The effects of recombinant human TSH on bone turnover in patients after thyroidectomy.

Thyrotropin receptors are expressed in several extrathyroidal tissues including bone. We investigated whether the increase of thyroid-stimulating hormone (TSH) levels, under stable thyroid hormone levels, affects the bone markers. Thirty-two postmenopausal women, with papillary thyroid carcinoma, previously treated with near-total thyroidectomy and I131 remnant ablation underwent routine evaluation for residual disease by using injections of recombinant human TSH (rhTSH) without withdrawal from thyroxine therapy. Changes in TSH levels and various serum and urine markers of bone metabolism were followed before and 1, 2, 5, and 7 days after the rhTSH injections. A transient, significant decrease in serum calcium and urinary excretion of C- and N-terminal telopeptides of type I collagen was observed after the injections of rhTSH. Serum parathyroid hormone (PTH) started to rise along with TSH, but a significant increase of PTH was only reached on Day 5 when the TSH concentration had fallen more than 80% of the peak value. Bone alkaline phosphatase and osteocalcin did not show any significant change over time. There was no significant correlation between TSH concentration and the various parameters we measured. The study provides evidence that rhTSH produces a transient inhibition of bone resorption, as well as an attenuation of osteoblast response in spite of the PTH activation. Additional studies are needed to resolve the mechanisms by which TSH alters the response of the bone cells.

L-thyroxine therapy attenuates the decline in serum triiodothyronine in nonthyroidal illness induced by hysterectomy.

It is controversial whether the administration of thyroid hormone to patients with nonthyroidal illness has any beneficial effect. Two groups of patients undergoing abdominal hysterectomy under the same general anesthesia were studied. Group A consisted of 15 women taking chronically l-thyroxine therapy (1.8 mug/kg daily), and group B (control) consisted of 16 apparently healthy euthyroid women taking placebo. Thyroid hormones, cortisol, and interleukin (IL)-6 were measured 1 day before and 1, 2, 3, and 6 days after surgery. Total triiodothyronine (TT(3)) decreased to a significantly greater degree (P <.05) and for a longer period of time in group B than in group A. The significant increase of reverse T(3) (rT(3)) noted early in group B failed to reach the baseline levels until the end of the study, whereas in group A, rT(3) returned to the preoperative values by day 2. Both groups had similar free thyroxine (FT(4)) at baseline. FT(4) increased significantly at day 1 and remained significantly elevated throughout the postoperative period in group B only. Serum TT(4), thyroid-stimulating hormone (TSH), and cortisol did not change significantly in either group. In all patients, IL-6 increased significantly to a peak value at day 1, showing a slow decrease thereafter. A stronger negative correlation was found between T(3) and IL-6 in group B than in group A (r = -.66, P <.0001 v r = -.38, P <.001, respectively) and a strong positive correlation was observed between rT(3) and IL-6 in group B only (r =.57, P <.001). The long-term treatment with T(4) seems to attenuate the decrease of serum T(3), which occurs during the development of nonthyroidal illness postoperatively. The elevation of IL-6 accounted for a greater proportion of the variations of the T(3) and rT(3) in the control group B than in the T(4)-treated group A.