Effect of Suppressive Levothyroxine Therapy on Bone Mineral Density in Young Patients with Differentiated Thyroid Carcinoma
André Borsatto Zanella,
Laura Marmitt,
Tayane Muniz Fighera,
Rafael Selbach Scheffel,
Poli Mara Spritzer,
José Miguel Dora,
Ana Luiza Maia
Affiliations
André Borsatto Zanella
Thyroid Unit, Endocrinology Division, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre 90410-000, Brazil
Laura Marmitt
Thyroid Unit, Endocrinology Division, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre 90410-000, Brazil
Tayane Muniz Fighera
Gynecological Endocrinology Unit, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre 90410-000, Brazil
Rafael Selbach Scheffel
Thyroid Unit, Endocrinology Division, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre 90410-000, Brazil
Poli Mara Spritzer
Gynecological Endocrinology Unit, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Porto Alegre 90410-000, Brazil
José Miguel Dora
Thyroid Unit, Endocrinology Division, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre 90410-000, Brazil
Ana Luiza Maia
Thyroid Unit, Endocrinology Division, Hospital de Clínicas de Porto Alegre, Medical School, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre 90410-000, Brazil
Suppressive levothyroxine therapy (sT4) is a cornerstone in the management of differentiated thyroid cancer (DTC). Long-term sT4 may affect bone mineral density (BMD). We evaluated the effect of sT4 on the bone mass of young DTC patients. In this cross-sectional study, BMD was evaluated via dual-energy X-ray absorptiometry in DTC patients younger than 25 years at diagnosis and undergoing sT4 for ≥1 year. The two control groups comprised patients matched for sex, age, and body-mass-index who were thyroidectomized for indications other than DTC and undergoing L-T4-replacement therapy, and healthy individuals with no prior known thyroid disease. Ninety-three participants were included (thirty-one in each group). There were no differences in the mean age, female sex (77.4% in all groups), or BMI between the sT4 group and each control group. The median TSH level was lower (0.4 [0.04–6.5] vs. 2.7 [0.8–8.5] mIU/mL, p = 0.01) and the mean L-T4 mcg/Kg levels were higher (2.4 ± 0.6 vs. 1.6 ± 0.3, p = 0.01) in the sT4 group compared to the L-T4-replacement therapy group. Lumbar spine, femoral neck, and total femur BMD were all similar among the groups. sT4 does not impact BMD in young DTC patients after a median time of suppression of 8 years. These findings may help in the decision-making and risk/benefit evaluation of sT4 for this population.
