Lasers in Surgery and Medicine 42:589–596 (2010) Low-Level Laser Therapy in Chronic Autoimmune Thyroiditis: A Pilot Study Danilo B. Ho ¨ fling, MD, MS, 1,2 * Maria Cristina Chavantes, MD, PhD, 2 Adriana G. Juliano, MD, 1 Giovanni G. Cerri, MD, 1 Rossana Roma ˜ o, MD, 3 Elisabeth Mateus Yoshimura, PhD, 4 and Maria Cristina Chammas, MD, PhD 1 1 Radiology Institute (InRad), Hospital das Clı´nicas, Faculdade de Medicina da Universidade de Sa˜o Paulo, Avenida Dr. Ene´as de Carvalho Aguiar, 255, 38 andar, CEP 05403-001Sa˜o Paulo, Brazil 2 Laser Medical Center of the Heart Institute (InCor), Hospital das Clı´nicas, Faculdade de Medicina da Universidade de Sa˜o Paulo, Avenida Dr. Ene´as de Carvalho Aguiar, 44, 28 andar, CEP 05403-900Sa˜o Paulo, Brazil 3 Endocrinology and Metabolism Department, Thyroid Unit, Hospital das Clı´nicas, Faculdade de Medicina da Universidade de Sa˜oPaulo, Avenida Dr. Ene´as de Carvalho Aguiar, 255, CEP 05403-900Sa˜o Paulo, Brazil 4 Physic Institute, Nuclear Physic Department, Universidade de Sa˜o Paulo, Rua do Mata˜o, Travessa R, 187, Cidade Universita´ria, CEP 05508-900 Sa˜oPaulo, Brazil Background and Objectives: Chronic autoimmune thyroiditis (CAT) remains the most common cause of acquired hypothyroidism. There is currently no therapy that is capable of regenerating CAT-damaged thyroid tissue. The objective of this study was to gauge the value of applying low-level laser therapy (LLLT) in CAT patients based on both ultrasound studies (USs) and evaluations of thyroid function and thyroid autoanti- bodies. Study Design/Materials and Methods: Fifteen patients who had hypothyroidism caused by CAT and were under- going levothyroxine (LT4) treatment were selected to participate in the study. Patients received 10 applications of LLLT (830 nm, output power 50 mW) in continuous mode, twice a week, using either the punctual technique (8 patients) or the sweep technique (7 patients), with fluence in the range of 38–108 J/cm 2 . USs were performed prior to and 30 days after LLLT. USs included a quantitative analysis of echogenicity through a gray-scale computerized histogram index (EI). Following the second ultrasound (30 days after LLLT), LT4 was discontinued in all patients and, if required, reintroduced. Triiodothyro- nine, thyroxine (T4), free T4, thyrotropin, thyroid peroxi- dase (TPOAb) and thyroglobulin (TgAb) antibodies levels were assessed before LLLT and then 1, 2, 3, 6, and 9 months after LT4 withdrawal. Results: We noted all patients’ reduced LT4 dosage needs, including 7 (47%) who did not require any LT4 through the 9-month follow-up. The LT4 dosage used pre- LLLT (96  22 mg/day) decreased in the 9th month of follow-up (38  23 mg/day; P<0.0001). TPOAb levels also decreased (pre-LLLT ¼ 982  530 U/ml, post-LLLT ¼ 579 454 U/ml; P ¼ 0.016). TgAb levels were not reduced, though we did observe a post-LLLT increase in the EI (pre-LLLT ¼ 0.99  0.09, post-LLLT ¼ 1.21  0.19; P ¼ 0.001). Conclusion: The preliminary results indicate that LLLT promotes the improvement of thyroid function, as patients experienced a decreased need for LT4, a reduction in TPOAb levels, and an increase in parenchymal echogenicity. Lasers Surg. Med. 42:589 – 596, 2010. ß 2010 Wiley-Liss, Inc. Key words: autoimmunity; autoantibodies; Hashimoto’s thyroiditis; hypothyroidism; laser therapy (LLLT); thy- roid; treatment; ultrasonography INTRODUCTION Chronic autoimmune thyroiditis (CAT) is the most common cause of hypothyroidism in iodine-replete geo- graphic areas [1]. An autoimmune dysfunction causes humoral and cellular responses that lead progressively to thyroiditis [2]. There is no effective therapy available that can change the natural history of CAT, which presents with a high incidence of hypothyroidism [1] and requires treatment with levothyroxine (LT4). Few reports exist of patients going into remission and thus no longer needing LT4 therapy [1]. An ideal therapy would be efficient in reestablishing immunological tolerance and regenerating Disclosure of proprietary interests: I certify that I have no affiliation with or financial involvement in any organization or entity with a direct financial interest in the subject matter or materials discussed in the manuscript (e.g., employment, con- sultancies, stock ownership, honoraria) except as discussed in an attachment. Abstract presented at the 29th ASLMS Annual Conference: April 3–5, 2009; Photobiomodulation Session n. 194; National Harbor, Maryland, USA. Contract grant sponsor: Fundac ¸a ˜o de Amparo a ` Pesquisa do Estado de Sa ˜ o Paulo (FAPESP); Contract grant sponsor: Conselho Nacional de Desenvolvimento Cientı ´fico e Tecnolo ´gico (CNPq); Contract grant sponsor: Coordenac ¸a ˜o de Aperfeic ¸oamento de Pessoal de Nı ´vel Superior (CAPES). *Correspondence to: Danilo B. Ho ¨ fling, MD, MS, Rua Tabapua ˜, 111, 98 andar, CEP 04533-010, Itaim-Bibi, Sa ˜ o Paulo, Brazil. E-mail: dbhofling@uol.com.br Accepted 4 May 2010 Published online 15 July 2010 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/lsm.20941 ß 2010 Wiley-Liss, Inc.