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URL of this page: //medlineplus.gov/ency/imagepages/17126.htm
Primary and secondary hypothyroidism
Overview
Hypothyroidism is a decreased activity of the thyroid gland which may affect all body functions. The rate of metabolism slows causing mental and physical sluggishness. The most severe form of hypothyroidism is myxedema, a medical emergency. Hypothyroidism can be caused by a problem with the thyroid itself (primary), or by the malfunction of the pituitary gland or hypothalamus (secondary).
Review Date 8/19/2026
Updated by: Nowreen Haq, MD, MPH, Specialist in Endocrinology, Obesity Medicine and Internal Medicine. Medical director, ICON Plc and Maryland Endocrinology, Maryland. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
