The Starting Dose of Levothyroxine in Primary Hypothyroidism Treatment
A Prospective, Randomized, Double-blind Trial
Annemieke Roos; Suzanne P. Linn-Rasker; Ron T. van Domburg; Jan P. Tijssen; Arie Berghout
Arch Intern Med. 2005;165:1714-1720
Aanbeveling NIV-Richtlijn Schildklierfunctiestoornissen, pagina 130
Bij de behandeling van primaire hypothyreoïdie bij gezonde patiënten kan met een volledige substitutiedosis worden gestart. Bij patiënten van 60 jaar en ouder of bij patiënten met cardiovasculaire co-morbiditeit wordt een lagere startdosering geadviseerd.
Beleid behandeling hypothyreoïdie met levothyroxine
NHG-Standaard Schildklieraandoeningen (tweede herziening)
BackgroundThe 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.
MethodsWe conducted a prospective, randomized, double-blind trial that compared a full starting levothyroxine dose of 1.6 μg/kg with a low starting dose of 25 μg (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.
- 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.