Morning vs evening dosing of levothyroxine

January 01, 0001

Morning vs evening dosing of levothyroxine

Usual instructions are to take levothyroxine in the morning on an empty stomach. These Dutch investigators conducted a randomized controlled, crossover trial to ascertain if levothyroxine intake at bedtime instead of in the morning improves thyroid hormone levels. They enrolled 105 consecutive patients with primary hypothyroidism at Maasstad Hospital Rotterdam in the Netherlands. Patients were instructed during 6 months to take 1 capsule in the morning and 1 capsule at bedtime (one containing levothyroxine and the other a placebo), with a switch after 3 months.

They found: "Ninety patients completed the trial and were available for analysis. Compared with morning intake, direct treatment effects when levothyroxine was taken at bedtime were a decrease in thyrotropin level of 1.25 mIU/L, an increase in free thyroxine level of 0.07 ng/dL, and an increase in total triiodothyronine level of 6.5 ng/dL (to convert thyrotropin level to micrograms per liter, multiply by 1.0; free thyroxine level to picomoles per liter, multiply by 12.871; and total triiodothyronine level to nanomoles per liter, multiply by 0.0154). Secondary outcomes, including quality-of-life questionnaires (36-Item Short Form Health Survey, Hospital Anxiety and Depression Scale, 20-Item Multidimensional Fatigue Inventory, and a symptoms questionnaire), showed no significant changes between morning vs bedtime intake of levothyroxine."

The authors concluded: "Levothyroxine taken at bedtime significantly improved thyroid hormone levels. Quality-of-life variables and plasma lipid levels showed no significant changes with bedtime vs morning intake. Clinicians should consider prescribing levothyroxine intake at bedtime."

The outcomes patients care about were equivalent with either morning or bedtime dosing.

For the full abstract, click here.

Arch Intern Med 170(22):1996-2003, 13/27 December 2010
© 2010 to the American Medical Association
Effects of Evening vs Morning Levothyroxine Intake-A Randomized Double-blind Crossover Trial. Nienke Bolk, Theo J. Visser, Judy Nijman, Ineke J. Jongste, Jan G. P. Tijssen, Arie Berghout. Correspondence to Dr. Bolk: [email protected]

Category: T. Endocrine/Metabolic/Nutritional. Keywords: levothyroxine, hypothyroidism, bedtime, randomized controlled trial, journal watch.
Synopsis edited by Dr Linda French, Toledo, Ohio. Posted on Global Family Doctor 4 January 2011

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