title: Relationship between thyroid nodules and non-functioning adrenal incidentalomas and their association with insulin resistance.
abstract: OBJECTIVE
  The relationship between insulin resistance and thyroid nodules in patients with non-functional adrenal incidentalomas (AI) is not clearly understood. The aim of this study was to determine the frequency of thyroid nodules in AI patients, as well as to evaluate any possible associations with disorders of insulin resistance.
  
  
  METHODS
  Patients diagnosed with a non-functional AI were approached for inclusion in the study. Insulin resistance was evaluated using homeostasis model assessment (HOMA-IR). All participants were screened for the presence of thyroid nodule by ultrasonography, and fine needle aspiration biopsies were obtained from consenting subjects.
  
  
  RESULTS
  One-hundred-thirteen patients with AI and 152 age-, BMI- and gender-matched healthy controls were enrolled. AI patients had higher waist circumference and waist/hip ratio than the control group. Metabolic syndrome, hypertension and type 2 diabetes mellitus rates were significantly higher in AI patients. HOMA-IR was similar between the groups. At least one thyroid nodule was observed in 42 (27.6%) of the controls compared to 55 (48.7%) of AI patients (p < 0.001). The mean number of thyroid nodules in AI patients was significantly higher than the control subjects (2.4 ± 0.9 versus 1.7 ± 1.0, p = 0.008). Mean nodule volume was similar between AI patients and the controls. A correlation could not be established between adrenal tumor/thyroid nodule volumes and the number of thyroid nodules, HOMA-IR, waist circumference, waist/hip ratio, BMI and thyroid function tests.
  
  
  CONCLUSIONS
  A higher prevalence of thyroid nodule and a higher number of thyroid nodules were determined in patients with AI compared to healthy controls.
authors.affiliation: Department of Endocrinology and Metabolism, Ankara Numune Research and Training Hospital, Ministry of Health , Ankara , Turkey.
authors.forename: Ayse
authors.initials: A
authors.lastname: Arduc
authors.forename: Serhat
authors.initials: S
authors.lastname: Isik
authors.forename: Ufuk
authors.initials: U
authors.lastname: Ozuguz
authors.forename: Yasemin Ates
authors.initials: YA
authors.lastname: Tutuncu
authors.forename: Ferit Kerim
authors.initials: FK
authors.lastname: Kucukler
authors.forename: Hatice Nursun
authors.initials: HN
authors.lastname: Ozcan
authors.forename: Dilek
authors.initials: D
authors.lastname: Berker
authors.forename: Serdar
authors.initials: S
authors.lastname: Guler
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000150:complications*; D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005260:Female; D006706:Homeostasis; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications; D008875:Middle Aged; D008954:Models, Biological; D015995:Prevalence; D016606:Thyroid Nodule / Q000150:complications* / Q000000981:diagnostic imaging; D014463:Ultrasonography; D055105:Waist Circumference; D049629:Waist-Hip Ratio
keywords: Adrenal incidentaloma; insulin resistance; insulin-like growth factor 1; obesity; thyroid nodule