title: Central hypothyroidism in a patient with pituitary autoimmunity: evidence for TSH-independent thyroid hormone synthesis.
abstract: BACKGROUND
  Acquired central hypothyroidism is rare, especially when isolated, and is typically associated with detectable, although biologically inactive, serum TSH.
  
  
  OBJECTIVE
  We describe a 56-yr-old woman with profound central hypothyroidism and partial central hypoadrenalism, in the absence of other endocrine abnormalities. In contrast to most cases of central hypothyroidism, serum TSH remained undetectable for 9 months before the initiation of thyroid hormone and hydrocortisone treatment. A test for pituitary autoantibody was moderately positive. Serum free T(4), serum T(3), and neck radioiodine uptake were low but detectable. The thyroid and pituitary glands appeared morphologically normal on neck ultrasound and head magnetic resonance imaging, respectively.
  
  
  METHODS
  The study was conducted in a tertiary academic medical center.
  
  
  CONCLUSIONS
  This case illustrates the variable clinical presentation of pituitary autoimmunity. The persistence of low but detectable thyroid hormone levels and radioiodine neck uptake in the absence of TSH suggests that significant TSH-independent thyroid hormone synthesis may occur in the normal thyroid.
authors.affiliation: Thyroid Unit and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. gbarbesino@partners.org
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Barbesino
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Sluss
authors.forename: Patrizio
authors.initials: P
authors.lastname: Caturegli
mesh_terms: D020274:Autoimmune Diseases of the Nervous System / Q000097:blood / Q000150:complications* / Q000378:metabolism; D015551:Autoimmunity / Q000502:physiology*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications / Q000209:etiology* / Q000378:metabolism; D008875:Middle Aged; D010900:Pituitary Diseases / Q000097:blood / Q000150:complications* / Q000378:metabolism; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000096:biosynthesis* / Q000097:blood; D013972:Thyrotropin / Q000097:blood / Q000502:physiology
chemical_list: D013963:Thyroid Hormones; D013972:Thyrotropin
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