AHDS, Allan-Herndon-Dudley syndrome; BBB, blood brain barrier; BSA, body surface area; CON, healthy control group in our study; CRP, C reactive protein; CSF, cerebrospinal fluid; DIO2, type II iodothyronine deiodinase-enzyme; GHLS, General Health Likert Scale; HYP, hypothyroid subjects in our study; Hb, hemoglobulin; M, mean value; MADRS; MADRS, Montgomery Asberg Depression Rating Scale; MCT8, monocarboxylate transporter 8; Md, median value; Mild hypothyroidism; NS, non-significant; OATP1C1, organic anion transporter polypeptide 1C1; PH, primary hypothyroidism in general; Q1, first quartile; Q3, third quartile; QoL, quality of life; Quality of life; Subclinical hypothyroidism; T3, triiodothyronine; T4, thyroxine; TPO, thyroid peroxidase antibody; TSH, thyroid stimulating hormone; Thyroxine; Triiodothyronine; f-T3 and f-T4, free unbound thyroid hormone; s-, serum