• Thyroid Dysfunction and 10-Year Incidence of AMD

    By Marianne Doran and selected by Deepak P. Edward, MD

    Journal Highlights

    Investigative Ophthalmology & Visual Science

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    Epidemiological evidence on the possible relationship between thyroid dysfunction and age-related macular degeneration (AMD) is unclear. Thus, Gopinath et al. analyzed data from the Blue Mountains Eye Study (BMES) to assess the prospective associations between serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) measurements, as well as thyroid dysfunction (hyperthyroidism and hypothyroidism) and the incidence of AMD. They found an independent association between overt hyperthy­roidism and the incidence of AMD; thyroxine usage was also associated with AMD.

    Categories of thyroid dysfunction were defined according to a serum TSH screen followed by serum FT4 assess­ment, and were available for 906 par­ticipants aged 55 years or older (the age group at risk for AMD). These param­eters were not recorded at the original BMES baseline. Thus, the time frame for this study spanned BMES-2, 1997-1999, to BMES-3, 2007-2009. AMD was assessed from retinal photographs. The researchers also studied covariates, including history of smoking, frequen­cy of consuming fish, and the presence of an AMD susceptibility gene.

    After adjusting for covariates, the researchers found that participants with overt hyperthyroidism (low TSH and high FT4 levels) had a 3-fold increased risk of developing incident AMD compared with participants with normal thyroid function (odds ratio [OR], 3.51). Thyroxine usage was also positively associated with the incidence of AMD; those who reported current use of thyroxine had increased risk of incident AMD compared with nonusers (OR, 1.68). Similarly, participants who had ever taken thyroxine medication had a higher risk of AMD (OR, 1.91) than those who had never taken the drug. However, baseline serum TSH or FT4 levels per se did not show an association with 5- or 10-year incidence of AMD.

    The researchers concluded that im­proved knowledge of risk factors could help to develop comprehensive screen­ing strategies for AMD. They suggested that consideration of thyroid disease might contribute to a better profiling of AMD in clinical practice.

    The original article can be found here.