Evaluation of a model of latent pathologic factors in relation to serum ferritin elevation

Objectives: Serum ferritin increases in various disorders and clinical conditions. However, causal associations between the serum ferritin level and clinical factors that influence serum ferritin level are not well characterized. We report a model that quantitatively analyzes the causal relations between the serum ferritin level and clinical factors. Design and methods: We analyzed the ferritin level and other laboratory data in the sera of 274 patients. Structural equation modeling was used to verify causal relations and the adequacy of latent factors. Results: Three factors representing clinical status were identified: cell damage, hepatic function, and inflammation. Serum iron (SI) had the strongest effect on serum ferritin elevation. The effect of the cell damage factor on serum ferritin indicated cell destruction, and that of the hepatic function factor represented decreased serum ferritin clearance. The cell damage factor also indirectly increased the ferritin level via SI or the hepatic function factor. The total effect of the inflammatory status factor on ferritin level was very weak. Conclusions: These causal relations may explain the mechanism of serum ferritin level elevation in various clinical conditions.