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

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.

Detecting iron deficiency in anemic patients with concomitant medical problems

OBJECTIVE

To determine the sensitivity and specificity of mean corpuscular volume, transferrin saturation, total iron-binding capacity, and ferritin level in determining iron deficiency in a population of anemic veterans with a wide variety of general medical diagnoses.

DESIGN

Retrospective chart review.

SETTING

Hospitals of the Department of Veterans Affairs in Madison and Milwaukee, Wisconsin.

PARTICIPANTS

One hundred one anemic veterans with any medical condition who underwent bone marrow aspiration and serum iron studies.

MEASUREMENTS AND MAIN RESULTS

Using the presence or absence of bone marrow hemosiderin as the reference standard, the sensitivity and specificity of the following serum iron indicators were calculated: mean corpuscular volume, transferrin saturation, total iron-binding capacity, and ferritin level. Of these patients, 41 (40.6%) were categorized as iron deficient, with no stainable bone marrow hemosiderin. A serum ferritin level < or =100 microg/L provided the best sensitivity (64.9%) and specificity (96.1%) for evaluating iron stores in this patient population. When performed within 24 hours of bone marrow examination, a serum ferritin level < or =100 microg/L was 100% accurate in separating iron-deficient from iron-sufficient patients. None of the other serum iron indicators alone or in combination performed better than ferritin level alone.

CONCLUSIONS

In a population of anemic veterans with a wide variety of concomitant medical problems, a serum ferritin level < or =100 microg/L was optimal for determining iron deficiency. This is higher than the ferritin level of < or =50 microg/L cited in standard textbooks as evidence of iron deficiency in patients with inflammation, infection, or malignancy.

Laboratory diagnosis of iron-deficiency anemia: an overview

BACKGROUND AND METHODS

To determine the diagnostic values of laboratory tests used in the diagnosis of iron-deficiency anemia, the authors conducted a systematic overview of the relevant literature. Computerized searches of the MEDLINE database yielded 1,179 potentially relevant citations. Fifty-five studies included the results of laboratory tests and histologic examination of the bone marrow for at least 50% of an identifiable patient group. In these 55 studies, quality was assessed and descriptive information concerning the study populations, the tests conducted, and the results was extracted, all in duplicate.

RESULTS

Serum ferritin radioimmunoassay was by far the most powerful test, with an area under the receiver operating characteristic curve of 0.95. Test properties differed for populations of patients with inflammatory, liver, or neoplastic disease and patients without these conditions. Likelihood ratio lines, which allow precise interpretation of results across the entire range of ferritin concentration values, were constructed for the individual populations.

CONCLUSION

Serum ferritin radioimmunoassay is an extremely powerful test for the diagnosis of iron-deficiency anemia and, appropriately interpreted, can be applied to the complete range of patients.

Iron metabolism in patients with the anaemia of end-stage renal disease during treatment with recombinant human erythropoietin

Iron metabolism was studied in 21 patients with the anaemia of end-stage renal disease during 40 weeks of treatment with recombinant human erythropoietin (rhEPO). Oral iron was prescribed to all patients. Initial serum iron concentrations and transferrin saturation levels were subnormal, decreased during the correction period of treatment, and increased thereafter. In 81% of patients in whom pretreatment transferrin saturation was below 0.25, transferrin saturation decreased below 0.16, despite sufficiently high serum ferritin levels. Serum ferritin concentrations decreased significantly. There was no correlation between serum ferritin levels and serum iron or transferrin saturation. Ferrokinetic studies, performed before and during treatment, showed an increase in plasma iron turnover, in erythron transferrin uptake, and in the flux of iron binding sites through the plasma. The rhEPO dose needed to keep the haematocrit at the target level during the maintenance period of treatment was significantly correlated with transferrin saturation, and iron binding capacity, but not with serum ferritin concentrations. This suggests that the functional availability of iron in plasma, rather than the size of body iron stores, is a major factor in the determination of the response to rhEPO treatment in end-stage renal disease.

Effect of human erythropoietin derived from recombinant DNA on the anaemia of patients maintained by chronic haemodialysis

Ten patients with end-stage renal failure and anaemia (mean haemoglobin 6.1 g/dl, range 4.6-8.8 g/dl) on thrice-weekly haemodialysis were treated with human erythropoietin derived from recombinant DNA (rHuEPO). This was given as an intravenous bolus after each dialysis in rising doses within the range 3-192 IU/kg. All patients showed increases in reticulocyte numbers and haemoglobin concentration and after the first week of treatment none of the four previously transfusion-dependent patients needed further transfusions. In nine patients treated for 12 weeks haemoglobin rose to a mean of 10.3 g/dl, range 9.5 to 12.8 g/dl. Thereafter the dose of erythropoietin was adjusted to avoid a further rise in haemoglobin. During treatment one patient had an episode of hypertensive encephalopathy and two had clotting in their arteriovenous fistulas (complete in one). rHuEPO is an effective treatment for the anaemia of end-stage renal failure but longer-term observations are needed on the consequences of increasing the haematocrit.

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.