Prevalence and functional significance of antipituitary antibodies in patients with autoimmune and non-autoimmune thyroid diseases

J Clin Endocrinol Metab. 2007 Jun;92(6):2176-81. doi: 10.1210/jc.2006-2748. Epub 2007 Mar 6.

Abstract

Background: Circulating antipituitary antibodies (APA) are markers of autoimmune hypophysitis, which may cause deficient pituitary function. The prevalence of APA in autoimmune thyroid disorders (AITD) is uncertain.

Objectives: The aims of this study were 1) to evaluate APA prevalence in a large series of patients with AITD and non-AITD and 2) to investigate the functional significance of APA by assessing pituitary function in APA-positive patients.

Design and setting: We conducted a health survey on consecutive AITD and non-AITD patients at a tertiary referral center (Department of Endocrinology, Pisa).

Patients: Subjects, including 1290 consecutive patients with thyroid disorders (961 AITD and 329 non-AITD) and 135 controls, were enrolled in the study.

Methods: APA (indirect immunofluorescence), free T(4), free T(3), TSH, and organ-specific autoantibodies were assayed in all patients. Functional pituitary evaluation was performed in most APA-positive patients.

Results: APA frequency was higher in AITD (11.4%) than in non-AITD (0.9%; P < 0.0001) patients; all control subjects had negative APA tests. APA were more frequently found in Hashimoto's thyroiditis (13%) than in Graves' disease (7.1%; P = 0.05). Of 110 APA-positive AITD patients, 20 (18.2%) had autoimmune polyglandular syndrome, whereas 90 (81.8%) had apparently isolated AITD. APA positivity increased percentage of autoimmune polyglandular syndrome in our series from 10.4 to 13.5%. Of 110 APA-positive patients, 102 were submitted to dynamic testing for functional pituitary assessment; 36 patients (35.2%) had mild or severe GH deficiency (GHD). No additional anterior pituitary hormone deficiencies were found; one patient had central diabetes insipidus. Pituitary abnormalities at magnetic resonance imaging were found in most APA-positive GHD patients.

Conclusions: APA are frequently present in patients with AITD. Patients should be tested for APA because positive tests are associated with GHD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Autoantibodies / blood*
  • Child
  • Diabetes Insipidus, Neurogenic / epidemiology
  • Diabetes Insipidus, Neurogenic / immunology
  • Female
  • Graves Disease / epidemiology
  • Graves Disease / immunology
  • Hashimoto Disease / epidemiology*
  • Hashimoto Disease / immunology*
  • Health Surveys
  • Humans
  • Hypopituitarism / epidemiology*
  • Hypopituitarism / immunology*
  • Male
  • Middle Aged
  • Pituitary Diseases / epidemiology
  • Pituitary Diseases / immunology
  • Seroepidemiologic Studies

Substances

  • Autoantibodies