Muscle force and bone mineral density after parathyroidectomy and subcutaneous autotransplantation for secondary hyperparathyroidism.

Abstract

The object of this study was to determine the muscle force and bone mineral density (BMD) of patients with secondary hyperparathyroidism before and 3 months after operation. Thirty-nine patients with secondary hyperparathyroidism and regular dialysis were operated. Their ages were 47 +/- 12 (mean +/- SD) years and duration of dialysis was 70.5 +/- 35.8 months. The clinical symptoms included bone pain in 23 patients (59%), skin itching in 21 (53.8%), general weakness in 13 (33.3%), conscious disturbance in 2, chest tightness in 1, and failure to thrive in 1. Total parathyroidectomy and autotransplantation of 60 mg of parathyroid gland into subcutaneous tissue was done routinely. BMD was measured in the lumbar spine (L2-L4) and left proximal femur, expressed as grams per square centimeter and as fracture risk. The extension force of the quadriceps muscle was measured at 60 degrees of right knee flexion, expressed as newtons (N) in a peak force and an average force. Three months after operation the BMD of the study group increased (in g/cm2) from 1.063 +/- 0.181 to 1.148 +/- 0.149 (p < 0.001) in L2-4 (n = 25), from 0.792 +/- 0.14 to 0.875 +/- 0.161 (p < 0.001), in femoral neck (n = 25), from 0.672 +/- 0.171 to 0.754 +/- 0.21 (p < 0. 001) in Ward's triangle (n = 25), and from 0.69 +/- 0.149 to 0.738 +/- 0.143 (p < 0.001) in trochanter (n = 25). Fracture risk also was reduced significantly 3 months after operation at L2-4 (p = 0.003), femoral neck (p = 0.001), Ward's triangle (p= 0.003), and trochanter (p = 0.005). Muscle force (in newtons) increased from 264.8 +/- 110. 5 to 326 +/- 110.9 (p = 0.023) in peak force (n = 18) and from 195.3 +/- 90.4 to 258 +/- 99 (p = 0.012) in average force (n = 18). The patients with general weakness had improved muscle force more prominently than those without general weakness. In addition to skin itching, bone pain, and soft tissue calcification, general weakness that causes disability is an indication for surgery in secondary hyperparathyroidism. After parathyroidectomy and autotransplantation, the muscle force tends to increase, especially in those with general weakness. An increment of BMD and reduction of fracture risk are also found after surgery.