Hypothyroidism associated with anti-human chorionic gonadotropin antibodies secondarily produced by gonadotropin therapy in a case of idiopathic hypothalamic hypogonadism

T. Ogura, Yukari Mimura, Fumio Otsuka, M. Kishida, K. Yokota, J. Suzuki, A. Nagai, S. Hirakawa, Hirofumi Makino, K. Tobe

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Abstract

We report a 22-yr-old male patient with idiopathic hypothalamic hypogonadism who showed secondary resistance to gonadotropin (Gn) therapy over 3 yr after successful treatment with hCG combined with human menopausal Gn. The patient simultaneously developed subclinical hypothyroidism. Endocrine examination revealed low levels of testosterone (0.3 ng/ml), free T4 (0.91 ng/dl), and increased levels of TSH (31.1 μU/ml) in the serum. Serum autoantibodies to thyroid gland were all negative. Interestingly, thyroid function was improved after discontinuation of Gn therapy. In vitro assays by immunoprecipitation using 125I-hCG or 125I-TSH elucidated the presence of anti-hCG antibody in the serum 13 months after commencement of Gn therapy but anti-TSH antibody was not detected in the serum. Furthermore, the anti-hCG antibody specifically bound to hCG but not to other glycoproteins including TSH and FSH based on a competitive displacement assay. Bioassays using porcine thyroid cells revealed that the serum γ-globulin fraction enables the suppression of cyclic AMP (cAMP) synthesis stimulated by TSH. Our findings suggest that anti-hCG and/or anti-idiotypic hCG antibodies induced by hCG therapy impaired TSH-dependent cAMP production through interfering with binding of TSH to its receptor, and this resulted in subclinical hypothyroidism in this patient.

Original languageEnglish
Pages (from-to)1128-1135
Number of pages8
JournalJournal of Endocrinological Investigation
Volume26
Issue number11
Publication statusPublished - Nov 2003

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Keywords

  • Anti-hCG antibody
  • Gonadotropin
  • Hypothyroidism
  • Idiopathic hypothalamic hypogonadism
  • Immunoprecipitation

ASJC Scopus subject areas

  • Endocrinology

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