Lower hemoglobin with lower ferritin: It is not just a question of anemia

Aim. To study the association between blood hemoglobin concentration (b-hemoglobin) and serum ferritin concentration (s-ferritin) in an ambulant patient population without inflammation and with normal kidney function. Methods. In ambulant, adult patients with normal values of s-CRP and s-creatinine, median b-hemoglobin and the fraction with anemia was compared in groups with lower s-ferritin from a level of 100 mu g/L. The 10, 50 and 90 percentiles of b-hemoglobin were modelled as functions of s-ferritin using quantile regression. Results. Among 3206 women the entire b-hemoglobin distribution was shifted downwards in patients with s-ferritin less than 20 mu g/L. Accordingly, the median b-hemoglobin was statistically significantly lower and the fraction with anemia was higher. In 1246 men the findings were similar, except that the turning point toward lower b-hemoglobin was at a s-ferritin level of 30 mu g/L. Conclusions. Low s-ferritin is associated with decreased b-hemoglobin in many more subjects than those labelled anemic.