Longitudinal study of bone loss after thyroidectomy and suppressive thyroxine therapy in premenopausal women

Abstract

Passeri M. Longitudinal study of bone loss after thyroidectomy and suppressive thyroxine therapy in premenopausal women. Acta Endocrinol 1992:126:238-42. The effects of suppressive doses of L-thyroxine on the appendicular and axial bone mineral content were followed for 12\p=n-\36 months after total or subtotal thyroidectomy in 15 premenopausal women. Compared to age-matched controls, these patients had a more marked bone loss of the spinal bone mineral content (2.6 \m=+-\1.9% vs 0.2 \m=+-\ 1.2% per year). The changes in radial cortical bone density were not significantly different from the control group. We conclude that when a suppressive therapy with L-thyroxine is necessary the rate of bone loss should be monitored at regular intervals.Suppressive doses of L-thyroxine. a common form of therapy after thyroidectomy for different thyroid dis¬ eases, prevent further growth of abnormal tissue. Patients taking suppressive doses of L-thyroxine fre¬ quently have elevated serum thyroxine and free thyrox¬ ine concentrations, but serum triiodothyronine levels are within the normal range ( 1 ). These patients do not usually show biological or clinical signs of hyperthyroidism, but controversy exists as to whether such patients might have adverse tissue effects (2, 3). Thyroid hor¬ mones have important effects on bone metabolism and hyperthyroidism alters the bone remodelling activity and increases mainly cortical bone porosity, even if trabecular volume and cortical width may also be reduced (4). Cross-sectional studies have shown a reduction in bone density after prolonged suppression of the pituitary-thyroid axis with L-thyroxine (5-7) and marked bone mineral changes have been observed also under replacement therapy in hypothyroidism (8,9).The bone effects of thyroid hormone therapy could be particularly important in thyroidectomized patients in whom a decrement of calcitonin secretion, a potentially protective factor for bone (10), occurs.The aim of this longitudinal study was to assess the effects of suppressive doses of L-thyroxine on the appen¬ dicular and axial bone mineral content in premenopau¬ sal thyroidectomized women. Materials and methodsThe subjects for the study were chosen from all the premenopausal women consecutively admitted during the course of one year for thyroidectomy and were candidates for suppressive therapy. Criteria for exclusion were the presence of other medical disorders, the use of drugs known to interfere with bone and mineral metab¬ olism or previous treatment with thyroid hormones.Fourteen premenopausal women (age: 43 ±6.8 years) undergoing thyroidectomy for goiter (N = 6) and carcinoma (N = 8) were recruited. All the patients were euthyroid at the time of the study. Each subject gave written informed consent to the study.Ten patients underwent near-total thyroidectomy and four subtotal thyroidectomy. All were normally men¬ struating before and throughout the study. After surgery the women began a suppressive therapy with L-thyrox¬ ine. The initial dose was 150¿ug/day (3 ¿tg-kg^-day-1...

Bone Changes in Pre- and Postmenopausal Women with Thyroid Cancer on Levothyroxine Therapy: Evolution of Axial and Appendicular Bone Mass

“…In these studies significant reductions in the lumbar spine bone mass were found. Pioli et al [14] found no change in appendicular bone mass and a linear decrease at the lumbar spine in previously euthyroid patients on suppressive therapy compared with a control group using SPA and DPA measures. The change at the femoral neck was not assessed.…”

“…Again, differences in the number of patients enrolled, previous history and previous thyroid status, concomitant medication, degree of suppression, selection of the control group or bone mass measurement techniques may explain the differences with the few longitudinal studies available [13][14][15]. In these studies significant reductions in the lumbar spine bone mass were found.…”

“…Confounding variables such as parathyroid and menopausal status, and also prior history of hyperthyroidism, may be responsible for such differences. Recent prospective studies have shown an accelerated bone loss in these patients, at spinal and/ or femoral neck and radius sites [13][14][15]. Nevertheless, previous cross-sectional studies report that cortical bone is affected more than trabecular bone (for review see [7]) and that postmenopausal women are affected more than premenopausal women, as shown in a recent metaanalysis [16].…”

Is there an ectopic secretion of monomeric calcitonin in the human being?

“…There are a number of publications that did not report any changes of the basal CT levels after thyroidectomy [6,7,10,13,15,21]. The diverging results may have been caused by the different therapeutic treatment of the examined patients.…”

“…Consequently, these tissues are potential sources of ectopic CT secretion. It is known from recent publications that ectopic secretion of CT (polymeric or monomeric CT as well as CT precursors) is detectable by less specific assays [10,15]. In recent years, the specificity of two-site immunoassays could be increased by a combination of specific antibodies against CT.…”