RESUMEN
Anemia (An) is a public health problem in South America, with iron deficiency (ID) as the main cause. In high-altitude cities, hypobaric hypoxia causes an increase in hemoglobin (Hb) levels in residents. For the diagnosis of An, Hb is measured, which is modified after erythrocyte indices (EI) measurements. There is evidence that there is an overestimation of the prevalence of An at high altitudes. OBJECTIVE: To correlate serum ferritin (SF) with Hb and EI, and to determine the Hb cut-off point for predicting ID in 6-month-old infants at 3400 m of altitude. SUBJECTS AND METHOD: 128 infants aged 6 months at 3400 m altitude were evaluated. The SF was considered an independent variable. IE and Hb were the dependent variables. The An in the infant was defined with an Hb < 13.4 g/dl. The DH was defined by FS <12 ug/dL. Data were processed in SPSS® version 25. Spearman correlation was used for bivariate analysis. The ROC curve was constructed to determine the Hb cut-off point for ID. RESULTS: The highest correlation of SF was observed with mean corpuscular hemoglobin (MCH), rho = 0.449 (p < 0.001), and mean corpuscular volume (MCV) rho= 0.423 (p < 0.001). The Hb cut-off point according to SF, defining ID was 12.15 g/dL (ROC curve: 0.704; 95% CI: 0.597-0.811; p < 0.001). CONCLUSION: MCV and MCH showed a better correlation with SF. The cubic and logarithmic models were the ones that best represented these relationships, respectively. Hb < 12.15 g/dL allows diagnosing ID in 6-month-old infants at 3400 m altitude.