Anaemia and its association with iron, vitamin B 12 and folate deficiency in school-age children and adolescents: a cross-sectional study of primary-care laboratory records (2019–2025)

Objective To determine the frequency of anaemia and its association with iron, vitamin B 12 and folate deficiency in school-age children and adolescents. Design Cross-sectional study. Setting Family health centres (primary care) in Antalya, Türkiye, 2019–2025. Participants Children aged 6–18 years with a complete blood count; the first eligible record per child was analysed (n=240 613). Main outcome measures Anaemia, defined by WHO age-specific and sex-specific haemoglobin thresholds; iron (ferritin <15 µg/L or transferrin saturation <16%), vitamin B 12 (<200 pg/mL) and folate (<3 ng/mL) deficiency; associations assessed by χ² test, ORs and multivariable logistic regression. Because total iron-binding capacity was not measured directly, transferrin saturation was derived as serum iron divided by the sum of serum iron and unsaturated iron-binding capacity, expressed as a percentage; iron deficiency was defined as ferritin <15 µg/L or transferrin saturation <16%, whichever was available. Results Anaemia prevalence was 9.5% (95% CI 9.4% to 9.6%), higher in girls (13.6%) than boys (4.2%) and rising with age (6–11 years 4.8%; 15–18 years 12.9%; both p<0.001). Most anaemia was microcytic (76.0%). Iron deficiency was present in 50.4%, vitamin B 12 deficiency in 53.7% and folate deficiency in 0.8%. In multivariable analysis, iron deficiency (adjusted OR 4.15, 95% CI 3.99 to 4.31), female sex and older age were independently associated with anaemia (all p<0.001). Conclusions Anaemia remains common and largely preventable in school-age children and adolescents, with iron deficiency as the principal correlate. Adolescent girls are the priority group for iron-status screening and intervention.