Serum Thyrotropin Elevation and Coronary Artery Calcification in Hemodialysis Patients

Abstract

Introduction: Hypothyroidism is highly prevalent in end-stage kidney disease patients, and emerging data show that lower circulating thyroid hormone levels lead to downregulation of vascular calcification inhibitors and coronary artery calcification (CAC) in this population. To date, no studies have examined the association of serum thyrotropin (TSH), the most sensitive and specific single biochemical metric of thyroid function, with CAC risk in hemodialysis patients. Methods: In secondary analyses of patients from the Anti-Inflammatory and Anti-Oxidative Nutrition in Hypoalbuminemic Dialysis Patients trial, we examined serum TSH levels and CAC risk assessed by cardiac computed tomography scans collected within a 90-day period. We evaluated the relationship between serum TSH with CAC Volume (VS) and Agatston score (AS) (defined as >100 mm³ and >100 Houndsfield Units, respectively) using multivariable logistic regression. Results: Among 104 patients who met eligibility criteria, higher TSH levels in the highest tertile were associated with moderately elevated CAC VS and AS in case-mix-adjusted analyses (ref: lowest tertile): adjusted ORs (95% CIs) 4.26 (1.18, 15.40) and 5.53 (1.44, 21.30), respectively. TSH levels >3.0 mIU/L (ref: ≤3.0 mIU/L) were also associated with moderately elevated CAC VS and AS. In secondary analyses, point estimates of incrementally lower direct free thyroxine levels trended toward elevated CAC VS and AS, although associations did not achieve statistical significance. Conclusions: In hemodialysis patients, higher serum TSH was associated with elevated CAC VS and AS. Further studies are needed to determine if thyroid hormone supplementation can attenuate CAC burden in this population.