Effect of Suppressive Levothyroxine Therapy on Bone Mineral Density in Young Patients with Differentiated Thyroid Carcinoma

• Published in: Metabolites 2022-09, Vol.12 (9), p.842
• Main Authors: Zanella, André Borsatto, Marmitt, Laura, Fighera, Tayane Muniz, Scheffel, Rafael Selbach, Spritzer, Poli Mara, Dora, José Miguel, Maia, Ana Luiza
• Format: Article
• Language: English
• Subjects: Body mass index; Bone density; Bone mass; Bone mineral density; Bones; Cancer; Carcinoma; Care and treatment; Decision making; Density; differentiated thyroid carcinoma; Drug dosages; Dual energy X-ray absorptiometry; Femur; Fractures; Hormones; Osteoporosis; pediatric patients; Pediatric research; Pediatrics; Physiological aspects; Spine (lumbar); suppressive levothyroxine; Thyroid cancer; Thyroid carcinoma; Thyroid diseases; Thyroid-stimulating hormone; Thyroidectomy; Thyroxine; Young adults
• ISSN: 2218-1989; 2218-1989
• DOI: 10.3390/metabo12090842

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.