title: Uric Acid-Induced Inflammation Is Mediated by the Parathyroid Hormone:25-Hydroxyvitamin D Ratio in Obese Adolescents.
abstract: BACKGROUND
  Elevated serum uric acid (SUA) level is strongly associated with prevalence of metabolic syndrome (MS), elevated parathyroid hormone (PTH) levels, and 25-hydroxyvitamin D [25(OH)D] insufficiency in adults. We examined the relationship among SUA, [25(OH)D], PTH, and inflammation in obese adolescents, in obese adolescents with and without MS.
  
  
  METHODS
  Body mass index, body composition, 25(OH)D, PTH, fasting lipids, glucose, high-sensitivity C-reactive protein (hs-CRP), SUA, hemoglobin A1c (HbA1c), insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR) were evaluated in 152 obese adolescents.
  
  
  RESULTS
  Hyperuricemia [SUA ≥ 6.0 mg/dL (357 μM)] was present in 54.6% of entire cohort without significant ethnic/racial differences. While SUA was negatively correlated with high-density lipoprotein cholesterol (HDL-C) and 25(OH)D (P < 0.01), it was positively correlated with fat mass (FM), PTH, PTH:25(OH)D, and hs-CRP (P < 0.01). Vitamin D deficiency [25(OH)D <50 nM] was present in 47.4% of subjects, and PTH and 25(OH)D were inversely correlated (P < 0.0001). FM was negatively correlated with 25(OH)D (r = -0.29; P < 0.001), but was positively correlated with PTH (P < 0.0001). MS was identified in 53.3% of cohort with higher FM, SUA, hs-CRP, HOMA-IR, PTH, and PTH:25(OH)D ratio than the non-MS subgroup (P < 0.001) with similar 25(OH)D status. Multiple regression analysis showed that the PTH:25(OH)D ratio mediated the relationship between SUA and hs-CRP (β = 0.19, P < 0.05 to β = 0.15, P = 0.19).
  
  
  CONCLUSIONS
  Hyperuricemia is strongly associated with PTH and hs-CRP levels independent of vitamin D status. The relationship between SUA and low-grade inflammation is mediated by the PTH:25(OH)D ratio in obese adolescents.
authors.affiliation: 1 Division of Pediatric Endocrinology, Department of Pediatrics, University of Tennessee Health Science Center , Le Bonheur Research Center, Memphis, Tennessee.
authors.forename: Ramin
authors.initials: R
authors.lastname: Alemzadeh
authors.affiliation: 2 Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center , Cincinnati, Ohio.
authors.forename: Jessica
authors.initials: J
authors.lastname: Kichler
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000209:etiology; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000150:complications; D010281:Parathyroid Hormone / Q000097:blood*; D063766:Pediatric Obesity / Q000097:blood* / Q000150:complications; D012189:Retrospective Studies; D014527:Uric Acid / Q000009:adverse effects* / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; D014527:Uric Acid; C104450:25-hydroxyvitamin D