[Does L-thyroxine administration in a dose to suppress TSH secretion induce metabolic bone disturbance in patients...

We investigated whether L-thyroxine for TSH suppression may induce metabolic bone disturbance, especially in trabecular bone. Subjects were 75 premenopausal women (mean age: 37.7) who underwent surgery at Ito Hospital or Yokohama City University Hospital from 1972 to 1988 for differentiated thyroid carcinoma. All of them received L-thyroxine for the purpose of TSH suppression. According to the duration of the drug therapy after surgery, they were divided into 3 groups: Group I patients were treated for more than 10 years after surgery (17 cases), Group II from 5 to 10 years (28 cases), and Group III less than 5 years (30 cases). The control group was consisted of 15 premenopausal women (mean age: 37.0). There was no significant difference in age among these 4 groups. Quantitative CT was used for evaluation of trabecular bone mineral content. Mean bone mineral contents determined in Group I, Group III, Group II and control group patients were 204.7, 213.1, 207.6, 222.6 mg/cm3, respectively. There was no significant difference among them. It is concluded that L-thyroxine can be administered safely without metabolic disturbance in trabecular bone.