Effect of long-term L-thyroxine treatment on bone mineral density in young adults with congenital hypothyroidism.
OBJECTIVE
To evaluate whether long-term L-thyroxine therapy in young adults with congenital hypothyroidism may affect bone mineral density (BMD).


METHODS
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 (-0.3+/-0.7) and Ad-SoS (-0.7+/-1. 1) were slightly below the average but within the normal range. Ad-SoS resulted in a z-score below -1 in 38% of patients as compared with BMD which resulted in a z-score below -1 in only 13.5% of subject. No significant differences were observed between males (BMD, -0.3+/-0.7; Ad-SoS, -0.9+/-1.0) and females (BMD, -0.3+/-0.7; Ad-SoS, -0.5+/-1.2) or when dividing patients on the basis of aetiological defects; ectopic gland (BMD, -0.3+/-0.6; Ad-SoS, -0.8+/-0.9), athyreosis (BMD, -0.3+/-0.9; Ad-SoS, -0.8+/-1.0) and eutopic gland (BMD, -0.3+/-0.8; Ad-SoS, -0.4+/-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.
Salerno
Mariacarolina
M
Department of Pediatrics, University Federico II, Naples, Italy.
Lettiero
Teresa
T
Esposito-del Puente
Antonella
A
Esposito
Valentina
V
Capalbo
Donatella
D
Carpinelli
Assunta
A
Padula
Stefania
S
del Puente
Antonio
A
D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density / Q000187:drug effects*; D002136:Calcium, Dietary; D003409:Congenital Hypothyroidism; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000473:pathology*; D008297:Male; D011628:Puberty, Delayed / Q000150:complications / Q000000981:diagnostic imaging; D012727:Sex Characteristics; D013131:Spine / Q000000981:diagnostic imaging; D013974:Thyroxine / Q000009:adverse effects* / Q000627:therapeutic use; D014463:Ultrasonography
D002136:Calcium, Dietary; D013974:Thyroxine