[Free erythrocyte protoporphyrin as a function of age in growing rats].

The assessment of the iron (Fe) status is very important because its deficiency is one of the most common in both developing and industrialized countries, being particularly prevalent among infants and young children. Diagnosis is difficult in the presence of other conditions which interfere with the interpretation of laboratory tests, such as hemoglobin (Hb), hematocrit (Hct), serum iron, transferrin saturation percentage and serum ferritin. Free erythrocyte protoporphyrin (FEP) is a precursor of Heme and normally occurs in very low concentration in red blood cells (RBC); elevated values indicate early impaired iron nutritional status, providing information about gradual changes in the iron supply to the marrow. This laboratory test is a practical and convenient method because it needs a small blood sample easily preserved. Although the Second National Health and Nutritional Examination Survey (NHANES II) of USA has provided a good opportunity to define more precisely the cut-off points, it is doubtful whether the age-related differences in children represent normal development or the effects of iron deficiency. In order to provide information about these aspects the present experimental model was performed: weanling Wistar rats were fed until 95 days of age (t 95) with an isocaloric diet containing 20 or 30 g/100 g. of protein (casein) (N 20 and N 30, respectively), allowing the highest growth and erythropoiesis rates and covering the requirements of all the nutrients (Table 1). Body weight and food intake were recorded three times/week.(ABSTRACT TRUNCATED AT 250 WORDS)