A 41-year-old woman presented to an endocrinology clinic with nail changes occurring for several months and hair loss that had progressively worsened over two years. Physical examination Dry skin Presentation of thickened and brittle nails with horizontal ridges (Fig. A) Marked hair loss and coarse hair (Fig. B) A diffusely enlarged thyroid gland Laboratory findings Thyrotropin: 30.5 μIU per milliliter Serum free thyroxine: 0.4 ng per deciliter Antithyroglobulin antibody: 793 IU per milliliter Antithyroid peroxidase antibody: 2439 IU per milliliter. Radiological findings Ultrasonography revealed diffuse goiter with heterogeneous internal echogenicity. Five years after the initiation of levothyroxine therapy, the nail changes and hair loss had resolved (Fig.
C and Fig. D) . What is your diagnosis? The correct answer will be posted soon!
