title: The starting dose of levothyroxine in primary hypothyroidism treatment: a prospective, randomized, double-blind trial.
abstract: BACKGROUND
  The treatment of hypothyroidism with levothyroxine is effective and simple; however, recommendations for the starting dose vary considerably. To our knowledge, the levothyroxine starting dose has never been studied prospectively.
  
  
  METHODS
  We conducted a prospective, randomized, double-blind trial that compared a full starting levothyroxine dose of 1.6 mug/kg with a low starting dose of 25 mug (increased every 4 weeks) in patients with newly diagnosed cardiac asymptomatic hypothyroidism. Safety was studied by documenting cardiac symptoms and events, and efficacy was studied by monitoring thyrotropin and free thyroxine levels and by assessing improvement of signs and symptoms and quality of life.
  
  
  RESULTS
  Seventy-five consecutive patients were enrolled, of whom 50 underwent randomization. At baseline, the severity of hypothyroidism and age were comparable in the full-dose (n = 25) vs the low-dose group (n = 25): thyrotropin, 61 vs 48 mIU/L; free thyroxine, 0.56 vs 0.64 ng/dL (7.2 vs 8.2 pmol/L); and age, 47 vs 47 years. No cardiac complaints or events were documented during treatment or at bicycle ergometry at baseline, 12 weeks, or 24 weeks. Euthyroidism was reached in the full-dose vs the low-dose group in 13 vs 1 (4 weeks), 19 vs 3 (8 weeks), 19 vs 9 (12 weeks), 20 vs 14 (16 weeks), 20 vs 18 (20 weeks), and 21 vs 20 (24 weeks) patients (P = .005). However, signs and symptoms of hypothyroidism and quality of life improved at a comparable rate.
  
  
  CONCLUSIONS
  A full starting dose of levothyroxine in cardiac asymptomatic patients with primary hypothyroidism is safe and may be more convenient and cost-effective than a low starting dose regimen.
authors.affiliation: Department of Internal Medicine, Medical Centre Rijnmond-Zuid, Rotterdam, Department of Cardiology, Erasmus Medical Centre, Rotterdam, the Netherlands.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Roos
authors.forename: Suzanne P
authors.initials: SP
authors.lastname: Linn-Rasker
authors.forename: Ron T
authors.initials: RT
authors.lastname: van Domburg
authors.forename: Jan P
authors.initials: JP
authors.lastname: Tijssen
authors.forename: Arie
authors.initials: A
authors.lastname: Berghout
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D006207:Half-Life; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000008:administration & dosage*
chemical_list: D013972:Thyrotropin; D013974:Thyroxine