Soluble transferrin receptor levels and soluble transferrin receptor/log ferritin index in the evaluation of erythropoietic status in childhood infections and malignancy

Serum prohepcidin levels in children with solid tumors, inflammatory bowel disease and iron deficiency anemia

BACKGROUND

Prohepcidin is one of the regulators of iron metabolism. Few studies examined its relation with solid tumors (ST), inflammatory bowel disease (IBD) and iron deficiency anemia (IDA) in children.

METHODS

We measured serum prohepcidin (SP), soluble transferrin receptor (sTfR), serum ferritin (SF), serum iron (SI), transferrin saturation (TS), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels in ST (n = 16), IBD (n = 15), IDA (n = 14) and controls (n = 18).

RESULTS

The mean SP was significantly higher in ST and IBD than in IDA and controls. SP was significantly correlated with SF in ST, IBD and ESR for IBD and CRP for ST and hemoglobin for ST.

CONCLUSION

Elevated SP may be a clinically important predictor of inflammation and leads to anemia by impairing iron utilization in IBD and ST. SP decreases in IDA and is correlated with TS but not with SF or sTfR.

Characterization and differentiation of iron status in anemic very low birth weight infants using a diagnostic nomogram

BACKGROUND

In the early weeks of life, very low birth weight (VLBW) infants experience intense laboratory blood sampling leading to clinically significant anemia and the need for red blood cell transfusion. Although controversial, treatment with recombinant human erythropoietin (EPO) and iron has been recommended to stimulate erythropoiesis; optimal dosing of EPO and iron is still uncertain.

OBJECTIVES

To assess the validity of a four-quadrant diagnostic plot of iron availability (ferritin index) versus iron demand for erythropoiesis (reticulocyte hemoglobin content, CHr) for differentiating iron status in anemic VLBW infants.

METHODS

Study subjects were enrolled in a previously reported randomized controlled trial of clinically stable VLBW infants <31 weeks' gestation and <1,300 g at birth to receive 18 days of treatment with: group 1: oral iron; group 2: EPO + oral iron, and group 3: EPO + intravenous + oral iron.

RESULTS

At the end of treatment the ferritin index was significantly higher in both EPO groups compared to the control group. By day 18, CHr of the control group declined into the quadrant of the diagnostic plot characteristic of functional iron deficiency and anemia of chronic disease. Both EPO groups ended in the quadrants that are characteristic for latent iron deficiency and iron deficiency anemia, respectively.

CONCLUSIONS

The diagnostic plot for differentiating anemia in VLBW infants may be an informative, clinically useful tool for iron status assessment under different physiologic and therapeutic erythropoietic states. Larger additional studies in difficult patient populations are needed before the clinical utility of this diagnostic procedure can be unequivocally confirmed.

Soluble transferrin receptor in Aboriginal children with a high prevalence of iron deficiency and infection

OBJECTIVES

Aboriginal children in tropical Australia have a high prevalence of both iron deficiency and acute infections, making it difficult to differentiate their relative contributions to anaemia. The aims of this study were to compare soluble transferrin receptor with ferritin in iron deficiency anaemia (IDA), and to examine how best to distinguish the effect of iron deficiency from infection on anaemia.

METHODS

We conducted a prospective study of 228 admissions to Royal Darwin Hospital in children from 6 to 60 months of age. Transferrin receptor concentrations were measured by a particle-enhanced immunoturbidimetric assay and ferritin by a microparticle enzyme immunoassay.

RESULTS

On multiple regression, the best explanatory variables for haemoglobin differences (r2=33.7%, P<0.001) were mean corpuscular volume (MCV), red cell distribution width (RDW) and C-reactive protein (CRP); whereas transferrin receptor and ferritin were not significant (P>0.4). Using > or =2 abnormal indices (MCV, RDW, blood film)+haemoglobin <110 g/l as the reference standard for IDA, transferrin receptor produced a higher area under the curve on receiver operating characteristic curve analysis than ferritin (0.79 vs. 0.64, P<0.001) or the transferrin receptor-ferritin index (0.77). On logistic regression, the effect of acute infection (CRP) on haemoglobin was significant (P<0.001) at cut-offs of 105 and 110 g/l, but not at 100 g/l when only iron deficiency indicators (MCV, RDW, blood film) were significant.

CONCLUSIONS

Transferrin receptor does not significantly improve the diagnosis of anaemia (iron deficiency vs. infection) over full blood count and CRP, but in settings with a high burden of infectious diseases and iron deficiency, it is a more reliable adjunctive measure of iron status than ferritin.