Hypothyroidism classification

Hypothyroidism Main page
Patient Information
Overview
Classification Primary hypothyroidism Hashimoto's thyroiditis Secondary hypothyroidism Tertiary hypothyroidism
Differentiating different causes of hypothyroidism
Screening
Diagnosis
History and symptoms

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Classification

Hypothyroidism is often classified by the organ of origin:

Type	Origin	Description
Primary hypothyroidism	thyroid gland	The most common forms include Hashimoto's thyroiditis (an autoimmune disease) and radioiodine therapy for hyperthyroidism.
Secondary hypothyroidism	pituitary gland	Occurs if the pituitary gland does not create enough thyroid stimulating hormone (TSH, Thyrotropin) to induce the thyroid gland to create a sufficient quantity of thyroxine. Although not every case of secondary hypothyroidism has a clear-cut cause, it is usually caused when the pituitary is damaged by a tumor, radiation, or surgery so that it is no longer able to instruct the thyroid to make enough hormone
Tertiary hypothyroidism, also called hypothalamic-pituitary-axis hypothyroidism	hypothalamus	Results when the hypothalamus fails to produce sufficient TRH.