title: Do subtypes of graves' orbitopathy exist?
abstract: OBJECTIVE
  To describe the prevalence of fat and muscle volume (MV) increase in Graves' orbitopathy (GO) patients, calculated from computed tomography scans, and the associated ophthalmic and endocrine characteristics.
  
  
  METHODS
  Consecutive, observational case series.
  
  
  METHODS
  Ninety-five consecutive Caucasian GO patients attending the thyroid eye clinic.
  
  
  METHODS
  Volumetry using age-specific reference values in untreated GO patients who had been rendered euthyroid.
  
  
  METHODS
  Subgroups in GO and main characteristics.
  
  
  RESULTS
  Four subgroups could be distinguished: Group 1, no fat volume (FV) or MV increase (n = 24); group 2, only FV increase (n = 5); group 3, only MV increase (n = 58); and group 4, both FV and MV increase (n = 8). Patients with an increase of MV were older and had higher thyroid-stimulating hormone-binding inhibitory immunoglobulin TBII, more proptosis, and more impaired ductions than those without MV increase. Patients with an increase of FV differed from those without FV increase only in having more proptosis. The clinical activity score did not differ between the 4 groups.
  
  
  CONCLUSIONS
  Of these GO patients, 25% have orbital fat and MVs within an age-specific reference range. An increase of the FV is seen in only 14% of GO patients and characterized by proptosis. Muscle enlargement occurs in 70% of patients and is associated with older age, higher TBII values, more proptosis, and impaired motility.
authors.affiliation: Orbital Centre, Department of Ophthalmology, Academic Medical Centre, University of Amsterdam, The Netherlands. n.i.regensburg@amc.nl
authors.forename: Noortje I
authors.initials: NI
authors.lastname: Regensburg
authors.forename: Wilmar M
authors.initials: WM
authors.lastname: Wiersinga
authors.forename: Tos T J M
authors.initials: TT
authors.lastname: Berendschot
authors.forename: Peter
authors.initials: P
authors.lastname: Potgieser
authors.forename: Maarten P
authors.initials: MP
authors.lastname: Mourits
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000473:pathology*; D000328:Adult; D005260:Female; D049970:Graves Ophthalmopathy / Q000145:classification* / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000000981:diagnostic imaging / Q000473:pathology*; D009916:Orbital Diseases / Q000145:classification* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed