Soluble transferrin receptor levels and soluble transferrin receptor/log ferritin index in the evaluation of erythropoietic status in childhood infections and malignancy.
Soluble transferrin receptor (sTfR) is a new diagnostic tool for determining iron status and erythropoietic activity. The increased concentrations of sTfR in patients with iron deficiency reflect the hyperplasia of erythroid precursors. The objective of this study was to evaluate sTfR and sTfR/log ferritin index (sTfR-F) values in healthy children (n = 64), full-term neonates (n = 18), children with iron deficiency (n = 16), hemolytic anemia (n = 7), beta-thalassemia traits (n = 18), respiratory infections (n = 41) and malignancies (n = 13), and to compare these parameters for the different subgroups with those of healthy children. The sTfR levels were increased in children with iron deficiency in the same way as in adults (p < 0.0001) and in cases of increased erythropoietic activity, such as during the neonatal period (p < 0.0001), and of hemolytic anemias (p = 0.006). The index was significantly increased in iron deficiency (p < 0.0001) and decreased in neonates (p = 0.011). Children carriers of beta-thalassemia were found to have increased sTfR values (p = 0.015), but not sTfR/log ferritin index (p = 0.491), a finding suggesting that use of both parameters is necessary for distinguishing between those with and those without iron deficiency. In children with upper respiratory infection, the sTfR levels were close to normal, while the index was found to be low. In order to evaluate the iron status in infections, we further subdivided the children into two groups according to the value of ferritin, with the cut-off point at 35 microg/L. Children with ferritin level above 35 microg/L experienced normal sTfR levels but very low index, a finding which could enable the use of these two parameters for distinguishing patients with infection without concomitant iron deficiency. In the group of malignancies under chemotherapy both indices were low (p = 0.005, p < 0.0001) mainly due to myelosuppression.


CONCLUSIONS
The interpretation of both sTfR and sTfR/log ferritin index is useful in the evaluation of iron status and erythropoietic activity, especially in children with heterozygous beta-thalassemia, infection and malignancies.
Dimitriou
H
H
Department of Pediatric Hematology/Oncology, University Hospital of Heraklion, Crete, Greece.
Stiakaki
E
E
Markaki
E A
EA
Bolonaki
I
I
Giannakopoulou
C
C
Kalmanti
M
M
D000293:Adolescent; D000743:Anemia, Hemolytic / Q000097:blood; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004920:Erythropoiesis; D005260:Female; D005293:Ferritins / Q000097:blood*; D006579:Heterozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007501:Iron / Q000097:blood*; D000090463:Iron Deficiencies; D008297:Male; D009369:Neoplasms / Q000097:blood*; D011990:Receptors, Transferrin / Q000097:blood*; D012141:Respiratory Tract Infections / Q000097:blood*; D012995:Solubility; D017086:beta-Thalassemia / Q000097:blood
D015415:Biomarkers; D011990:Receptors, Transferrin; D005293:Ferritins; D007501:Iron