Attenuation of postmenopausal bone loss in patients with transient hypoparathyroidism after total thyroidectomy

Increased bone mineral density (BMD) has been reported in patients with postsurgical permanent hypoparathyroidism. Hypoparathyroidism may attenuate the high-turnover bone loss in postmenopausal women. We reported previously that patients who had transient hypoparathyroidism postoperatively were at subclinical hypoparathyroid (hP) status even 5 years after surgery. We hypothesized that patients with transient hypoparathyroidism (ThP) may have altered BMD.

A total of 140 women who underwent total thyroidectomy had BMD measurements of the lumbar spine, femoral neck, and radius 3 years after surgery. At surgery, 99 patients were ≥50 years and 41 were <50 years. They were divided into three groups according to their postoperative parathyroid function: There were 80 patients in the no hP (NhP) group, 54 in the ThP group, and 6 in the permanent hP (PhP) group.

Among the 99 patients aged ≥50 years, 36 ThP patients had median Z scores of the BMD in all three areas (lumbar spine, femoral neck, radius) that were significantly higher (by 1.083, 0.533, and 1.047, respectively) than those in the 60 NhP patients aged ≥50 years. The BMDs in the three PhP patients ≥50 years were higher than those in the NhP and ThP patients, but the difference did not reach significance except for in the femoral neck. Multivariate logistic regression analyses showed that Z scores > 0 were significantly associated only with the presence of ThP postoperatively. In the patients <50 years, the BMD values were not significantly different among the three groups except at the radius in PhP patients, which was significantly lower than those of the other patients.

We found that ThP was associated with increased BMD in postmenopausal women. This may be due to attenuation of the high-turnover bone loss in postmenopausal women.