EFFECT OF A MILD INFECTION ON SERUM FERRITIN CONCENTRATION - CLINICALAND EPIDEMIOLOGIC IMPLICATIONS

Objectives: To study the distribution of serum ferritin concentration in adolescent boys and girls with and without a preceding mild infecti on. Design: The prevalence of iron deficiency was studied in two repre sentative samples. The first sample from 1990 comprised 207 boys and 2 20 girls. The second sample from 1994 included 620 boys and 624 girls. In total 1675 adolescents, 15-16 y old, 827 boys and 844 girls were s tudied. Results: A significant shift of serum ferritin concentration t owards higher values was observed in those who reported an upper respi ratory infection with fever during the preceding month (P < 0.001). Si gnificant differences were found between serum ferritin values in heal thy, not infected adolescents and serum ferritin values in those with ongoing infection, both in boys and girls in the two materials (P < 0. 01), and in those with a mild infection during the preceding three wee ks. Conclusions: The prevalence of recent infection should be included as information when trying to assess the prevalence of iron deficienc y on the basis of serum ferritin measurements and when examining relat ionships between iron status and composition of the diet. The findings imply that differences in prevalence of iron deficiency between diffe rent studies might partly be explained by differences in prevalence of simple respiratory infections. The diagnostic sensitivity of the seru m ferritin assay for iron deficiency, using conventional reference lim its, decreases for subjects with recent such infections; similarly, th ere will be a decrease in the diagnostic specificity for haemochromato sis. Sponsorship: Swedish Medical Research Council (project B9519X-047 21-20B) and Swedish Dairy Association, Stockholm.