What This Trial Looked At
Hashimoto’s thyroiditis is the most common cause of hypothyroidism in much of the world. It is an autoimmune condition: the immune system progressively damages the thyroid gland, and most patients end up on lifelong thyroid hormone replacement (typically levothyroxine) to compensate. There is no established treatment that targets the underlying autoimmune attack itself. In 2013 a Brazilian research team led by Höfling and Chavantes published a randomised, placebo-controlled trial in Lasers in Medical Science testing whether low-level laser therapy — already used in other autoimmune and inflammatory contexts — could meaningfully shift the course of the disease.
The study enrolled 43 patients with hypothyroidism caused by chronic autoimmune thyroiditis. Participants were randomised to receive either ten sessions of low-level infrared laser therapy applied over the thyroid region, or sham (placebo) treatment, twice weekly for five weeks. Outcomes tracked included thyroid function tests (TSH, free T4), thyroid peroxidase antibody levels (TPOAb, the hallmark of Hashimoto’s autoimmune activity), thyroid ultrasound findings, and the dose of levothyroxine replacement therapy required to maintain euthyroid status.
What They Found
The laser-treated group showed measurable improvements across the key biological markers of the disease. Thyroid function improved on biochemical testing. Levels of thyroid peroxidase antibodies — the immunological footprint of Hashimoto’s — decreased significantly compared with the placebo group. Importantly, the laser group also required a lower dose of levothyroxine replacement therapy, with several patients able to reduce their thyroid medication.
A long-term follow-up six years after the initial trial reinforced the durability of these findings: the laser group still showed lower TPOAb levels and lower levothyroxine dose requirements compared with the original placebo group, with no new thyroid nodules observed in the follow-up window.
What This Means in Context
This is an intriguing trial with consistent follow-up data, but it sits in a fairly narrow corner of the photobiomodulation literature. The work has been largely conducted by a single research group, and broader independent replication in other centres is still limited. The findings should be read as a promising signal in an under-studied clinical area rather than as a settled body of evidence.
What gives the trial weight is the design — randomised and placebo-controlled, with objective biochemical endpoints — and the consistency between the original outcomes and the long-term follow-up. For a chronic autoimmune condition that conventional medicine treats only symptomatically through hormone replacement, the possibility that a non-pharmacological intervention may modify disease activity at the immunological level is worth taking seriously.
What It Means for You
If you are managing hypothyroidism from Hashimoto’s thyroiditis, this trial suggests photobiomodulation may have a role to play alongside the standard hormone-replacement approach — particularly in supporting reduced antibody activity and possibly reducing medication requirements over time. The evidence base is still narrow and the protocol used in the trial was clinical (infrared laser sessions, twice weekly). Any change to your thyroid management must be coordinated with the endocrinologist managing your care, including any consideration of lowering your levothyroxine dose.
Citation: Höfling, D.B., Chavantes, M.C., Juliano, A.G., Cerri, G.G., Knobel, M., Yoshimura, E.M., & Chammas, M.C. (2013). Low-level laser in the treatment of patients with hypothyroidism induced by chronic autoimmune thyroiditis: a randomized, placebo-controlled clinical trial. Lasers in Medical Science, 28(3), 743–753. PubMed
