title: Parathyroid hormone and insulin resistance in distinct phenotypes of severe obesity: a cross-sectional analysis in middle-aged men and premenopausal women.
abstract: BACKGROUND
  High levels of PTH are reported in obese individuals and related to increased cardiometabolic risk.
  
  
  OBJECTIVE
  Our objective was to evaluate whether the relationship between PTH, insulin resistance, and related metabolic parameters differ between metabolically healthy obese (MHO) and insulin-resistant obese (IRO) subjects.
  
  
  METHODS
  We conducted a cross-sectional study among patients evaluated for bariatric surgery in our University Hospital.
  
  
  METHODS
  Patients initially included were 174 severely obese subjects (114 women, aged 40 ± 5 yr, body mass index of 45 ± 6 kg/m(2)) without diabetes, chronic kidney disease, or hyperparathyroidism. MHO (n = 43) and IRO (n = 86) subjects were identified according to quartiles of insulin resistance.
  
  
  METHODS
  Fasting and postload glucose, insulin, total and high-density lipoprotein cholesterol, triglycerides, creatinine, calcium, phosphorus, PTH, 25-hydroxyvitamin D (25OHD), fibrinogen, and high-sensitivity C-reactive protein were assessed. Insulin sensitivity index was derived from a 75-g oral glucose tolerance test. Fat distribution and bone mineral density were assessed with dual-energy x-ray absorptiometry.
  
  
  RESULTS
  Although 25OHD levels were higher in MHO than in IRO subjects [72.23 (59.41-80.36) vs. 52.36 (41.98-62.57) nmol/liter, P = 0.002], PTH levels were comparable between groups (74.4 ± 13.2 vs. 72.1 ± 15.1 ng/liter, P = 0.34). No differences in serum calcium, phosphorus, bone mineral density, and renal function were detected. An independent inverse association between 25OHD and insulin resistance was seen in both groups. In contrast to IRO subjects, after adjusting for covariates, PTH levels were unrelated to insulin sensitivity index, fasting and postload glucose, insulin, and high-sensitivity C-reactive protein in MHO subjects.
  
  
  CONCLUSIONS
  MHO and IRO subjects show comparably high levels of circulating PTH, which are not associated with insulin resistance and related metabolic parameters in MHO subjects. Most of the associations observed in IRO subjects appear to be mediated by greater truncal fat mass.
authors.affiliation: Department of Systems Medicine, University of Rome Tor Vergata, I-00133 Rome, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Bellia
authors.forename: Giorgia
authors.initials: G
authors.lastname: Marinoni
authors.forename: Monica
authors.initials: M
authors.lastname: D'Adamo
authors.forename: Valeria
authors.initials: V
authors.lastname: Guglielmi
authors.forename: Mauro
authors.initials: M
authors.lastname: Lombardo
authors.forename: Giulia
authors.initials: G
authors.lastname: Donadel
authors.forename: Paolo
authors.initials: P
authors.lastname: Gentileschi
authors.forename: Davide
authors.initials: D
authors.lastname: Lauro
authors.forename: Massimo
authors.initials: M
authors.lastname: Federici
authors.forename: Renato
authors.initials: R
authors.lastname: Lauro
authors.forename: Paolo
authors.initials: P
authors.lastname: Sbraccia
mesh_terms: D000328:Adult; D000367:Age Factors; D001823:Body Composition; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood* / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood*; D010641:Phenotype; D017697:Premenopause / Q000097:blood / Q000378:metabolism; D012720:Severity of Illness Index
chemical_list: D007328:Insulin; D010281:Parathyroid Hormone