Levothyroxine Treatment and Cardiovascular Outcomes in Older People With Subclinical Hypothyroidism: Pooled Individual Results of Two Randomised Controlled Trials.

Frontiers in endocrinology · January 2021 · Laurien E Zijlstra, J Wouter Jukema, Rudi G J Westendorp, Robert S Du Puy, Rosalinde K E Poortvliet, et al.

What this study found

Treatment with levothyroxine did not significantly change the risk of cardiovascular outcomes in older adults with subclinical hypothyroidism, irrespective of a history of cardiovascular disease and age. CLINICAL TRIAL REGISTRATION: [ClinicalTrials.gov], identifier [NCT01660126] (TRUST); Netherlands Trial Register: NT…

Open on PubMed DOI

Landmark studyrctNCT01660126

Why this trial matters

Subclinical hypothyroidism CV pooled analysis

How RAGMD uses this study

Clinical questions this paper informs

Synthesis lives on the evidence question — this page shows where the study sits in that analysis.

Primary study

What TSH target is appropriate for treated hypothyroidism?

Most guidelines suggest maintaining TSH within the reference range on levothyroxine, often near the lower half for many patients. Pregnancy and specific comorbidities require tighter targets.

Open evidence analysis

Primary study

Does treated hypothyroidism fully explain difficulty losing weight?

Hypothyroidism can contribute to weight gain, but levothyroxine normalization typically yields modest weight loss rather than resolving obesity. Persistent weight difficulty usually involves additional metabolic and behavioral factors.

Open evidence analysis

Supporting literature

Does combination T3/T4 therapy improve symptoms versus levothyroxine alone?

Randomized trials and meta-analyses show inconsistent symptom benefit from adding liothyronine to levothyroxine compared with levothyroxine monotherapy. Guidelines generally recommend levothyroxine as first-line therapy.

Open evidence analysis

Supporting literature

Should subclinical hypothyroidism be treated with levothyroxine?

The TRUST trial found no meaningful symptom or quality-of-life benefit from levothyroxine in older adults with subclinical hypothyroidism. Treatment may still be considered with very high TSH, pregnancy plans, or specific clinical contexts.

Open evidence analysis

Supporting literature

Is desiccated thyroid extract superior to levothyroxine for hypothyroidism?

Levothyroxine is standard first-line therapy with the strongest outcome evidence. Desiccated thyroid extract lacks modern RCT data demonstrating superiority and has variable hormone content between batches.

Open evidence analysis

Supporting literature

What factors interfere with levothyroxine absorption?

Levothyroxine absorption is reduced by concurrent iron, calcium, PPIs, and some foods including coffee and fiber. Consistent fasting dosing separated from interfering substances improves TSH stability.

Open evidence analysis

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