title: A pilot study of active vitamin D administration and insulin resistance in African American patients undergoing chronic hemodialysis.
abstract: OBJECTIVE
  Insulin resistance (IR) is associated with increased cardiovascular risk in multiple patient populations, including those undergoing chronic hemodialysis (CHD). Active vitamin D deficiency has been proposed to play a role in the extent of IR observed in patients with CHD. We postulated that administration of paracalcitol, an active vitamin D medication, influences IR in patients with CHD.
  
  
  METHODS
  This was a pilot randomized controlled trial. Ten prevalent CHD patients receiving a stable dose of paracalcitol were recruited. Paracalcitol was withheld for 8 weeks in all patients (phase I). Parathyroid hormone levels were managed with the calcium-sensing receptor agonist cinacalcet. At week 8, patients were randomized to continue cinacalcet or to restart paracalcitol for 8 weeks (phase II). The primary outcome was the change in IR measured by the glucose disposal rate (GDR) using hyperinsulinemic euglycemic clamp (HEGC) method. Secondary outcomes included changes in IR between groups in indirect indices of IR, biomarkers of inflammation, and adipokine levels.
  
  
  RESULTS
  The mean age was 49 years (range, 46-57 years) and 40% of patients were women. There was no detectable change in the GDR at the end of phase I (P = .7) when compared with baseline values. There was also no statistically significant difference in GDR between groups at the end of phase II (P = .9). No changes were observed in indirect indices of IR, adipokine levels, or biomarkers of inflammation in either phase.
  
  
  CONCLUSIONS
  The results of this pilot study suggest that withdrawal of paracalcitol over 8 to 16 weeks and replacement for 8 weeks after withdrawal does not influence IR measured by HEGC in patients receiving CHD.
authors.affiliation: Clinical Science Research and Development, Veterans Administration Tennessee Valley Healthcare System, Nashville, Tennessee, USA.
authors.forename: Adriana M
authors.initials: AM
authors.lastname: Hung
authors.forename: Mary B
authors.initials: MB
authors.lastname: Sundell
authors.forename: Natalia E
authors.initials: NE
authors.lastname: Plotnikova
authors.forename: Aihua
authors.initials: A
authors.lastname: Bian
authors.forename: Ayumi
authors.initials: A
authors.lastname: Shintani
authors.forename: Charles D
authors.initials: CD
authors.lastname: Ellis
authors.forename: Edward D
authors.initials: ED
authors.lastname: Siew
authors.forename: T Alp
authors.initials: TA
authors.lastname: Ikizler
mesh_terms: D015502:Absorptiometry, Photon; D054392:Adipokines / Q000097:blood; D001741:Black or African American; D015415:Biomarkers / Q000097:blood; D001823:Body Composition; D002318:Cardiovascular Diseases / Q000453:epidemiology; D002908:Chronic Disease; D000069449:Cinacalcet; D004311:Double-Blind Method; D023381:Endpoint Determination; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism / Q000453:epidemiology; D007249:Inflammation / Q000150:complications; D007333:Insulin Resistance; D007676:Kidney Failure, Chronic / Q000150:complications / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009281:Naphthalenes / Q000494:pharmacology; D010281:Parathyroid Hormone / Q000097:blood; D010865:Pilot Projects; D044169:Receptors, Calcium-Sensing / Q000819:agonists / Q000378:metabolism; D006435:Renal Dialysis; D012307:Risk Factors; D014807:Vitamin D / Q000008:administration & dosage*; D014808:Vitamin D Deficiency / Q000150:complications / Q000188:drug therapy
chemical_list: D054392:Adipokines; D015415:Biomarkers; D009281:Naphthalenes; D010281:Parathyroid Hormone; D044169:Receptors, Calcium-Sensing; D014807:Vitamin D; D000069449:Cinacalcet