[Serum transferrin receptor in healthy children. Diagnostic yield in ferropenic and infectious anemia].
BACKGROUND
The serum transferrin receptor (TfR) presents certain advantages over other parameters of cellular iron status because it does not vary in acute or chronic diseases.


OBJECTIVE
To establish reference ranges of TfR in healthy children for our laboratory, to define the distribution of this variable in children with acute illness and in those with iron deficiency, and to evaluate the diagnostic yield of TfR, the transferrin-receptor/ferritin ratio (TfR/F) and the transferrin-receptor-ferritin index (TfR-F) in distinguishing ferropenic from infectious anemia.


METHODS
A descriptive, cross-sectional analysis was conducted in 132 children aged from 6 months to 16 years for a period of 18 months. The subjects were classified in three groups: healthy children, children with acute illness, and children with iron deficiency. The distribution of TfR and its diagnostic yield were evaluated.


RESULTS
Of the 132 subjects, 30 were excluded because they lacked one or more of the parameters under analysis and 19 were excluded because they showed a thalassemic trait. In the 30 healthy children, the mean TfR concentration was 1.2 mg/l (SD 0.36) and the median was 1.02 (IQR 0.7-1.7). In the 32 children with acute illness, with or without anemia, TfR values were similar to those found in healthy children (p > 0.05). TfR values were higher in children with iron deficiency (21 patients; mean TfR value: 1.67 mg/l SD 0:98) than in healthy children but this difference was not statistically significant (p 0.08). The highest TfR values were found in the group with ferropenic anemia (mean TfR value: 2.13 mg/l SD 1.14) with a statistically significant difference between healthy children (p 0.04) and those with iron deficiency without anemia (p 0.01). The TfR/F ratio showed an optimal diagnostic yield in distinguishing ferropenic from acute disease anemia. If this ratio is higher than 80.7 ferropenia can be suspected as the cause of the anemia with a global value of the test of 100 % (95 % CI: 75.91-99.42).


CONCLUSIONS
TfR could be useful in evaluating intracellular iron status in children. Acute disease does not alter TfR values and, in combination with ferritin, TfR offers an optimal diagnostical yield in distinguishing ferropenic from acute illness anemia.
Aleo Luján
E
E
Servicio de Pediatría (6.a planta), Hospital Clínico San Carlos, Prof. Martín Lagos s/n, 28045 Madrid, Spain. estheraleo@yahoo.com
Gil López
C
C
González Fernández
F A
FA
Villegas Martínez
A
A
Valverde Moreno
F
F
D000208:Acute Disease; D000293:Adolescent; D018798:Anemia, Iron-Deficiency / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D003141:Communicable Diseases / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011990:Receptors, Transferrin / Q000097:blood*; D012016:Reference Values
D011990:Receptors, Transferrin