Use of disphosphonates in the treatment of osteoporosis in thyroidectomized patients on levothyroxin replacement therapy

Bone mineral density at medio distal (MD-BMD) and ultra distal (UD-BMD) sites of non dominant radius were studied, using a DEXA Mineralometer (TURBOSCAN-NIM) on a series of 20 patients, over 60 years old, all thyroidectomized for thyroid carcinoma and treated with levothyroxin replacement therapy. T3 and T4 (RIA method), TSH (IRMA method) and two cardiac parameters as TPER (time peak ejection rate) and TPFR (time peak filling rate) by angiocardioscintigraphy were also determined. Results showed that 19 patients considering MD-BMD values and ten considering UD-BMD values were at risk of fractures. Circulating T3 levels were within normal range in 17 patients, elevated in two cases and reduced in one case. Circulating T4 levels were within normal range in 15 patients, increased in four cases and reduced in one case. Circulating TSH levels were within normal range in 17 patients, reduced in two cases and elevated in one case. TPER were reduced in 18 patients and normal in two cases. TPFR were reduced in six patients and normal in fourteen cases. The authors administered alendronate (10 mg/day) which seems to prevent bone loss, especially at the level of the trabecular bone. Bone loss reverted at 6 and 12 months, confirming that disphosphonates slow down this phenomenon in a situation of increased bone turnover (e.g. patients on long-term L-T4 therapy).