Objective: Serum ferritin levels are assumed to be an atherosclerotic risk factor. Ferritin production is increased in individuals with activated liver production, which has been shown in hyperthyroid conditions. An association between subclinical hyperthyroidism and serum ferritin levels would add an explanation to the relation between low serum thyrotropin levels and mortality. The aim of the present analysis was to investigate an association between thyroid function and serum ferritin levels. We hypothesized low serum thyrotropin to be related to high serum ferritin levels.
Design: The Study of Health in Pomerania (SHIP) is a population-based study comprising male and female adults aged 20 to 79 years. Data of 4111 subjects (2071 females) were available for the present analysis. Serum ferritin levels were determined by an immunoturbidimetric assay. Multivariable analyses were performed to investigate an independent relation between thyroid function and serum ferritin levels.
Main outcome: Age-adjusted and gender-stratified analyses revealed no association between thyroid function and serum ferritin levels, neither in females nor in males. This finding remained stable after adjustment for potential confounders and in sensitivity analyses.
Conclusion: There was no association between thyroid function and serum ferritin levels. We conclude that serum ferritin levels do not account for the relation between subclinical hyperthyroidism and vascular mortality.