title: Myotonic dystrophy associated with variable circadian rhythms of serum cortisol and isolated thyrotropin deficiency.
abstract: We describe a case of myotonic dystrophy presenting with a disturbed circadian rhythm of the serum cortisol and an isolated thyrotropin deficiency. The diagnosis of myotonic dystrophy was based on clinical characteristics, positive electromyographic findings, and increased number of CTG repeats in the dystrophia myotonica protein kinase (DMPK) gene. The patient presented with a variable circadian rhythm of the serum cortisol, increased excretion of urinary free cortisol, and a high adrenocorticotropin hormone responses to corticotropin-releasing hormone. The basal serum thyrotropin concentration was low and did not increase after thyrotropin-releasing hormone stimulation. The protein encoded by the DMPK gene may act as a second messenger in signal transduction, like a protein kinase. The present patient had a diverse pattern of disturbances in the hypothalamus-pituitary-endocrine organ axis, probably mediated by differences in the action or expression of the gene products in each endocrine cell.
authors.affiliation: Department of Medicine, Koshigaya Hospital, Dokkyo University School of Medicine, Saitama, Japan.
authors.forename: Ki-ichi
authors.initials: K
authors.lastname: Okumura
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Aso
authors.forename: Kazumi
authors.initials: K
authors.lastname: Tayama
authors.forename: Noboru
authors.initials: N
authors.lastname: Yoshida
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Takiguchi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takemura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Inukai
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D002940:Circadian Rhythm; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000652:urine; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000209:etiology*; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D013972:Thyrotropin / Q000172:deficiency*; D013997:Time Factors
chemical_list: C585517:DMPK protein, human; D000324:Adrenocorticotropic Hormone; D013972:Thyrotropin; D003346:Corticotropin-Releasing Hormone; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases; D006854:Hydrocortisone