Effect of long-term l-thyroxine treatment on bone mineral density in young adults with congenital hypothyroidism

Abstract

Objective: To evaluate whether long-term L-thyroxine therapy in young adults with congenital hypothyroidism may affect bone mineral density (BMD). Design: Thirty-seven subjects with congenital hypothyroidism, detected by neonatal screening and longitudinally followed from the time of diagnosis and treatment (26^4 days) up to the age of 17.8^1.0 years, were studied. Methods: Spinal (L2-L4) BMD, measured by dual-energy X-ray densitometry, and bone quality, measured as amplitude-dependent speed of sound (Ad-SoS) by quantitative ultrasound, were evaluated. Results: Z-score mean values (^S.D.) of BMD (20.3^0.7) and Ad-SoS (20.7^1. 1) were slightly below the average but within the normal range. Ad-SoS resulted in a z-score below 21 in 38% of patients as compared with BMD which resulted in a z-score below 2 1 in only 13.5% of subject. No significant differences were observed between males (BMD, 20.3^0.7; Ad-SoS, 20.9^1.0) and females (BMD, 2 0.3^0.7; Ad-SoS, 2 0.5^1.2) or when dividing patients on the basis of aetiological defects; ectopic gland (BMD, 20.3^0.6; Ad-SoS, 2 0.8^0.9), athyreosis (BMD, 20.3^0.9; Ad-SoS, 2 0.8^1.0) and eutopic gland (BMD, 2 0.3^0.8; Ad-SoS, 20.4^1.3). No significant relationships were observed between BMD or Ad-SoS z-score and hormonal status or L-thyroxine dosages at the time of the study or during the pubertal period. Conclusions: The careful monitoring of serum thyroid-stimulating hormone and adjustment of L-thyroxine dosage avoided the significant deleterious effects of prolonged L-thyroxine replacement therapy on bone tissue in adolescents and young adults with congenital hypothyroidism treated from the neonatal period.European Journal of Endocrinology 151 689-694

ENDOCRINOLOGY AND ADOLESCENCE: Congenital hypothyroidism: a clinical update of long-term outcome in young adults

“…Patients overtreated with thyroxine display higher levels of bone resorption than of bone formation, leading to progressive bone loss. Bone mineral density and body composition in children and young adults with CH seem to be within the normal range (41,98,99,100). However, more long-term data are required for patients treated with the doses in current use.…”

Thyroid hormone independent associations between serum TSH levels and indicators of bone turnover in cured patients with differentiated thyroid carcinoma.

“…Thyroid hormone indirectly promotes osteoclast formation and activation by inducing the expression of cytokines, prostaglandins, and the receptor activator of nuclear factor NFkB ligand (RANKL) (8)(9)(10). Apart from overt hyperthyroidism, subclinical hyperthyroidism also appears to be associated with decreased bone mineral density (BMD) as reviewed by Heemstra et al (3,11,12). …”

Densidade mineral óssea de crianças e adolescentes com hipotireoidismo congênito

“…Entretanto, até o momento, poucos autores estudaram a massa óssea em crianças e adolescentes com HC, e os estudos existentes mostram DMO normal e semelhante à dos controles na coluna lombar (12)(13)(14)(15)(16), fê-mur (12,14,15) e falanges proximais (16). Estes autores concluíram que o tratamento prolongado e cuidadosamente monitorizado com altas doses de l-T 4 não causariam a diminuição da massa óssea na infância e, se houvesse um efeito deletério sobre o esqueleto, o crescimento longitudinal teria reparado o dano com sucesso até a idade dos pacientes destes estudos (12)(13)(14)(15)(16). Por sua vez, Demeester-Mirkine e cols.…”