Hepatic iron stores and plasma ferritin concentration in patients with sickle cell anemia and thalassemia major

Sickle cell disease

The identification of genetic mutation that causes sickle cell disease 35 years ago has not yet led to a widely applicable, specific therapy that corrects the underlying abnormality of hemoglobin. Nevertheless, recent progress in understanding the pathophysiology and natural history of sickling disorders has led directly to important prophylactic and supportive therapies that have markedly reduced morbidity and prolonged life expectancy. This is particularly true for manifestations of sickle cell disease that result from damage to the spleen, lungs, and brain. New strategies for specific therapy, including expanded use of chronic transfusions, bone marrow transplantation, and hydroxyurea, now offer hope for prevention of many or all of the hemolytic and vaso-occlusive manifestations of sickle cell disease.

Liver iron stores in patients with secondary haemosiderosis under iron chelation therapy with deferoxamine or deferiprone

Total body iron stores including liver and spleen iron were assessed by non-invasive SQUID biomagnetometry. The liver iron concentration was measured in groups of patients with beta-thalassaemia major or other posttransfusional siderosis under treatment with the oral iron chelator deferiprone (n = 19) and/or with parenteral deferoxamine (n = 33). An interquartile range for liver iron concentrations of 1680-4470 micrograms/g liver was found in these patients. In both groups a poor correlation between liver iron and serum ferritin values was observed. Repeated measurements of liver and spleen iron concentrations as well as determination of liver and spleen volume by sonography were performed in six patients under continuous deferiprone treatment for 3-15 months. In this group detailed information was obtained on the whole body iron store (5-36g) and the iron excretion rates (14-34 mg/d) for each patient. As indicated by decreasing liver iron concentrations, five out of six subjects showed a negative iron balance (2-13 mg/d). Conventional measurements of both serum ferritin and urine iron excretion gave fluctuating results, thus being only of limited use in the control of iron depletion therapy. The non-invasive biomagnetic liver iron quantification is a precise and clinically verified technique which offers more direct information on the long-term efficacy of an iron depletion therapy than the hitherto used methods. This technique may be of use in the clinical evaluation of new oral iron chelators.

Uneven hepatic iron and phosphorus distribution in beta-thalassemia

BACKGROUND/AIMS

Determination of hepatic iron concentration is crucial in the evaluation of iron-storage disease. Iron content is normally determined in a part of a needle liver biopsy and the value obtained is considered to be representative of the iron concentration in the whole liver. To evaluate the reliability of this procedure, we studied iron distribution in the liver of two beta-thalassemic patients. Since the transport of intracellular iron is mediated by phosphates, we also studied the hepatic phosphorus distribution.

METHODS

At autopsy, a liver slice extending from the left to the right lobe was divided into 51 and 49 samples, respectively. Each specimen was subdivided into two parts: one of them was paraffin-embedded and utilized for the histochemical detection of iron; the second part was analyzed for iron and phosphorus content by induced coupled plasma atomic emission spectroscopy.

RESULTS

The histological picture of both livers was characterized by portal and periportal fibrosis associated with iron storage of different degree, without cirrhosis. The mean iron concentration of the liver was 20,631 +/- 4903 micrograms per g of dry tissue (micrograms/g dt) and 13,901 +/- 1976 micrograms/g dt, respectively. A striking variability in iron content between samples was also found: iron concentration ranged from 11,537 to 32,347 micrograms/g dt in the first case and from 6257 to 16,493 in the second case. We even observed regional differences in iron concentration, with a preferential peripheral accumulation in both cases and a tendency of the left compartment of the liver to accumulate more iron in the first case. Histochemical analyses confirmed the uneven iron distribution even at the acinar level, showing iron mainly being stored in hepatocytes and Kupffer cells of zone 1 of the acinus, with decreasing amounts of iron in zones 2 and 3. The mean hepatic phosphorus concentration was 6662 +/- 1300 micrograms/g dt (range: 4348-9947) and 7502 +/- 986 micrograms/g dt (range: 5844-90,282), respectively. The regional distribution of phosphorus was similar to that observed for iron. A strict correlation between iron and phosphorus content was also observed.

CONCLUSIONS

Our data show that: 1) iron and phosphorus are unevenly distributed in the beta-thalassemic liver, even in the non-cirrhotic stages; 2) a regional pattern of iron and phosphorus distribution is evident, characterized by higher concentrations at the periphery of the liver; 3) the observed uneven distribution of iron and phosphorus implies that their content determined in a small liver sample cannot be considered as absolutely representative of the mean hepatic iron concentration. Therefore, iron concentrations determined in a part of a needle liver biopsy should be interpreted with caution in monitoring the efficacy of the iron-chelating therapy in beta-thalassemic patients.

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.

Iron-chelation therapy with oral deferiprone in patients with thalassemia major

BACKGROUND

To determine whether the orally active iron chelator deferiprone (1,2-dimethyl-3-hydroxy-pyridin-4-one) is efficacious in the treatment of iron overload in patients with thalassemia major, we conducted a prospective trial of deferiprone in 21 patients unable or unwilling to use standard chelation therapy with parenteral deferoxamine.

METHODS

Hepatic iron stores were determined yearly by chemical analysis of liver-biopsy specimens or magnetic-susceptibility measurements. Detailed clinical and laboratory studies were used to monitor safety and compliance.

RESULTS

The patients received deferiprone therapy for a mean (+/-SE) of 3.1 +/- 0.3 years. Ten patients in whom previous chelation therapy with deferoxamine had been ineffective had initial hepatic iron concentrations of at least 80 mumol per gram of liver, wet weight -- values associated with complications of iron overload. Hepatic iron concentrations decreased in all 10 patients, from 125.3 +/- 11.5 to 60.3 +/- 9.6 mumol per gram (P < 0.005), with values that were less than 80 mumol per gram in 8 of the 10 patients (P < 0.005). In all 11 patients in whom deferoxamine therapy had previously been effective, deferiprone maintained hepatic iron concentrations below 80 mumol of iron per gram.

CONCLUSIONS

Oral deferiprone induces sustained decreases in body iron to concentrations compatible with the avoidance of complications from iron overload. The risk of agranulocytosis associated with deferiprone may restrict its administration to patients who are unable or unwilling to use deferoxamine.

Needle liver biopsy in thalassaemia: analyses of diagnostic accuracy and safety in 1184 consecutive biopsies

We report the reliability and safety of percutaneous liver biopsy in the evaluation of hepatic iron loading and histology in patients with homozygous beta-thalassaemia prior to and in serial biopsies following allogeneic bone marrow transplantation for this disorder. 501 thalassaemic patients aged 11 +/- 4.5 years (range 1-32 years) underwent 1184 consecutive percutaneous liver biopsies without ultrasound guidance. Overall, 81% of biopsies were evaluable for histological examination and grading of iron. The adequacy of liver biopsy specimens increased with patient age: evaluable specimens were obtained in 73% of patients < 5 years of age and in 86% of samples in patients aged > 15 years. The degree of iron overload and fibrosis in each biopsy was reported separately by at least two pathologists who did not know the clinical status of each patient. In 103 biopsies, iron grade by light microscopy corresponded to an iron concentration varying between a mean of 32.46 +/- 14 mumol/g dry weight liver tissue for iron stores graded by light microscopy as absent to 417.6 +/- 150 mumol/g dry weight liver tissue for stores graded as severe. The fibrosis score of multiple samples of liver obtained at autopsy within 100 d of the percutaneous biopsy in 41 patients who died following BMT correlated perfectly with that of the first sample in > 60% biopsies; in most of the discordant cases fibrosis had been underestimated in the percutaneous biopsy. Liver biopsy demonstrated evidence of chronic hepatitis in 30% of patients with normal transaminase and in 57% of patients with transaminase within twice the normal range. Liver biopsy was complicated in six patients (0.5%) by haemoperitoneum, periocholecystic haematoma, kidney haematoma, or bile peritonitis; no complication was fatal. These data demonstrate that percutaneous liver biopsy provides reliable information regarding liver iron and histology in homozygous beta-thalassaemia with an extremely low risk of complications.

Assessment of liver iron overload by T2-quantitative magnetic resonance imaging: correlation of T2-QMRI measurements with serum ferritin concentration and histologic grading of siderosis

PURPOSE

To correlate hepatic 1/T2 values obtained by means of a T2-Quantitative MRI (T2-QMRI) technique with three widely applied methods for the evaluation of hemosiderosis, i.e., (a) liver iron concentrations (LFeC) (b) serum ferritin (SF), and (c) histologic grading of siderosis. The impact of coexisting hepatitis was also considered. T2-QMRI measurements were compared with signal intensity (SI) ratio measurements on conventional SE images.

MATERIALS AND METHODS

Liver T2 relaxation times were calculated in 40 thalassemic patients, on a 0.5 T magnetic resonance imaging system using a multiple spin-echo sequence with parameters: TR = 2500 ms, TE = 12 ms in 20 symmetrically repeatable echoes.

RESULTS

(a) 1/T2 values were well correlated (r = 0.97) with liver iron concentrations, which ranged from 2.32 to 18.0 mg/g dry weight (normal < 1.6 mg/g). (b) 1/T2 values were also correlated with serum ferritin levels (r = 0.84). At various 1/T2 values, serum ferritin levels were higher for the anti-HCV(+) patients than the anti-HCV(-) ones. (c) T2 values corresponding to successive grades of siderosis presented statistically significant differences. (d) SI ratio measurement assigned less statistically significant results, as compared to T2 values.

CONCLUSION

T2-QMRI measurement of T2 relaxation time is more accurate than SI ratios in evaluating liver iron overload. It is particularly useful for hemosiderotic patients with coexisting hepatitis since, in this case, serum ferritin is not considered a reliable index of hemosiderosis.

Clinical manifestations and therapy of transfusional haemosiderosis

Long-term blood transfusions lead to the accumulation of iron that in the absence of chelation therapy causes complications such as liver cirrhosis, growth failure, hypogonadism, hypothyroidism, hypoparathyroidism, diabetes and myocardiopathy. The last still represents the most frequent cause of death in haemosiderotic transfusion-dependent patients. At the moment the only chelator widely used is desferrioxamine (DFX). The drug works best when administered as a continuous infusion, mainly by the subcutaneous route. To patients with severe iron overload, impending organ failure, or poor compliance to chelation, DFX can be administered intravenously, through an externalized central catheter or, preferably, a subcutaneous port. Several studies have shown the effectiveness of DFX in reducing the iron burden, thus preventing the complications, once considered inevitable, of iron overload, and even in reverting some, but not all, of the iron-induced dysfunctions. Practical and psychological support are necessary to ensure satisfactory compliance with a therapy that is cumbersome and difficult. Toxic effects of DFX such as growth failure, hearing impairment and bone abnormalities seem to occur mainly in patients who have received high doses of DFX despite a low iron burden. Visual loss and renal and pulmonary toxicities, on the contrary, seem to be more directly related to high DFX peak doses administered irrespective of the patient's amount of iron overload. After bone marrow transplantation, phlebotomy or erythrocytoapheresis might be necessary to reduce further the iron accumulated during years of transfusions.

Efficacy of deferoxamine in preventing complications of iron overload in patients with thalassemia major

BACKGROUND

To determine whether deferoxamine prevents the complications of transfusional iron overload in thalassemia major, we evaluated 59 patients (30 were female and 29 male; age range, 7 to 31 years) periodically for 4 to 10 years or until death.

METHODS

At each follow-up visit, we performed a detailed clinical and laboratory evaluation and measured hepatic iron stores with a noninvasive magnetic device.

RESULTS

The body iron burden as assessed by magnetic measurement of hepatic iron stores was closely correlated (R = 0.89, P < 0.001) with the ratio of cumulative transfusional iron load to cumulative deferoxamine use (expressed in millimoles of iron per kilogram of body weight, in relation to grams of deferoxamine per kilogram, transformed into the natural logarithm). Each increase of one unit in the natural logarithm of the ratio (transfusional iron load to deferoxamine use) was associated with an increased risk of impaired glucose tolerance (relative risk, 19.3; 95 percent confidence interval, 4.8 to 77.4), diabetes mellitus (relative risk, 9.2; 95 percent confidence interval, 1.8 to 47.7), cardiac disease (relative risk, 9.9; 95 percent confidence interval, 1.9 to 51.2), and death (relative risk, 12.6; 95 percent confidence interval, 2.4 to 65.4). All nine deaths during the study occurred among the 23 patients who had begun chelation therapy later and used less deferoxamine in relation to their transfusional iron load (P < 0.001).

CONCLUSIONS

The early use of deferoxamine in an amount proportional to the transfusional iron load reduces the body iron burden and helps protect against diabetes mellitus, cardiac disease, and early death in patients with thalassemia major.

Survival in medically treated patients with homozygous beta-thalassemia

BACKGROUND

The prognosis of patients with homozygous beta-thalassemia (thalassemia major) has been improved by transfusion and iron-chelation therapy. We analyzed outcome and prognostic factors among patients receiving transfusions and chelation therapy who had reached the age at which iron-induced cardiac disease, the most common cause of death, usually occurs.

METHODS

Using the duration of life without the need for either inotropic or antiarrhythmic drugs as a measure of survival without cardiac disease, we studied 97 patients born before 1976 who were treated with regular transfusions and chelation therapy. We used Cox proportional-hazards analysis to assess the effect of prognostic factors and life-table analysis to estimate freedom from cardiac disease over time.

RESULTS

Of the 97 patients, 59 (61 percent) had no cardiac disease; 36 (37 percent) had cardiac disease, and 18 of them had died. Univariate analysis demonstrated that factors affecting cardiac disease-free survival were age at the start of chelation therapy (P < 0.001), the natural log of the serum ferritin concentration before chelation therapy began (P = 0.01), the mean ferritin concentration (P < 0.001), and the proportion of ferritin measurements exceeding 2500 ng per milliliter (P < 0.001). With stepwise Cox modeling, only the proportion of ferritin measurements exceeding 2500 ng per milliliter affected cardiac disease-free survival (P < 0.001). Patients in whom less than 33 percent of the serum ferritin values exceeded 2500 ng per milliliter had estimated rates of survival without cardiac disease of 100 percent after 10 years of chelation therapy and 91 percent after 15 years.

CONCLUSIONS

The prognosis for survival without cardiac disease is excellent for patients with thalassemia major who receive regular transfusions and whose serum ferritin concentrations remain below 2500 ng per milliliter with chelation therapy.

Fate of iron stores in thalassaemia after bone-marrow transplantation

After successful bone-marrow transplantation (BMT) in thalassaemia, the individual acquires the pattern of globin synthesis of the donor. We call such an individual "ex-thalassaemic after BMT", a term that underscores the cure of the genetic defect but maintenance of residual signs of organ damage due to iron overload and dysfunction acquired during the pretransplant years. We have analysed the extent and fate of tissue iron overload in 151 ex-thalassaemic patients after BMT, according to the risk factors of hepatomegaly, hepatic portal fibrosis, and inadequate chelation therapy. Serum ferritin concentrations decreased and unbound iron binding capacity (UIBC) increased slowly during the years after the transplant. When analysed according to risk group (assigned at the time of the transplant), ferritin and UIBC returned within the normal ranges in only the low-risk group (without hepatomegaly or portal fibrosis, and with adequate chelation pre-BMT). Ferritin and UIBC were still abnormal 7 years after the transplant in the moderate-risk group (those with one or two risk factors) and highly abnormal in the high-risk group (all three risk factors) indicating persistence of, respectively, moderate and severe iron overload at the time of transplant. In ex-thalassaemic patients who were studied before and yearly after the transplant the extent of haemosiderosis, as judged by staining of liver biopsy samples, decreased during the years after transplant. The degree of iron deposition and rate of post-BMT linear growth seem to influence rate of post-BMT decrease in tissue iron overload in different risk groups at the time of BMT.