COMPARISON OF HEMOSIDERIN ESTIMATION IN BONE MARROW SECTIONS AND BONE MARROW SMEARS

Serum or plasma ferritin concentration as an index of iron deficiency and overload

BACKGROUND

Reference standard indices of iron deficiency and iron overload are generally invasive, expensive, and can be unpleasant or occasionally risky. Ferritin is an iron storage protein and its concentration in the plasma or serum reflects iron stores; low ferritin indicates iron deficiency, while elevated ferritin reflects risk of iron overload. However, ferritin is also an acute-phase protein and its levels are elevated in inflammation and infection. The use of ferritin as a diagnostic test of iron deficiency and overload is a common clinical practice.

OBJECTIVES

To determine the diagnostic accuracy of ferritin concentrations (serum or plasma) for detecting iron deficiency and risk of iron overload in primary and secondary iron-loading syndromes.

SEARCH METHODS

We searched the following databases (10 June 2020): DARE (Cochrane Library) Issue 2 of 4 2015, HTA (Cochrane Library) Issue 4 of 4 2016, CENTRAL (Cochrane Library) Issue 6 of 12 2020, MEDLINE (OVID) 1946 to 9 June 2020, Embase (OVID) 1947 to week 23 2020, CINAHL (Ebsco) 1982 to June 2020, Web of Science (ISI) SCI, SSCI, CPCI-exp & CPCI-SSH to June 2020, POPLINE 16/8/18, Open Grey (10/6/20), TRoPHI (10/6/20), Bibliomap (10/6/20), IBECS (10/6/20), SCIELO (10/6/20), Global Index Medicus (10/6/20) AIM, IMSEAR, WPRIM, IMEMR, LILACS (10/6/20), PAHO (10/6/20), WHOLIS 10/6/20, IndMED (16/8/18) and Native Health Research Database (10/6/20). We also searched two trials registers and contacted relevant organisations for unpublished studies.

SELECTION CRITERIA

We included all study designs seeking to evaluate serum or plasma ferritin concentrations measured by any current or previously available quantitative assay as an index of iron status in individuals of any age, sex, clinical and physiological status from any country.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. We designed the data extraction form to record results for ferritin concentration as the index test, and bone marrow iron content for iron deficiency and liver iron content for iron overload as the reference standards. Two other authors further extracted and validated the number of true positive, true negative, false positive, false negative cases, and extracted or derived the sensitivity, specificity, positive and negative predictive values for each threshold presented for iron deficiency and iron overload in included studies. We assessed risk of bias and applicability using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. We used GRADE assessment to enable the quality of evidence and hence strength of evidence for our conclusions.

MAIN RESULTS

Our search was conducted initially in 2014 and updated in 2017, 2018 and 2020 (10 June). We identified 21,217 records and screened 14,244 records after duplicates were removed. We assessed 316 records in full text. We excluded 190 studies (193 records) with reasons and included 108 studies (111 records) in the qualitative and quantitative analysis. There were 11 studies (12 records) that we screened from the last search update and appeared eligible for a future analysis. We decided to enter these as awaiting classification. We stratified the analysis first by participant clinical status: apparently healthy and non-healthy populations. We then stratified by age and pregnancy status as: infants and children, adolescents, pregnant women, and adults. Iron deficiency We included 72 studies (75 records) involving 6059 participants. Apparently healthy populations Five studies screened for iron deficiency in people without apparent illness. In the general adult population, three studies reported sensitivities of 63% to 100% at the optimum cutoff for ferritin, with corresponding specificities of 92% to 98%, but the ferritin cutoffs varied between studies. One study in healthy children reported a sensitivity of 74% and a specificity of 77%. One study in pregnant women reported a sensitivity of 88% and a specificity of 100%. Overall confidence in these estimates was very low because of potential bias, indirectness, and sparse and heterogenous evidence. No studies screened for iron overload in apparently healthy people. People presenting for medical care There were 63 studies among adults presenting for medical care (5042 participants). For a sample of 1000 subjects with a 35% prevalence of iron deficiency (of the included studies in this category) and supposing a 85% specificity, there would be 315 iron-deficient subjects correctly classified as having iron deficiency and 35 iron-deficient subjects incorrectly classified as not having iron deficiency, leading to a 90% sensitivity. Thresholds proposed by the authors of the included studies ranged between 12 to 200 µg/L. The estimated diagnostic odds ratio was 50. Among non-healthy adults using a fixed threshold of 30 μg/L (nine studies, 512 participants, low-certainty evidence), the pooled estimate for sensitivity was 79% with a 95% confidence interval of (58%, 91%) and specificity of 98%, with a 95% confidence interval of (91%, 100%). The estimated diagnostic odds ratio was 140, a relatively highly informative test. Iron overload We included 36 studies (36 records) involving 1927 participants. All studies concerned non-healthy populations. There were no studies targeting either infants, children, or pregnant women. Among all populations (one threshold for males and females; 36 studies, 1927 participants, very low-certainty evidence): for a sample of 1000 subjects with a 42% prevalence of iron overload (of the included studies in this category) and supposing a 65% specificity, there would be 332 iron-overloaded subjects correctly classified as having iron overload and 85 iron-overloaded subjects incorrectly classified as not having iron overload, leading to a 80% sensitivity. The estimated diagnostic odds ratio was 8.

AUTHORS' CONCLUSIONS

At a threshold of 30 micrograms/L, there is low-certainty evidence that blood ferritin concentration is reasonably sensitive and a very specific test for iron deficiency in people presenting for medical care. There is very low certainty that high concentrations of ferritin provide a sensitive test for iron overload in people where this condition is suspected. There is insufficient evidence to know whether ferritin concentration performs similarly when screening asymptomatic people for iron deficiency or overload.

What is the evidence for gender differences in ferritin and haemoglobin?

Reference ranges for haemoglobin and ferritin in women of reproductive age are widely reported showing values that are lower than equivalent aged males. Similar values would be expected in the absence of different biological requirements. While reference ranges have been derived from data on large populations, it is likely that these populations have included significant numbers of women who are iron deficient in view of menstrual blood loss and poor dietary intake. Populations with a daily iron intake in excess of 100mg have shown that iron deficiency in females is rare. Studies reporting bone marrow with iron stains from 50 years ago pointed out that significant numbers of women were iron deficient and more recently serum ferritin studies have confirmed this. However, a large number of women in the Western world spend a significant part of their lives in a negative iron balance due to a combination of poor diet and menstrual blood loss. The presence of haem iron in the diet of humans enhances non-haem iron absorption but dietary surveys consistently report that women's diet is deficient in iron. Furthermore, the typical Western diet contains many common foods that limit iron absorption. It appears that lower haemoglobin and ferritin values in menstruating women have been accepted as normal rather than possibly representing widespread iron deficiency. Reference ranges should be re-evaluated in populations proven to be iron replete.

The differentiation of anaemia in rheumatoid arthritis: parameters of iron-deficiency in an Indian rheumatoid arthritis population

Iron deficiency anaemia (IDA) is common in Indian patients with rheumatoid arthritis (RA). We evaluated red blood cell indices, serum iron related and bone marrow iron stores measurements in diagnosing iron deficiency in patients with RA. Fifty consecutive anaemic patients with RA had their complete blood counts, red cell indices, serum iron, serum ferritin and serum total iron binding capacity (TIBC) measured and underwent posterior iliac crest bone marrow aspiration. Fixed smears were stained for iron with Perl's Prussian blue and patients who had no (grade 0) or minimal stainable iron (grade I) were regarded as iron deficient and rest iron replete (grade II-IV) and hence as having anaemia of chronic disease (ACD). To determine diagnostic power of tests used for diagnosing iron deficiency in addition to positive likelihood ratio, sensitivity, specificity and negative predictive values; receiver operating characteristics (ROC) curves were plotted and areas under the receiver-operating curves were compared. Eighteen patients (36%) had IDA and 32 (64%) had ACD. Correlation between the bone marrow iron stores and serum ferritin was poor in the IDA group (r = -0.09, P = 0.57) and significant in the ACD group (r = 0.79, P < 0.0001). Areas under the ROC curves for mean corpuscular haemoglobin (MCV), serum iron, TIBC and mean corpuscular haemoglobin concentration (MCHC) were relatively low (0.52, 0.71, 0.75 and 0.77, respectively) and these tests had low positive likelihood ratios (1.08, 2.13, 4.62 and 1.5, respectively). Both area under ROC curve [0.98, 95% confidence interval (0.94, 0.99)] and negative predictive value (97%) were highest when cut off serum ferritin was <82 microg/l. In patients with RA serum iron, TIBC, MCV and MCHC have limited value in diagnosing iron deficiency. In this study compared to American and European studies a much higher cut off value of serum ferritin had most diagnostic power for detecting iron deficiency. Bone marrow iron stores measurements appears to be the most reliable method for diagnosing IDA however, it needs to be taken in conjunction with other laboratory findings and the clinical scenario.

Effect of recombinant human erythropoietin on anaemia and disease activity in patients with rheumatoid arthritis and anaemia of chronic disease: a randomised placebo controlled double blind 52 weeks clinical trial

OBJECTIVE

To study whether recombinant human erythropoietin (r-hu-Epo) improves anaemia and reduces disease activity in patients with rheumatoid arthritis and anaemia of chronic disease (ACD).

METHODS

A 52 week placebo controlled randomised double blind trial with r-hu-Epo was performed in 70 patients with active rheumatoid arthritis and ACD. Thirty four patients were treated with 240 U kg-1 r-hu-Epo subcutaneously, initially three doses weekly, while 36 patients received placebo.

RESULTS

A significant increase of haemoglobin from a median of 112 to 135 g litre-1 occurred in the Epo group within six weeks and could be sustained with reduced doses (median 240 U kg-1 once weekly). Sustained benefit compared to placebo was also apparent by six weeks for disease activity, as indicated by the Paulus 20% response rate. Of patients in the Epo group, 32% eventually showed a Paulus 20% response, compared to 8% of the placebo group (P = 0.016). Significant differences in favour of the Epo group were also observed in the secondary disease activity measures Ritchie index, number of swollen joints, pain score, ESR, and patients' global assessment of disease activity. C reactive protein concentrations did not change significantly.

CONCLUSIONS

Treatment of ACD in rheumatoid arthritis with r-hu-Epo is effective in restoring normal haemoglobin levels and also exerts a beneficial effect on disease activity.

Screening for iron deficiency: an analysis based on bone-marrow examinations and serum ferritin determinations in a population sample of women

Efficacy of different methods in screening for iron deficiency was re-examined in a randomly selected sample of 38-year-old women (n = 203) with known iron status based on absence/presence of stainable iron in bone-marrow smears. The study was made in 1968-69. Serum ferritin (SF) was determined in 1978 in frozen sera using the Ramco IRMA and, in 1992, samples were re-analysed using a RIA calibrated with the International Standard 80/602 for SF determination. The effect of storage on SF was calculated from a previously established relationship (courtesy of Dr Mark Worwood, Cardiff) between the results obtained with the Ramco assay and assays calibrated with IS 80/602. The distributions in iron replete and iron deficient women showed less overlap (diagnostic efficiency 91%) for SF than for other haematological parameters. The best discrimination was obtained at SF < 16 micrograms/l (specificity 98%; sensitivity 75%). Absence of iron stores was associated with signs of an iron deficient erythropoiesis, starting already at SF 25-40 micrograms/l. Use of multiple criteria to diagnose iron deficiency falsely reduces prevalence figures for iron deficiency.

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.

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 pathogenesis of anemia in rheumatoid arthritis: a clinical and laboratory analysis

Principal concepts concerning the anemia of RA are summarized in Tables 7 and 8. These concepts have been validated by our analysis of 93 anemic RA patients and by our review of the literature. The fact that anemia in RA may have one or more etiologies, occasionally in the same patient, mandates a reasoned approach to the analysis of anemia in every RA patient in whom it may occur. In particular, iron deficiency is common and determination of bone marrow iron content via an aspirate may be required for a definitive diagnosis. In those RA patients with anemia of chronic disease, the best therapy remains control of the underlying disease, most commonly with second line drugs and/or corticosteroids. The place for recombinant erythropoietin in the therapy of this anemia has not been defined; one specific role for erythropoietin may be in the preparation of RA patients for elective surgery, particularly hip arthroplasty, where correction of the anemia may either obviate the need for transfusion or may allow for donation of blood for purposes of autologous transfusion perioperatively. The pathogenesis of the anemia of chronic disease, as seen in RA anemia, is not completely understood. Inflammatory mediators, particularly the cytokines, appear to be important factors in the impairment of erythropoiesis. The mechanism by which these cytokines impair erythroid progenitor growth and hemoglobin production in developing erythrocytes is an important area for future study.

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.

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.

Haematological findings in chronic alcoholics after heavy drinking with special reference to haemolysis

Haematological abnormalities are frequently found in heavy-drinking chronic alcoholics, but anaemia is generally a rare complication. When present, haemolysis is considered to be one of the most common causes. However, little is known about mild haemolysis without anaemia. The present report on eighteen male chronic alcoholics with a recent heavy debauche but without signs of severe liver disease gave support for the occurrence of a reversible low-degree haemolysis without concomitant gross changes of the erythrocytes. Thus the bone marrow showed an increased erythropoiesis in the absence of iron deficiency and known blood losses. Further, increased reticulocyte counts and low levels of haemopexin were noted in the early abstinence. Finally, during the withdrawal phase haptoglobin and haemopexin increased concomitantly with diminishing values of unconjugated bilirubin. The most likely cause of the proposed diminished red cell survival before the withdrawal is supposed to be a reduced membrane stability.

Serum ferritin as a guide for iron stores in chronic hemodialysis patients

The serum ferritin (SF) level was measured in 58 chronic hemodialysis (CHD) patients (46 living and 12 deceased subjects) and compared to bone marrow iron concentrations, cytological bone marrow iron stores (BMIS), and histological BMIS. In the 12 deceased subjects, liver iron concentrations, histological liver parenchymal, and Kupffer cell iron stores were also studied. The mean SF level of the whole group was 302 +/- 251 ng/ml (mean +/- SD). No close relationship was found between transferrin saturation and cytological BMIS. A high correlation was found between SF level and cytological BMIS (Spearman rank rs = 0.74). In the deceased CHD patients a close correlation was observed between histological parenchymal liver iron stores and histological Kupffer cell iron stores, but not between liver and bone marrow iron stores. A good correlation was found between SF levels and liver iron concentrations. It is concluded that in CHD patients SF levels are higher than in healthy controls, even in the absence of iron therapy (except in the form of blood transfusions); in some of these patients iron is disproportionately stored in the bone marrow and the liver. Although the level of BMIS cannot be estimated unequivocally from an SF measurement in every CHD patient, SF levels provide useful estimates of BMIS.

Studies on histamine metabolism in mastocytosis

The urinary excretion of histamine and its main metabolite, 1-methyl-4-imidazoleacetic acid (MeImAA), was determined in 30 adult patients with the clinical diagnosis of urticaria pigmentosa (UP). Clinical and laboratory investigations including skin histology, bone marrow examination, and scintigraphy of the skeleton, liver, and spleen revealed systemic manifestations in 14 cases. Among the 16 cases with dermal proliferation of mast cells only 3 cases classified as telangiectasia macularis eruptiva perstans (TMEP). All patients with systemic mastocytosis and UP excreted increased amounts of MeImAA in the urine while normal amounts were found in 2 of the patients with TMEP. A significant correlation existed between MeImAA excretion and the extent of mast cell infiltration in skin and internal organs. No such correlation was found for urinary histamine. Urinary MeImAA but not histamine is therefore considered a useful indicator of systemic involvement by reflecting the size of the mast cell histamine pool. The main symptom of the patients was pruritus, which was moderate to severe in 17 and mild or absent in 13 cases. Gastrointestinal symptoms were present in 14 patients. However, there was no obvious correlation between the excretion of MeImAA and any of the symptoms recorded. Neither was the severity of pruritus correlated to the histamine content of the skin, which was measured in both lesional and unaffected skin in 23 of the patients. Thus, symptoms possibly caused by histamine in mastocytosis patients are not directly related to urinary histamine metabolite excretion or tissue histamine content.

Hematological findings in the Norrbottnian type of Gaucher disease

A controlled study of hematological changes was performed on 14 patients with the Norrbottnian type of Gaucher disease, seven of whom had been splenectomized at least one year before the study. Each patient had two controls matched to age, sex and habitation. Before splenectomy the patients had slight to moderate microcytic, hypochromic anemia which changed after splenectomy to macrocytic, hypochromic anemia. The splenectomized patients had a high percentage of target cells (mean frequency 33%) and a significantly increased hypo-osmotic resistance of the erythrocytes which showed a positive correlation with the number of target cells. Before removal of the spleen the patients had slight leukopenia with a relative increase of mononuclear cells and moderate thrombocytopenia. In the splenectomized patients the thrombocyte count was normal and there was moderate leukocytosis with a persistent relative increase of lymphocytes.

Serum iron and transferrin saturation in women with special reference to women with low transferrin saturation. The population study of women in Göteborg 1968-1969

Serum iron and total iron binding capacity (TIBC) were determined in a population sample of 1462 women in age strata between 38 and 60. Serum iron and TIBC values were similar in the various ages studied but with a slight trend towards higher serum iron and lower TIBC values in the upper ages. Transferrin saturation was used to divide the material arbitarily into women with and without iron deficiency. The dividing point chosen was 16%. The women thus defined as iron deficient had lower mean haemoglobin values than women in the total population sample and were more often anaemic. They had also lower MCV, MCH and MCHC indices than women in the total population sample. Of these indices, MCH seemed to discriminate the state of iron deficiency better than MCV and MCHC. Except for an increased mean menstrual blood loss no obvious cause of iron deficiency could be found in these women with low transferrin saturation.

Stainable iron in aspirated and needle-biopsy specimens of marrow: a source of error

Marrow iron was assessed in needle biopsy sections and in simultaneously obtained aspirated smears and aspirated clot sections from 251 patients. Significantly different amounts of stainable iron were observed in needle biopsy sections and aspirated smears in 15% of the specimens. The usual difference consisted of significantly less stainable iron in needle biopsy sections as compared to the aspirated smears (13%). Of clinical importance was the finding of absent stainable iron in 8% of the needle biopsy sections, in contrast to the definite deposits observed in the corresponding aspirated smear. Of similar interest was the observation that 6% of the needle biopsy sections had significantly less stainable iron than corresponding hemosiderotic smears. The amounts of stainable iron in needle biopsy sections were similar to the amounts observed in the corresponding aspirated clot sections. Evaluation of marrow iron using needle biopsy sections as well as aspirated clot sections differs from results observed in aspirated smears and could be a source of significant error in the assessment of iron stores.

Iron absorption during iron supplementation in blood donors

The total amount of iron absorbed from a total supplementation of 2000 mg of iron was studied after a blood donation. 10 regular blood donors and 10 subjects without previous blood loss were included in the study. No subject had received any iron treatment before the investigation. Both groups were given one sustained release tablet containing 100 mg of iron as Fe SO4 once daily for 20 days. The iron in these tablets was labelled with 59Fe. The total amount of iron absorbed from the tablets was measured by a whole body counting technique. Laboratory tests including haematological data, desferrioxamine tests and sternal marrow punctures were made before and after the iron treatment. The non-donors lost a mean amount of 215 mg iron by phlebotomy and the total iron absorption from the tablets was only 94 mg (4.7%). In the regular blood donors the corresponding iron loss was 276 mg and the absorption was 280 mg (14%). The iron supplementation given in this study covered the iron losses in the regular blood donors but not in the non-donors. This iron prophylaxis will present a depletion but not a reduction of the iron stores in blood donors with high donation frequency.

Significance for the diagnosis of iron overload of histochemical and chemical iron in the liver of control subjects

Storage iron was examined in surgical liver biopsy specimens in 43 haematologically normal and otherwise healthy adult individuals. These patients had no history of unphysiological iron losses nor of unphysiological iron intake. Histochemical iron was estimated in parenchymal and Kupffer cells and graded from 0 to 4+. Stainable iron of grade 1+ or more was present in parenchymal cells in 23 of the 27 men. Six of them had a 3+ grade. In nine cases iron was also visible in Kupffer cells. Visible iron was absent in most of the menstruating women. The mean total nonhaemin iron concentration for the male group was 80.2 (19.4 to 227.0), for the postmenopausal women 50.7 (19.3 to 106.6), and for the menstruating women 23.5 (5.5 to 65.9) mg./100 g. dry weight. The mean value for the women was significantly lower than the mean value for the men. There was a significant correlation between the histochemical grades of iron and chemically determined nonhaemin iron, but the degree of overlapping was considerable. The presence of stainable iron in the parenchymal liver cells is a normal finding. The significance of the present results with reference to familial studies of haemochromatosis is discussed.