anaemia of rheumatoid arthritis was studied by measuring the incorporation of 15N glycine into haemoglobin haem and early labelled bilirubin in a patient with severe anaemia before and after response to gold therapy. Initially, total erythroid haem turnover was decreased but haem turnover due to ineffective erythropoiesis was markedly increased, accounting for 29% of total erythroid haem turnover. Gold therapy resulted in marked clinical improvement, accompanied by a rise in haemoglobin to normal. Total erythroid haem turnover increased and the percentage ineffective erythropoiesis fell to normal. Ineffective erythropoiesis may thus be an important reversible factor in the production of the anaemia of rheumatoid arthritis.