Contributions
Abstract: PB2068
Type: Publication Only
Background
Soluble transferrin receptor (sTfR) is one of the main regulators of cellular iron homeostasis, and is an emerging diagnostic tool of iron status.
Aims
To investigate the diagnostic value of sTfR as compared to serum ferritin (SF) in assessment of iron overload expressed as liver iron concentration (LIC) measured by magnetic resonance imaging (MRI) in patients with β-thalassemia major (BTM) and sickle cell disease (SCD).
Methods
Eighty transfusion dependent patients (64 BTM and 16 SCD) with a mean age of 10.8±4.5 years were recruited. Steady state SF and sTfR levels were assessed quantitatively by enzyme linked immunoassay (ELISA). LIC values, within 6 months’ duration, as identified by quantitative MRI of hepatic iron stores as a signal intensity ratio method based on T1 and T2* contrast imaging without gadolinium were retrieved. We categorized iron overload status in our patients into 2 subgroups: group A; 52 patients with LIC >7mg/g dw, and group B; 28 patients with LIC < 7mg/g dw. Informed consent was obtained from patients’ legal guardians before enrollment. The study protocol was approved by Cairo University Research Ethics Committee.
Results
Mean sTfR, SF and LIC of studied group (n=80) were 121 nmol/L, 2478 ng/ml and 18.6 mg/g dw respectively. BTM and SCD patients had comparable mean sTfR and SF (p>0.05 for both) but LIC was significantly higher in BTM group (p<0.001). Group A had significantly higher median sTfR and SF compared to group B (p = 0.026 and 0.003 respectively). However, sTfR did not correlate with SF or LIC (p=0.273, 0.725 respectively). A positive correlation was evident between SF and LIC (r=0.49, p=0.001). Both sTfR and SF were good predictors of iron overload at certain cutoff levels; ROC curve of sTfR and SF at cutoff values of 110.4 nmol/L and 1220 ng/ml respectively demonstrated a sensitivity of 90.6%, specificity 62.5% for both (p˂0.05). Using Cohen's kappa testing, agreement between serum sTfR at a level of 110.4 nmol/L and LIC was evident (p=0.001); but this significance was lost at sTfR values ≥133.3 nmol/L. Significant agreement between SF and LIC were evident at both values of 1220 ng/ml and 1591.5 ng/mL and higher (p=0.001 and 0.014 respectively).
Conclusion
sTfR was a valuable quantitative assay of iron overload in children with BTM and SCD. Both sTfR and SF could accurately predict hepatic iron overload among our patients at certain cutoff values. However, the overall accuracy and agreement of sTfR with LIC was lost at high serum values.
Session topic: 30. Iron metabolism, deficiency and overload
Keyword(s): iron overload, Sickle cell, Thalassemia
Abstract: PB2068
Type: Publication Only
Background
Soluble transferrin receptor (sTfR) is one of the main regulators of cellular iron homeostasis, and is an emerging diagnostic tool of iron status.
Aims
To investigate the diagnostic value of sTfR as compared to serum ferritin (SF) in assessment of iron overload expressed as liver iron concentration (LIC) measured by magnetic resonance imaging (MRI) in patients with β-thalassemia major (BTM) and sickle cell disease (SCD).
Methods
Eighty transfusion dependent patients (64 BTM and 16 SCD) with a mean age of 10.8±4.5 years were recruited. Steady state SF and sTfR levels were assessed quantitatively by enzyme linked immunoassay (ELISA). LIC values, within 6 months’ duration, as identified by quantitative MRI of hepatic iron stores as a signal intensity ratio method based on T1 and T2* contrast imaging without gadolinium were retrieved. We categorized iron overload status in our patients into 2 subgroups: group A; 52 patients with LIC >7mg/g dw, and group B; 28 patients with LIC < 7mg/g dw. Informed consent was obtained from patients’ legal guardians before enrollment. The study protocol was approved by Cairo University Research Ethics Committee.
Results
Mean sTfR, SF and LIC of studied group (n=80) were 121 nmol/L, 2478 ng/ml and 18.6 mg/g dw respectively. BTM and SCD patients had comparable mean sTfR and SF (p>0.05 for both) but LIC was significantly higher in BTM group (p<0.001). Group A had significantly higher median sTfR and SF compared to group B (p = 0.026 and 0.003 respectively). However, sTfR did not correlate with SF or LIC (p=0.273, 0.725 respectively). A positive correlation was evident between SF and LIC (r=0.49, p=0.001). Both sTfR and SF were good predictors of iron overload at certain cutoff levels; ROC curve of sTfR and SF at cutoff values of 110.4 nmol/L and 1220 ng/ml respectively demonstrated a sensitivity of 90.6%, specificity 62.5% for both (p˂0.05). Using Cohen's kappa testing, agreement between serum sTfR at a level of 110.4 nmol/L and LIC was evident (p=0.001); but this significance was lost at sTfR values ≥133.3 nmol/L. Significant agreement between SF and LIC were evident at both values of 1220 ng/ml and 1591.5 ng/mL and higher (p=0.001 and 0.014 respectively).
Conclusion
sTfR was a valuable quantitative assay of iron overload in children with BTM and SCD. Both sTfR and SF could accurately predict hepatic iron overload among our patients at certain cutoff values. However, the overall accuracy and agreement of sTfR with LIC was lost at high serum values.
Session topic: 30. Iron metabolism, deficiency and overload
Keyword(s): iron overload, Sickle cell, Thalassemia