Thyroxine (T4) and triiodothyronine (T3) are produced from the thyroid gland. Thyroid hormones are important in regulating various body functions and their deficiencies are associated with different symptoms including decrease in energy metabolism, decreased appetite, cold intolerance, and lower basal body temperature (due to low basal metabolic rate). Iodine deficiency is recognized as the most common cause of<unk>  world-wide. In developed countries and areas with sufficient iodine, the most common cause of<unk>  is chronic autoimmune thyroiditis (Hashimoto’s thyroiditis). Hashimoto’s thyroiditis has a higher prevalence in women than in men. Signs and symptoms of<unk>  are mostly related to the magnitude of the thyroid hormone deficiency and the acuteness of the development of hormone deficiency. However, the typical clinical manifestations of<unk>  may vary depending on the cause of<unk> . Clinical scenario, if associated with secondary and tertiary<unk> , may present other coexisting endocrine deficiencies such as hypogonadism and adrenal insufficiency that may mask the manifestations of<unk> . Although  the diagnosis of<unk>  is mainly a laboratory diagnosis, the coexisting conditions and wide variation in clinical presentation may make the diagnosis difficult. On the other hand, subclinical<unk>  is mostly asymptomatic, but may transform to clinical<unk> . Recent evidence has shown that subclinical<unk>  may lead to various complications, such as hyperlipidemia, increased risk of cardiovascular disease (even heart failure), somatic and neuromuscular symptoms, and infertility.
Hypothyroidism
Hyerthyroidism
Nodular thyroid disease
Acromegaly
Hypopituitarism
Thyroid adenoma
Toxic multinodular goiter
Hyperprolactinemia