Chronic
autoimmune thyroiditis (CAT) is the most common cause of acquired
hypothyroidism, which requires lifelong
levothyroxine replacement
therapy. Currently, no effective
therapy is available for CAT. Thus, the objective of this study was to evaluate the efficacy of
low-level laser therapy (
LLLT) in patients with CAT-induced
hypothyroidism by testing thyroid function,
thyroid peroxidase antibodies (TPOAb),
thyroglobulin antibodies (TgAb), and ultrasonographic echogenicity. A randomized, placebo-controlled trial with a 9-month follow-up was conducted from 2006 to 2009. Forty-three patients with a history of
levothyroxine therapy for CAT-induced
hypothyroidism were randomly assigned to receive either 10 sessions of
LLLT (830 nm, output power of 50 mW, and fluence of 707 J/cm(2); L group, n=23) or 10 sessions of a placebo treatment (P group, n=20). The
levothyroxine was suspended 30 days after the
LLLT or placebo procedures. Thyroid function was estimated by the
levothyroxine dose required to achieve normal concentrations of T3, T4, free-T4 (fT4), and
thyrotropin after 9 months of postlevothyroxine withdrawal. Autoimmunity was assessed by measuring the TPOAb and TgAb levels. A quantitative computerized echogenicity analysis was performed pre- and 30 days postintervention. The results showed a significant difference in the mean
levothyroxine dose required to treat the
hypothyroidism between the L group (38.59 ± 20.22 μg/day) and the P group (106.88 ± 22.90 μg/day, P<0.001). Lower TPOAb (P=0.043) and greater echogenicity (P<0.001) were also noted in the L group. No TgAb difference was observed. These findings suggest that
LLLT was effective at improving thyroid function, promoting reduced TPOAb-mediated autoimmunity and increasing thyroid echogenicity in patients with CAT
hypothyroidism.