Evaluation of a packaged kit assay of serum ferritin and application to clinical diagnosis of selected anemias

Anemia of malignancy

Anemia is a common association of malignant disease. It may be the first diagnostic clue to an underlying malignant disease, it may contribute to the patient's symptoms from the disease, and it may affect treatment decisions. It is important to recognize that a number of underlying mechanisms may contribute to the anemia, and to exclude those that are treatable. The recognition that tumor-associated cytokine production is a major factor in the anemia of malignancy, and that recombinant EPO can overcome this suppression, are major steps forward.

Extremely elevated serum ferritin levels in a university hospital: associated diseases and clinical significance

PURPOSE

To establish the frequency with which serum ferritin levels > or = 1,000 ng/mL occur in a general hospital population, and to determine the clinical significance of this finding.

PATIENTS AND METHODS

All serum ferritin determinations performed between June 1992 and July 1993 at the University of Cincinnati Medical Center were reviewed and patients with serum ferritin levels > or = 1,000 ng/mL identified. The medical records of these patients were then reviewed.

RESULTS

Of 1,826 serum ferritin determinations performed during the study period, 122 (6.7%) were > or = 1,000 ng/mL. Associated clinical syndromes found in the 95 patients with serum ferritin > or = 1,000 ng/mL included liver disease (20.0%), renal disease (17.9%), malignant disease (17.9%), human immunodeficiency virus (HIV) infection (16.8%), non-HIV systemic infections (15.8%), chronic transfusions (10.5%), and sickle cell syndromes (10.5%). No syndrome usually associated with extreme serum ferritin elevations was identified in 8.4% of patients, and 16.8% of the patients fell into more than one category. The highest mean serum ferritin levels occurred in the chronically transfused and sickle cell groups. Concomitant serum transferrin saturation values were determined with 82 (86.3%) of the elevated serum ferritin levels and did not correlate well with them. The highest mean transferrin saturation levels occurred in the liver disease group. Transferrin saturation > or = 50%, suggestive of iron overload, was significantly more frequent in the liver disease group (P = 0.002); and saturation < or = 15%, suggestive of iron-deficient erythropoiesis, was significantly more frequent in the HIV group (P = 0.001).

CONCLUSION

Outside the setting of clinical syndromes associated with iron overload (liver disease, transfusions, sickle cell syndromes), serum ferritin levels > or = 1,000 ng/mL serve as a nonspecific marker for a variety of significant disorders, including infectious and neoplastic diseases. Further study of the regulation of ferritin production may provide insight into the pathogenesis of disorders associated with extreme serum ferritin elevations.

Evaluation of bone marrow iron stores in anemia associated with chronic disease: a comparative study of serum and red cell ferritin

The serum ferritin (SERFER) may be elevated and misleading in the setting of chronic disease (chronic inflammation, liver disease, and neoplasm). The red cell ferritin (RBCFER) may be more stable in clinical situations that affect the SERFER. We compared the ability of SERFER and RBCFER to assess iron stores in these settings. Iron stores were defined by bone marrow aspirate staining. We studied 120 anemic (Hb < 14 g/dl) male patients. Twenty-eight (23%) were iron deficient based on the absence of marrow iron. The SERFER correlation with marrow iron stores (r = 0.58; P < 0.001) was better than the RBCFER (r = 0.36; P < 0.001). Cutoff values for the diagnosis of iron deficiency were determined by chi-square analysis (SERFER < 70 ng/ml; RBCFER < or = 4 ag/RBC). The sensitivity for detecting iron deficiency with SERFER (0.60) was less than RBCFER (0.82). The specificity of SERFER (0.90) was slightly better than RBCFER (0.83). Neither difference reached statistical significance (P > 0.05). The positive predictive value between the two assays was the same (SERFER 0.65 vs. RBCFER 0.59). The combination of SERFER < 70 ng/ml with RBCFER < or = 4 ag/RBC was more specific (0.97) when compared with the SERFER alone (0.90) (P = 0.04). In addition, the potential of this combination to predict iron deficiency (0.82) was higher than that seen with either SERFER (0.65) or the RBCFER (0.59). Our findings show that the RBCFER as a single assay is not anymore accurate than the SERFER. However, we find that the RBCFER can effectively complement the SERFER to either predict iron depletion or confirm the presence of bone marrow iron.

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.

Diagnosis of iron-deficiency anemia in the elderly

PURPOSE

To determine the value of serum ferritin, mean cell volume, transferrin saturation, and free erythrocyte protoporphyrin in the diagnosis of iron-deficiency anemia in the elderly.

PATIENTS AND METHODS

We prospectively studied consecutive eligible and consenting anemic patients over the age of 65 years, who underwent blood tests and bone marrow aspiration. The study consisted of 259 inpatients and outpatients at two community hospitals in whom a complete blood count processed by the hospital laboratory demonstrated previously undiagnosed anemia (men: hemoglobin level less than 12 g/dL; women: hemoglobin level less than 11.0 g/dL).

RESULTS

Thirty-six percent of our patients had no demonstrable marrow iron and were classified as being iron-deficient. The serum ferritin was the best test for distinguishing those with iron deficiency from those who were not iron-deficient. No other test added clinically important information. The likelihood ratios associated with the serum ferritin level were as follows: greater than 100 micrograms/L, 0.13; greater than 45 micrograms/L but less than or equal to 100 micrograms/L, 0.46; greater than 18 micrograms/L but less than or equal to 45 micrograms/L, 3.12; and less than or equal to 18 micrograms/L, 41.47. These results indicate that values up to 45 micrograms/L increase the likelihood of iron deficiency, whereas values over 45 micrograms/L decrease the likelihood of iron deficiency. Seventy-two percent of those who were not iron-deficient had serum ferritin values greater than 100 micrograms/L, and in populations with a prevalence of iron deficiency of less than 40%, values of greater than 100 micrograms/L reduce the probability of iron deficiency to under 10%. Fifty-five percent of the iron-deficient patients had serum ferritin values of less than 18 micrograms/L, and in populations with a prevalence of iron deficiency of greater than 20%, values of less than 18 micrograms/L increase the probability of iron deficiency to over 95%.

Body iron status in critically ill patients: significance of serum ferritin

Serial measurements of blood haemoglobin, serum iron, serum transferrin, total iron-binding capacity, transferrin per cent saturation and serum ferritin were determined in 51 post-operative critically ill patients to investigate body iron status in severely stressed patients. The results showed decreased blood haemoglobin, serum iron, serum transferrin and transferrin saturation compared to an increase in serum ferritin levels. These results indicate that there is inadequate availability of iron to tissues (secondary to rearrangement of body iron to the advantage of the iron storage compartment), which is often present in severely critically ill patients. A positive correlation was found between the initial (ferritin) levels and SAPS (r = 0.41, p less than 0.01). In addition, the increase of ferritin concentration parallels a worsening of the clinical status in severely ill patients. This is due to enhanced release by the macrophage system. From this, we consider serum ferritin as an acute-phase protein and a useful marker of the severity of the clinical status. It appears to be useful in predicting the patient's outcome, but is not reliable in evaluating iron stores in stressed patients.

[Serum ferritin in differential diagnosis of anemia (author's transl)]

The concentration of ferritin in the serum of normal males (n = 79) was 98 micrograms/l (geometric mean) with a 95% confidence range of 21-447 micrograms/l. In non-menstruating healthy females (n = 39), the concentration was 85 (26-279) micrograms/l. In menstruating females, serum ferritin was less than 30 micrograms/l only when the duration of menstruation was more than or equal to 4 days. Patients with uncomplicated iron-deficiency anemia had a serum ferritin level less than 20 micrograms/l. After oral or parenteral iron therapy, serum ferritin was greater than 20 micrograms/l in 7 to 17 patients. Serum ferritin was greater than 20 micrograms/l in 8 of 12 patients with a simultaneous inflammatory or malignant disease. Of patients with iron-deficiency anemia, 86% had a serum ferritin level lower than 40 micrograms/l. A serum ferritin level less than 40 micrograms/l was only observed in patients with iron-deficiency anemia and not in patients with other forms of anemia. Of patients with iron-deficiency anemia and a hemoglobin concentration lower than 100 g/l, 80% had a serum iron level less than 13 mumol/l and a total iron binding capacity higher than 70 mumol/l. Anemia of chronic disorders was diagnosed with a sensitivity of 0.93 and a specificity of 0.92 in patients with serum iron less than 13 mumol/l, total iron binding capacity less than 60 mumol/l, erythrocyte sedimentation rate greater than 25 mm in the first hour, and serum fibrinogen greater than 4 g/l. Somewhat better was the same combination except with the serum ferritin level greater than 50 micrograms/l instead of the iron binding capacity. However the predictive value using both combinations was too low.

The laboratory evaluation of microcytic red blood cells

Microcytic red blood cell states are common clinical problems in both adult and pediatric age groups. The recent widespread availability of electronic blood cell counters for performing routine blood counts has increased the detection of microcytic red blood cells. Physicians must workup both symptomatic and asymptomatic patients with microcytic red blood cells before they can initiate proper therapy and/or counseling. The purpose of this review is threefold: (1) to discuss the causes of microcytic red blood cells in terms of disorders of decreased heme production vs. disorders of decreased globin production, (2) to review the clinical laboratory tests useful in differentiating microcytic red blood cell states, and (3) to present a practical approach for the laboratory workup of microcytic red blood cells.

Regulation of iron therapy by S-ferritin estimations in patients on chronic hemodialysis

Serum ferritin estimation was compared with bone marrow hemosiderin staining in the primary diagnosis of iron deficiency and overload in 19 patients on chronic hemodialysis. Serum ferritin estimation had a high predictive value: all 8 patients with marrow iron grade III had elevated S-ferritin values, and 3 out of 5 iron-deficient patients had subnormal values, the other 2 low-normal values. Serum iron and transferrin estimation was of very little value. Prophylactic treatment with 100 mg iron sulphate daily p.o. was inadequate for 13 of the 19 patients: 8 had iron overload. 5 had iron deficiency. Iron sulphate therapy was monitored by bone marrow hemosiderin and serum ferritin values and 15 patients could be followed up for one year. It was shown that serum ferritin estimations could be used to monitor the iron therapy.

Serum ferritin in the regulation of iron therapy in blood donors

12 regular blood donors were selected on the basis of subnormal serum ferritin levels as a criterion for iron deficiency. It was found that all had high transferrin levels but only 5 had subnormal serum iron or transferrin saturation. The donors were given oral iron therapy in a dose of 2,800 mg between each phlebotomy, and the donation interval was standardized to 8 weeks. Test samples were collected every 4th week. After an initial rise in ferritin during the first 2 months, 6 of the donors again had subnormal serum ferritin levels, and the iron dose was therefore doubled after 32 weeks. Following this, all subjects taking the higher dose had normal ferritin values and stainable marrow iron was found at the end of the study, after 92 weeks. 3 subjects did not take the higher dose, had no raised serum ferritin level or stainable hemosiderin. It is concluded that serum ferritin estimation can be used to monitor the therapy in blood donors so that a satisfactory amount of iron is stored.